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Takarkori rock shelter (SW Libya): an archive of Holocene climate and
environmental changes in the central Sahara
Mauro Cremaschi
a
, Andrea Zerboni
a
,
*
, Anna Maria Mercuri
b
, Linda Olmi
b
,
Stefano Biagetti
c
,
d
,
1
, Savino di Lernia
e
,
f
a
Dipartimento di Scienze della Terra “A. Desio”, Universit
a degli Studi di Milano, Via L. Mangiagalli 34, I-20133 Milano, Italy
b
Laboratorio di Palinologia e Paleobotanica, Dipartimento di Scienze della Vita, Universit
a di Modena e Reggio Emilia eViale Caduti in Guerra 127,
I-41121 Modena, Italy
c
The Italian Society for Ethnoarchaeology, Via dei Duchi di Castro 1, I-00135 Roma, Italy
d
Institute for Applied Archaeology and Sustainability, Via San Quintino 47, I-00185 Roma, Italy
e
Dipartimento di Scienze dell'Antichit
a, Sapienza Universit
a di Roma, Via dei Volsci 122, I-00185 Roma, Italy
f
School of Geography, Archaeology and Environmental Studies, University of the Witwatersrand, Private Bag 3, Johannesburg 2050, South Africa
article info
Article history:
Received 26 December 2013
Received in revised form
17 Ma y 20 14
Accepted 3 July 2014
Available online
Keywords:
Rock shelter site
Site formation processes
Climate changes
EarlyeMiddle Holocene
Micromorphology
Palynology
Hunteregatherers
Pastoralists
Tadrart Acacus
Sahara
abstract
Rock shelters in the central Saharan massifs preserve anthropogenic stratigraphic sequences that
represent both a precious archive for the prehistory of the region and a powerful proxy data for Holocene
palaeoenvironments. The geoarchaeological (micromorphology) and archaeobotanical (pollen analysis)
approaches were integrated to investigate the anthropogenic sedimentary sequence preserved within
the Takarkori rock shelter, a Holocene archaeological site located in the Libyan central Sahara (southern
Tadrart Acacus massif). The site was occupied throughout the Early and Middle Holocene (African Humid
Period) by groups of hunteregatherers before and by pastoral communities later. The investigation on
the inner part of the sequence allows to recognize the anthropogenic contribution to sedimentation
process, and to reconstruct the major changes in the Holocene climate. At the bottom of the stratigraphic
sequence, evidence for the earliest frequentation of the site by hunters and gatherers has been recog-
nized; it is dated to c. 10,170 cal yr BP and is characterized by high availability of water, freshwater
habitats and sparsely wooded savannah vegetation. A second Early Holocene occupation ended at c.
8180 cal yr BP; this phase is marked by increased aridity: sediments progressively richer in organics,
testifying to a more intense occupation of the site, and pollen spectra indicating a decrease of grassland
and the spreading of cattails, which followed a general lowering of lake level or widening of shallow-
water marginal habitats near the site. After this period, a new occupational phase is dated between c.
8180 and 5610 cal yr BP; this period saw the beginning of the frequentation of pastoral groups and is
marked by an important change in the forming processes of the sequence. Sediments and pollen spectra
confirm a new increase in water availability, which led to a change in the landscape surrounding the
Takarkori rock shelter with the spreading of water bodies. The upper part of the sequence, dating
between c. 5700 and 4650 cal yr BP records a significant environmental instability towards dryer climatic
conditions, consistent with the end of the African Humid Period. Though some freshwater habitats were
still present, increasing aridity pushed the expansion of the dry savannah. The final transition to arid
conditions is indicated by the preservation of ovicaprines dung layers at the top of the sequence together
with sandstone blocks collapsed from the shelter's vault. On the contrary, the outer part of the sequence
preserves a significantly different palaeoenvironmental signal; in fact, the surface was exposed to rainfall
and a complex pedogenetic evolution of the sequence occurred, encompassing the formation of an
argillic laminar horizon at the topsoil, the evolution of a desert pavement, and the deposition of Mn-rich
rock varnish on stones. These processes are an effect of the general environmental instability that
occurred in the central Sahara since the Middle Holocene transition. Finally, the local palaeoclimatic
significance of the sequence fits well with Holocene regional and continental environmental changes
*Corresponding author. Tel.: þ39 02 50315292; fax: þ39 02 50315494.
E-mail address: andrea.zerboni@unimi.it (A. Zerboni).
1
www.ethnoarchaeology.org.
Contents lists available at ScienceDirect
Quaternary Science Reviews
journal homepage: www.elsevier.com/locate/quascirev
http://dx.doi.org/10.1016/j.quascirev.2014.07.004
0277-3791/©2014 Elsevier Ltd. All rights reserved.
Quaternary Science Reviews 101 (2014) 36e60
recorded by many palaeohydrological records from North Africa. This highlights the potential of geo-
archaeological and archaeobotanical investigations in interpreting the palaeoenvironmental significance
of anthropogenic cave sediments in arid lands.
©2014 Elsevier Ltd. All rights reserved.
1. Introduction
Key to understand Holocene palaeoclimatic and palae-
oenvironmental oscillations is disentangling and isolating climatic
and human impacts on the landscape and environment and dis-
tinguishing the relative contribution of each (e.g., Cullen et al.,
2000; Messerli et al., 2000; Bolle, 2003; Ruddiman, 2003, 2007;
Butzer, 2005; Coombes and Barber, 2005; Kuper and Kr€
opelin,
2006; Roberts et al., 2008;Zanchetta et al., 2013). Within this
framework, the geoarchaeological and archaeobotanical study of
archaeological sequences, defined as human-disturbed deposits, is
of crucial importance to understand the human overprint on
climate-triggered palaeoenvironmental changes and geomorphic
processes (e.g., Anderson et al., 2007; Cremaschi and Zerboni, 2011;
Mercuri et al., 2011; Roberts et al., 2011b). However, to infer
palaeoenvironmental and palaeoclimatic information from human-
disturbed deposits, a multidisciplinary approach integrating the
study of sediments, biological remains and material culture is
required.
Cave sediments formed during the human occupation of rock
shelters (e.g., Goldberg and Macphail, 2006; Weiner, 2010 and
references cited therein) are an example of anthropogenic deposits
with great potential for palaeoclimatic studies. Among such sam-
ples, the Holocene infillings of the rock shelters of the Tadrart
Acacus Massif (Central Sahara, South-West Libya) play an important
role in palaeoenvironmental reconstructions, as they resulted from
peculiar depositional and post-depositional processes controlled by
both natural and anthropic factors (e.g., Cremaschi, 1998;
Cremaschi and di Lernia, 1999a; Mercuri, 2008a; Cremaschi and
Zerboni, 2011; Biagetti and di Lernia, 2013). These deposits date
back to a pivotal period for human development as they include the
transition from hunteregatherer subsistence to food production
(e.g., Barich, 1987; Cremaschi and di Lernia, 1998; di Lernia, 1999,
2001, 2002). This event occurred in the Early Holocene, during
the African Humid Period (AHP), c. 11,000e600 0 calyr BP, when the
Sahara, different from its present aridity, was fed by monsoon rain
and covered by patches of savannah (e.g., L
ezine, 1989; Gasse and
Van Campo, 1994; Gasse, 2000; Hoelzmann et al., 2004;Kuper
and Kr€
opelin, 2006;L
ezine et al., 2011).
Numerous caves and rock shelters dot the walls flanking the
fossil drainage network that dissect the Tadrart Acacus massif. They
formed under a Tertiary warm and humid (tropical) climate thanks
to solutional processes (Cremaschi, 1998; Zerboni, 2011). Also, most
of them are renowned for their rock art galleries (e.g., Mori,1965; di
Lernia and Zampetti, 2008), placed on the UNESCO World Heritage
List in 1985. Since the 1960s, archaeological excavation carried out
at several cave sites in Libya and Algeria (for instance, at Ti-n-
Hanakaten, Ti-n-Torha, wadi Athal, Uan Telocat, Uan Tabu, Uan
Afuda, Uan Muhuggiah, Fozzigiaren) has illustrated that the infill-
ings of rock shelters preserve sequences of utmost archaeological
and biological relevance, most of which include the Upper Pleis-
tocene and the Early and Middle Holocene (Pasa and Pasa Durante,
1962; Barich and Mori, 1970; Aumassip and Delibrias, 1982; Hachi,
1983; Aumassip, 1984; Barich, 1987; Schulz, 1987; Wasylikowa,
1992; Cremaschi, 1998; Mercuri et al., 1998; Cremaschi and di
Lernia, 1998, 1999a; Cremaschi and Trombino, 1999; di Lernia,
1999; Garcea, 2001; Mercuri, 2008b; Linseele et al., 2010;
Cremaschi and Zerboni, 2011; Biagetti and di Lernia, 2013). The
peculiarity of the sequences is the surprising preservation of
organic matter, especially for the Holocene contexts; this has made
these deposits high-quality archives in which archaeological evi-
dence can be studied in its environmental context. Specifically, they
offer the possibility to understand (if and) how human groups
coped locally with environmental variations and changes in natural
resource availability over the course of the Holocene.
In many cases, the human overprint on sediments, in combi-
nation with local processes (e.g., human-driven processes and
micro-environmental factors), has increased the complexity of
stratigraphic records. This makes it difficult to interpret such re-
cords from the perspective of palaeoenvironmental reconstruction.
Taking this into consideration, the sequence of the Takarkori rock
shelter (Fig. 1) was selected to perform an interdisciplinary study of
the natural and anthropic depositional and post-depositional pro-
cesses affecting a central Saharan cave filling.
Due to a thick and composite stratigraphic sequence that spans
several millennia and a rich archaeological context, the Takarkori
site might be considered representative of the central Saharan
massifs, being one of the few locales in the central Sahara preser-
ving the transition from hunting and gathering to food production.
Some of the archaeological and bio-anthropological aspects have
been already published (Biagetti et al., 2004, 2009; Tafuri et al.,
2006; Biagetti and di Lernia, 2007, 2013; Olmi et al., 2011; di
Lernia et al., 2012; Dunne et al., 2012; Biagetti and di Lernia,
2013; Cherkinsky and di Lernia, 2013; di Lernia and Tafuri, 2013),
confirming that the site represents an outstanding laboratory for
multidisciplinary archaeological research.
This paper focuses on processes that contributed to the forma-
tion of the stratigraphic sequence, mostly on the basis of geo-
archaeological and palynological evidence. Data are interpreted
from a palaeoclimatic and palaeoenvironmental perspective. In
fact, besides human activities, global environmental factors and
local environmental (or micro-environmental) settings are inter-
preted as actors in the formation processes. Furthermore, data from
the site are compared with the regional and continental archives
for Holocene environmental modifications, demonstrating the high
sensitivity of Saharan cave sediments to global climate changes.
2. Palaeoclimate and past environments of the central Sahara
From the Early to the Middle Holocene, the central Sahara
enjoyed a period of high rainfall, as did the entire region (e.g.,
Cremaschi, 1998, 2002; Gasse, 2000; deMenocal et al., 2000;
Hoelzmann et al., 2004; Mayewski et al., 2004; Kuper and
Kr€
opelin, 2006; Wendorf et al., 2007; Arbuszewski et al., 2013).
Data from interdune lake deposits (Cremaschi, 1998; Zerboni, 2006;
Cremaschi and Zerboni, 2009; Zerboni and Cremaschi, 2012),
spring tufa (Cremaschi et al., 2010) and anthropogenic sequences
inside rock shelters (Cremaschi, 1998; Mercuri, 2008b; Cremaschi
and Zerboni, 2011) indicate that the renewal of water reservoirs
and the expansion of the savannah vegetation date to the beginning
of the Holocene. The recharge of the aquifers during the AHP was
driven by the extension of the summer monsoon from the Gulf of
Guinea and the migration of the ITCZ (Intertropical Convergence
Zone) to northern positions (Gasse, 2000; deMenocal et al., 2000),
M. Cremaschi et al. / Quaternary Science Reviews 101 (2014) 36e60 37
impacted by a maximum solar heating of the Earth. In the region, a
dramatic interruption of the AHP is dated to c. 8000 cal yr BP
(Cremaschi et al., 2010; Zerboni and Cremaschi, 2012), while its
termination, preserved in palaeohydrological records and pollen
spectra, occurred after the Middle Holocene transition (Cremaschi,
1998; Cremaschi et al., 2006; Mercuri, 2008b; Cremaschi and
Zerboni, 2009). At that time, water resources decreased and the
desert expanded up to its current limit. This led to the present
desert conditions following different ways as the varying physio-
graphic and biological features responded differently to aridifica-
tion (Cremaschi and Zerboni, 2009, 2011; Mercuri et al., 2011).
Pollen and plant macro-remains from the anthropogenic sedi-
ments of rock shelters give further information about the envi-
ronmental conditions during the Early and Middle Holocene and
the adaptive strategies of human groups living in the area. Per-
manent wet habitats (with Typha and aquatics such as Potamoge-
ton) and a fairly continuous grassland (abundant caryopses of
Brachiaria,Urochloa and other Paniceae) were featured in the plant
landscape during the earlier phases of human occupation, which
would have provided an abundance of natural resources to gath-
erers and foragers until c. 8600 cal yr BP (Mercuri, 2001 and ref-
erences therein; Mercuri, 2008b). Wet conditions permitted the
maintenance of moist environments and development of a Cyper-
aceaeePoaceae savannah cover until c. 6300 cal yr BP. The green
cover was suitable to sustain domestic animals of pastoralists and
withstand their browsing. However, the perennial vegetation of the
first phase gave way to semi-arid seasonal savannah in the second.
The decrease of freshwater habitats, increase of bushlands and the
addition of new species, floristic changes in grass cover and the
spread of desert vegetation were fairly gradual under increasing
seasonality. The psammophilous vegetation (e.g., pollen of Cornu-
laca monacantha and Moltkiopsis ciliata), indicating the spreading of
dunes and beginning of a hyperarid environment, expanded after c.
6300 cal yr BP (Mercuri, 2008a,b).
During the AHP, caves and rock shelters of the central Sahara
were frequented regularly (Mori,1965; Barich, 1987; Cremaschi and
di Lernia, 1998; di Lernia, 1999; Garcea, 2001). They were occupied
first by groups of Early Holocene hunteregatherers (between c.
11,100 and 8200 cal yr BP), and later by cattle and sheep/goat
herders (between c. 8000 and 4500 cal yr BP); during historical
times rock shelters were occasionally occupied by the Garamantes,
while in recent times they have been exploited by Tuareg.
3. The Takarkori rock shelter in its regional setting
The Takarkori rock shelter is located on the left bank of wadi
Takarkori (Fig. 1), which is the largest pass that separates the
Tadrart Acacus in Libya from the Algerian Tadrart (Desio, 1937; El-
Fig. 1. (A) Landsat satellite imagery showing the position of the Takarkori rock shelter in the southern Tadrart Acacus massif; the grey transect refers to the area of the Wadi
Takarkori Project, while the star indicates the position of the rock shelter. The insert (B) indicates the study site in its regional context and illustrates the extant position of the ITCZ
(dotted line) and main regional winds (arrows). (C) A detail of the Takarkori area (Google Earth™) encompassing the rock shelter and the depression formerly occupied by a lake
(indicated by the arrow).
M. Cremaschi et al. / Quaternary Science Reviews 101 (2014) 36e6038
ghali, 2005) and was identified during the geoarchaeological sur-
vey of the area in 1999 by one of the authors (MC). A detailed
geomorphological survey of the Takarkori area (in the field for the
Libyan territory, on the basis of remote sensing analyses for the
Algerian bank) elucidated the physiographic settings of the region.
The rock shelter is close to an endorheic basin (Figs. 1 and 2), fed by
a complex fluviatile system originating from the Algerian Tassili
and, on the basis of geoarchaeological evidence, active until the
onset of desert conditions after the Middle Holocene transition.
During the AHP the depression was occupied by a lake fed by
several influents that descended from the Algerian heights. The
shores of the lake (Fig. 2) are at present indicated by the occurrence
of a silty to sandy sediment rich in organic matter; they are quite
evident and are dotted by the vestiges of Holocene archaeological
sites (fireplaces, pits, grinding equipments, lithics and pottery),
which record the life of the lake up to the Middle Holocene.
The present climate of the region is hyperarid. The mean annual
temperature is approximately 30
C (at the Ghat weather station),
and the mean annual rainfall is between 0 and 20 mm, mostly
distributed in spring and summer (Walther and Lieth, 1960; El-
Tantawi, 2005). The surrounding vegetation is sparse and limited
to AcaciaePanicum communities (White, 1983; Schmidt, 2003;
Mercuri, 2008a).
The rock shelter is positioned on a structural terrace of the
Tadrart Acacus sandstone massif, approximately 100 m above the
wadi floor (Figs. 1 and 2). It opens westwards onto a large shelf
(ca 2200 m
2
) and, through the process of undersapping, developed
in the shape of alcove-type morphology (Fig. 3) at the interlayer of
the local sandstone (Young et al., 2009). Most of the archaeological
deposit has been eroded, as attested by artefacts' distribution on
the surface of a stone-dominated desert pavement surrounding the
site (Biagetti et al., 2004). However, the deposit survives
(ca 200 m
2
) in the most recessed part of the shelter (Figs. 3 and 4):
its preservation is also due to the presence of boulders that fell from
the vault as well as arranged stones, which constitute part of the
same filling. This part of the deposit was excavated under the di-
rection of one of us (SdL) between 2003 and 2006 (Biagetti and di
Lernia, 2013) in four sectors over 143 m
2
of investigated surface
(Fig. 4): (i) the Northern Sector (TK-NS), a 4 2 m trench; (ii) the
Main Sector (TK-MS), the largest area of excavation (117 m
2
), near
the rock wall and better protected by wind erosion (it includes a
stone cairn found empty); and (iii) the Western Sector (TK-WS), a
33 m trench located beyond the drip line of the rock shelter,
where the surface potsherds were present in the highest
concentration.
4. Material and methods
The strategies employed during the archaeological excavation of
the deposit and the main archaeological finds are described in
Fig. 2. Geomorphological map of the wadi Takarkori area illustrating the main geomorphological units and their age; the star indicates the position of the Takarkori rock shelter.
Key: 1) Palaeozoic sandstone bedrock; 2) slope deposits (Tertiary/Quaternary); 3) red dunes (Tertiary/Early Quaternary); 4) yellow dunes (Holocene); 5) fluvial gravel (Holocene); 6)
swamp deposit (Holocene); 7) shore deposit (Holocene); 8) recent alluvium (Late Holocene).
M. Cremaschi et al. / Quaternary Science Reviews 101 (2014) 36e60 39
Biagetti and di Lernia (2013 and references therein). This study
reports sedimentological, micromorphological and palynological
analyses carried out on samples collected from the TK-NS and along
a section opened in the TK-WS. The deposits found in the inner part
of the rock shelter (TK-NS), due to their position, suffered limited
wind erosion; on the other hand, sediments from TK-WS, which are
located outside the drip line, suffered more severe weathering.
Comparison of the results from the two deposit areas (TK-NS and
TK-WS) offers the opportunity to understand the depositional and
post-depositional processes acting in two different topographic
settings.
Besides archaeological excavation, the area surrounding the
rock shelter was surveyed to check the geomorphological context of
the range, which humans crossed to find natural resources (Biagetti
and di Lernia, 2013). The survey was mostly dedicated to the area at
the bottom of the wadi Takarkori, where satellite imagery evi-
denced the existence of an ancient lake (Figs. 1 and 2). Archaeo-
logical sites are very common along the shores of the lake, and this
is a further proof that a strict relationship existed between the area
of the lake and the rock shelter. From a palaeoecological point of
view, in the Holocene the flat area at the basis of the site, which also
included the swamp, was exploited for a long time and represented
a composite unit of the archaeological landscape, where the in-
habitants of Takarkori acted during their occupation of the rock
shelter.
4.1. Chronology of the stratigraphic sequence
The periodization of the Holocene human occupation of the rock
shelter is crucial for a comprehensive chronological assessment of
the strata formation and to interpret their palaeoenvironmental
significance. A first chronology of the stratigraphic sequence was
provided by archaeological finds (mostly pottery and lithics), clas-
sified according to the cultural phases of the Holocene Prehistory in
the Sahara as discussed in Cremaschi and di Lernia (1998) and di
Lernia (1999). The archaeological stratigraphy was also supported
by more than 40 conventional and AMS (Accelerator Mass Spec-
trometry) radiocarbon dates performed on organic matter-rich
sediment, charcoal, dried plant, human and faunal remains.
14
C
results are published in Dunne et al. (2012), di Lernia et al. (2012),
di Lernia and Tafuri (2013), Biagetti and di Lernia (2013) and
Cherkinsky and di Lernia (2013): the latter paper includes a full
discussion of calibration and statistical distribution of radiocarbon
dates from the Takarkori rock shelter and the time constraints of
archaeological horizons. Calibrated dates, expressed as cal yr BP,
were obtained using OxCal online version 4.1 (Bronk Ramsey,
2009); they are summarized in Table 3. According to the results
discussed by Cherkinsky and di Lernia (2013), the Takarkori rock
shelter was occupied during several phases, which overlap with the
main cultural horizons identified for the Holocene exploitation of
the Tadrart Acacus massif (Cremaschi and di Lernia, 1998). The
cultural horizons are: Late Acacus (LA) from 10,170 to
8180 cal yr BP; Early Pastoral Neolithic (EP), 8000 to 6890 cal yr BP;
Middle Pastoral Neolithic (MP), 7160 to 5610 cal yr BP; and Late
Pastoral Neolithic (LP), 5700 to 4650 cal yr BP.
On the basis of archaeological data (Biagetti and di Lernia,
2013), it is possible to distinguish between an exploitation of the
rock shelter by groups of hunteregatherers in the early Holocene
(LA phase) and a longer Pastoral Neolithic occupation (EP, MP, LP
phases) characterized by cattle and ovicaprine herders. Stone
structures, huts, and fireplaces together with large quantities of
grinding stones and potsherds suggest a prolonged, semi-
residential use of the area, which started with the occupation of
the LA foragers from c. 10,170 to 8180 cal yr BP (Biagetti et al.,
2004, 2009; Biagetti and di Lernia, 2013). The EP occupation is
represented by some fireplaces and strips of organic layers
together with several human graves (Tafuri et al., 2006; di Lernia
and Tafuri, 2013). These finds are the remains of thicker deposits
Fig. 3. (A) General view of the Takarkori rock shelter; an archaeologist for scale (arrow). (B) Panoramic view of the landscape surrounding the site as seen from the outer part of the
rock shelter; note in the lower part of (B) the position of the ancient swamp and in the background the Algerian Tassili.
Fig. 4. Simplified representation of the areas investigated within the Takarkori rock
shelter. Key: 1) limit of the rock shelter; 2) drip line; 3) margin of the terrace; 4)
position of the stratigraphic sections described in the text and in Tabs. 1 and 2, and
reported in Figs. 5 and 6 (AA0: TK-NS; BB0: TK-WS).
M. Cremaschi et al. / Quaternary Science Reviews 101 (2014) 36e6040
possibly removed by erosion and indicate the use of the site by
cattle herders from c. 8180 to 6890 cal yr BP. The MP occupation of
the rock shelter, radiocarbon dated between c. 7160 and
5610 cal yr BP, is a phase characterized by a fully cattle-based
economy, which included dairying as confirmed by the presence
of bones of Bos taurus (F. Alhaique, pers. comm.) and organic
residues on the potsherds (Dunne et al., 2012). Finally, strips of
ovicaprine dung and organic sands with cuvette hearths are the
evidence of specialized LP goat herders who used the site probably
during the winter season between approximately 5700 and
4650 cal yr BP.
Four more dates were obtained from samples collected directly
along the section of the North Sector (Fig. 5) which is studied in
detail in the present paper: one date, 5170 ±25 uncal yr BP (ovi-
caprid dung: 5990e5900 cal yr BP), comes from Unit I; Unit IV dates
to 7910 ±30 (seeds: 8800e8600 cal yr BP), Unit VI to 8410 ±30
(charcoal: 9520e9400 cal yr BP), and Unit VII to 8820 ±60 (char-
coal: 10,170e9670 cal yr BP). The archaeological content ensures a
strict correlation with the deposits inside the rock shelter.
4.2. Description of the sequences and sampling sites
4.2.1. Northern Sector (TK-NS)
The TK-NS filling is 1.6 m thick and lies upon the sandstone
bedrock of the rock shelter. The stratigraphic sequence has been
macroscopically grouped into main Units based on macroscopic
features, main unconformities and archaeological content (Biagetti
and di Lernia, 2013). The sampling of the sequence for laboratory
analyses was performed on the southern trench wall (Fig. 5,
Table 1), with additions from the northern wall.
From the top, there is Unit 0-NS, a thin layer of aeolian sands.
Unit I-NS (Middle Pastoral 2 or MP2) includes organic sand mixed
with dried and charred plant remains and several hearths. Unit II-
NS (Middle Pastoral 1 or MP1) is similar to Unit I-NS, though the
organic fraction is less recurrent and hearths and ash lenses in-
crease. Early Pastoral layers are represented in Unit III-NS, where
unhumified plant remains and coprolites have been observed
within an organic sand matrix. Late Acacus 3 (LA3) archaeological
contexts are included in Unit IV-NS. These are similar to Unit III-NS,
but they are characterized by larger hearths and ash dumps. Unit V-
NS (Late Acacus 2 or LA2) features lenses of undecomposed plant
remains, but planar and almost continuous slurry levels charac-
terize this part of the section. Unit VI-NS (Late Acacus 1 or LA1)
comprises loose sand with reducing plant remains. Unit VII-NS
(LA1) contains coarse light yellow sand, intermixed with well-
preserved plant remains and charcoal.
A vertical set of 26 pollen samples (at 5e10 cm intervals) plus 5
samples from lateral positions were collected from the southern
wall. Seven samples for micromorphological analyses were taken to
check specific contexts throughout the sequence (Fig. 5). Samples
for sedimentological analyses were collected in the vicinity of
pollen samples. To better appreciate lateralvariations in the deposit
and their environmental meanings, five other pollen samples were
also collected from the northern wall (two from Unit V-NS, samples
35 and 36; three from Unit VII-NS, samples 28e30), with one
sample for micromorphological analysis (no. 8, Unit V-NS).
Table 2
Description of the section of TK-WS, eastern wall (chronology according to Biagetti and di Lernia, 2013).
Unit Description Cultural phase Chronology
(cal yr BP)
0 Desert pavement veneered by pink (7.5Y 7/4) aeolian sand; isolated stones,
their exposed part is coated by a Mn-rich rock varnish; clear planar boundary
ee
I B21t horizon (cm 0e15); sandy loam, reddish yellow (7.5Y 7/6), few stones,
moderate discontinuously platy structure, moderately hard, undulated clear boundary
Middle Pastoral 2 6300e5750
II B22t horizon (cm 16e40); sandy loam, yellowish brown (10Y 5/4), rare to
common stones, weak platy to subangular blocky structure, slightly hard, clear boundary
Late Acacus 3 8950e8450
III 2A horizon (cm 41e70); sandy loam, dark grayish brown (10Y 4/2), rare
stones, massive, slightly hard, gradual boundary to
Late Acacus 3 (?) 8950e8450 (?)
2AC horizon (cm 71e80), sandy loamy sand, grayish brown (2.5Y 5/2), slightly hard
to soft, lower boundary not exposed
Table 1
Description of the section of TK-NS, southern wall (chronology according to Biagetti and di Lernia, 2013).
Unit Description Cultural phase Chronology
(cal yr BP)
0 Loose, pink (7.5YR 7/4) aeolian sand ee
I Organic loose sand, light grey (2.5Y 7/2); concave and planar lamination; common
vegetal remains, charcoal and coprolites; large stones from vault collapse; abrupt
erosive boundary sloping to the west
Middle Pastoral 2 6300e5750
II Organic sand, greyish brown to light olive brown or olive brown (2.5Y 5/2, 2.5Y 5/3, 2.5Y 4/4);
from loose to compact; planar bedding gently sloping to the west; frequent charred and uncharred
vegetal remains; lenses of white ash (10Y 8/1) and charred material; clear boundary
Middle Pastoral 1 6950e6300
III Loose thin laminated sand, very pale brown (2.5Y 7/2); frequent uncharred vegetal remains and
coprolites; abrupt linear boundary
Early Pastoral 1 8250e7800
IV Organic sand, greyish brown to light olive brown or olive brown (2.5Y 5/2, 2.5Y 5/3, 2.5Y 4/4);
from loose to moderately hard; planar bedding gently sloping to the west; frequent charred and
uncharred vegetal remains. Lenses of white (10YR 8/1) ash and black charred material. Some
large structural stones. clear (erosive?) concave boundary
Late Acacus 3 8950e8450
V Massive organic loose sand including two dark greyish black (2.5Y 4/2) thin layers of laminated
sand cemented by organic matter; clear boundary gently sloping to the west
Late Acacus 2 9450e8950
VI Loose sand, light olive brown (2.5Y 5/3); scarce vegetal fragments, often charred; planar bedding
slightly sloping to the west; clear planar boundary, interrupted to the west by a large stone structure
Late Acacus 2 9450e8950
VII Loose organic sand, olive brown (2.5Y 4/4); planar discontinuous bedding gently sloping to W; rare
vegetal remains distributed in thin layers; rare weathered sandstone fragments; in the east side planar
clear boundary to the bedrock, to the west affected by hardened filling of large stone structure
Late Acacus 1 9950e9450
M. Cremaschi et al. / Quaternary Science Reviews 101 (2014) 36e60 41
4.2.2. Western Sector (TK-WS)
The TK-WS deposit is rather homogeneous and almost massive; a
stone lineat the depth of c. 30 cm is the sole evidencefor stratification
in this part of the deposit. For that reason, the differentiation of
archaeological sub-phases is only considered tentative and, lacking
radiocarbon dates, given the absence of organic substance, was
determined mostly on the basis of the poor archaeological evidence.
The sequence was excavated to a depth of c. 90 cm without reaching
bedrock(Fig. 6,Tab le 2). It is characterized, from thetop, by Unit I-WS,
which isa layer displaying a lamellaraggregation,with archaeological
materials of Middle Pastoral age (MP2). Below it, a layer with a
lamellar aggregation (Unit II-WS) including materials of Late Acacus
age (LA3) is present. Unit III-WS is a thick layerof weathered aeolian
sand with bioturbation pedotubules and an archaeological disconti-
nuity signalled by the presence of Late Acacus materials in its upper
part. The deposit was systematically sampled: 12 pollen samples
were taken at 5e10 cm intervals, and four undisturbed samples of
sediment for thin sections were taken from each pedological horizon
distinguished in the three main Units.
4.3. Pedosedimentary and micromorphological analyses
Thin sections from undisturbed blocks, integrated with grain
size and routine chemicalephysical analyses on bulk samples, have
been used to identify the stratigraphic sequence-forming processes
and infer the environmental and anthropogenic factors for accu-
mulation and post-depositional changes (Courty, 2001; Goldberg
and Macphail, 2006; Goldberg and Berna, 2010). Oriented and
undisturbed sediment blocks from selected Units were collected as
described above. Thin sections (5 9 cm) were manufactured after
consolidation according to standard methods (Murphy, 1986).
Micromorphological observation under plane-polarized light (PPL)
and cross-polarized light (XPL) of thin sections employed an optical
petrographic microscope Olympus BX41 with a digital camera
(Olympus E420). For the description and interpretation of thin
sections, the reader should consider the terminology and concepts
established by Bullock et al. (1985), Stoops (2003) and Stoops et al.
(2010). Properties of each sample detected by thin section analysis
are summarized in Table 4.
Oriented samples for thin sections were collected from TK-NS
and TK-WS (Figs. 5 and 6). Bulk samples from the TK-NS were
also collected for textural and chemicalephysical analyses, the re-
sults of which are reported in Figs. 7 and 8. Applied methods are
summarized as follows. (i) Humified organic carbon was identified
following the Walkley and Black (1934) method, using chromic acid
to measure the oxidizable organic carbon (titration). (ii) Total
organic carbon was estimated by loss on ignition (LOI; Heiri et al.,
2001); samples were air-dried and organic matter was oxidized
Table 3
Radiocarbon dating results and calibration (according to Bronk Ramsey, 2009) from the Takarkori rock shelter (modified, Cherkinsky and di Lernia, 2013).
Laboratory number Stratigraphic
number
Description of
the context
Cultural
attribution
Material Uncalibrated
age
Calibrated years
BC (95%)
Calibrated years
BP (95%)
LTL670A H13 Burial Late Pastoral Human bone 4291 ±50 3090e2700 5040e4650
GX-31071 76 (pit) Item Late Pastoral Skin (sheep/goat) 4590 ±80 3630e3030 5580e4970
GX-30325 6 Dung Late Pastoral Dung 4800 ±70 3710e3370 5660e5320
LTL908A 24 Hearth Late Pastoral Coprolite 4841 ±50 3750e3510 5700e5460
UGAMS#8707 25 Organic sand Middle Pastoral Seeds 4970 ±25 3800e3660 5750e5610
LTL907A 22 Hearth Middle Pastoral Charcoal 5064 ±55 3970e3710 5920e5660
LTL362A 25 Item Middle Pastoral Skin (sheep/goat) 5070 ±35 3960e3780 5910e5730
UGAMS#10149 330 Organic sand Middle Pastoral Dung strip 5170 ±25 4003e3951 5990e5900
UGAMS#01843 374 Formal stone structure Middle Pastoral Collagen 5280 ±50 4240e3980 6190e5920
UGAMS#01841 25 Organic sand Middle Pastoral Collagen 5340 ±50 4330e4040 6280e5990
GX-31077 H9 Burial Middle Pastoral Bone collagen 5600 ±70 4600e4330 6550e6280
LTL367A 25 Organic sand Middle Pastoral Dung strip 5980 ±50 5000e4720 6950e6670
UGAMS#2852 25 Organic sand Middle Pastoral Enamel bioapatite 5980 ±70 5050e4710 7000e6660
GX-30324-AMS H1 Burial Middle Pastoral Human bone 6090 ±60 5210e4840 7160e6790
UGAMS#01842* 41 Organic sand Early Pastoral Collagen 6230 ±90 5470e4940 7420e6890
GX-31074-AMS H5 Burial Early Pastoral Human bone 6540 ±70 5630e5370 7570e7310
GX-31073-AMS H4 Burial Early Pastoral Human bone 6740 ±70 5760e5520 7710e7470
LTL1585A H11 Burial Early Pastoral Human bone 6763 ±55 5750e5560 7700e7510
GX-31075-AMS H6 Burial Early Pastoral Human bone 6900 ±70 5980e5660 7930e7610
LTL911A H10 Burial Early Pastoral Human bone 7068 ±100 6210e5730 8160e7670
GX-30326 41 Organic sand Early Pastoral Dung strip 7070 ±100 6210e5730 8160e7680
GX-31064 93 Floor Early Pastoral Soil 7130 ±100 6230e5800 8180e7750
GX-31076-AMS H7 Burial Early Pastoral Human bone 7130 ±70 6210e5840 8160e7790
LTL1586A H12 Burial Early Pastoral Human bone 7155 ±65 6210e5890 8160e7840
LTL914A H14 Burial Early Pastoral Human bone 7327 ±65 6370e6060 8320e8000
GX-31066 96 Organic sand Late Acacus Soil 7470 ±100 6490e6080 8440e8030
GX-31069 108 Hearth Late Acacus Soil 7580 ±110 6650e6230 8590e8180
LTL369A 38 Humified organic sands Late Acacus Charcoal 7694 ±60 6640e6440 8590e8390
GX-31070 123 Ash dump Late Acacus Charcoal 7730 ±100 7010e6390 8950e8340
LTL364A 150 Hearth Late Acacus Charcoal 7801 ±35 6700e6510 8650e8450
LTL365A 96/103 Organic sand Late Acacus Dung strip 7820 ±50 6820e6500 8770e8450
GX-31068 103 Organic sand Late Acacus Soil 7890 ±110 7060e6500 9010e8450
UGAMS#10148 337 Ash dump Late Acacus Seeds 7910 ±30 6842e6653 8800e8600
UGAMS#8708 359 Organic sand Late Acacus Seeds 7930 ±30 7030e6680 8980e8630
LTL910A H8 Burial Late Acacus Human bone 7973 ±45 7050e6690 9000e8640
LTL368A 96/103 Organic sand Late Acacus Charcoal 8031 ±65 7140e6690 9090e8640
GX-31065 129 Hearth Late Acacus Soil 8040 ±110 7310e6650 9260e8600
LTL366A 101 Hearth Late Acacus Charcoal 8049 ±40 7140e6820 9080e8770
GX-31067 103 Organic sand Late Acacus Soil 8080 ±110 7360e6670 9310e8620
GX-31072 136 Hearth Late Acacus Charcoal 8290 ±140 7600e6850 9550e8800
UGAMS#10150 351 Hearth Late Acacus Charcoal 8410 ±30 7553e7452 9520e9400
UGAMS#10147 344 Floor Late Acacus Charcoal 8410 ±30 7553e7452 9520e9400
UGAMS#01844 408 Hearth Late Acacus Charcoal 8820 ±60 8220e7720 10,170e9670
M. Cremaschi et al. / Quaternary Science Reviews 101 (2014) 36e6042
at 500e550
C to carbon dioxide and ash, then the weight lost
during the reaction was measured by weighing the samples before
and after heating. (iii) Conductivity, reflecting the concentration of
soluble salts, was performed by dispersing sediment in pure water
and was measured through a conducimeter. (iv) Grain size was
determined (diameter from 2000 to 63
m
m) through wet sieving
after removing organics by hydrogen peroxide (130 vol) treatment
(Gale and Hoare, 1991).
4.4. Pollen analysis
The 48 pollen samples collected from the TK-NS and TK-WS
(Figs. 5 and 6) were arranged into two main pollen sequences.
About 10e20 g of sediment (dry weight) were treated with
tetra-sodium pyrophosphate, sieved with a nylon 7
m
m mesh, and
treated with HCl 10%, HF 40%, acetolysis and heavy liquid separa-
tion (sodium metatungstate hydrate; Florenzano et al., 2012).
Fig. 5. Schematic representation of the EasteWest profile of the southern wall of the TK-NS; the position of radiocarbon-dated samples and results (uncal BP) are also indicated
(profile drawn by A. Monaco and S. di Lernia). Key: a); aeolian sand; b) sand rich in organic matter; c) lenses of undecomposed plaint remains; d) ash; e) charcoal; f) slurry deposit;
g) eroded sand from the wall; j) bedrock; location of undisturbed block for k) micromorphology and j) palynological samples.
Fig. 6. Schematic representation of the NortheSouth profile of the eastern wall of the TK-WS (profile drawn by A. Monaco and S. di Lernia). Key: a) lamellar structures; b) lamellar
aggregation; c) weathered sand including bioturbation pedotubules; d) micromorphological and e) palynological samples.
M. Cremaschi et al. / Quaternary Science Reviews 101 (2014) 36e60 43
Lycopodium spores were added to calculate pollen concentration,
expressed as pollen per gram (p/g). Permanent slides were moun-
ted with glycerol jelly. Pollen analyses were made at 400and
1000with immersion oil. About 340 (TK-NS) and 140 (TK-WS)
pollen grains per sample were counted on average. Pollen identi-
fication was based on the reference pollen collection and relevant
literature (Bonnefille and Riollet, 1980; Reille, 1992, 1995, 1998;
Ayyad and Moore, 1995). Some types were distinguished within
the Poaceae, i.e., the >40
m
m and larger pollen types, and the
18e26
m
m pollen of Phragmites with imperceptible punctae in a
scabratae exine (Hall, 1981).
Several floras are used here to determine habitus, distribution,
ecology and phytogeographical affinity of genera and species (Corti,
1942; Turril and Milne-Redhead, 1952; Maley, 1980, 2004; White,
1983; Ozenda, 2000; Watrin et al., 2009). The pollen nomenclature
follows the African Pollen Database. Percentages are calculated on a
pollen sum, which includes all pollen grains. Sums of the most
abundant taxa are calculated as ‘Dry’and ‘Wet’sums. The first sum
includes Asteraceae and Chenopodiaceae/Amaranthaceae, here-
after Chenopodiaceae, that are typical of dry environments; the
second sum includes Poaceae and Cyperaceae that are more
abundant under comparatively moist conditions (Fowell et al.,
2003; Herzschuh et al., 2004). The D/W ratio was used by
Hooghiemstra (1996) for vegetational shifts in marine cores, and
similar indexes are useful as crude indicators of main vegetational
changes: e.g., the ratio Artemisia to Cyperaceae is used to distin-
guish steppe to meadow vegetation in lake sediments (Li et al.,
2011); Cyperaceae to Poaceae is calculated in order to distinguish
the lake marginal from terrestrial source of pollen (Gillson, 2006);
Artemisia to Chenopodiaceae ratios help to discriminate between
steppe-like vegetation and desert-like environments and to infer
changes in moisture conditions (El-Moslimany, 1990). Some of
these indexes are useful tools for qualitative and semi-quantitative
palaeoenvironmental reconstruction (Herzschuh, 2007). In this
paper, the D/W ratio is used as an indicator of relative moisture
conditions based on the assumption that grassland vegetation
needs more humidity, whilst Chenopodiaceae and Asteraceae are
today the plant families that host the most common representa-
tives of desert vegetation in the Sahara and its fringes (Ozenda,
2000).
The sum of plants associated with wet environments includes
telmatophytes growing in the reed-bed belt (cattails: Typha domi-
ngensis-type, Typha latifolia-type, Typha minima-type, and reeds-
Phragmites-type) and a few floating aquatics (Lemna,Potamogeton).
Pollen diagrams, including the calculation of the zonation by cluster
analysis, were drawn with Tilia 2.0 and TGView (Grimm,
1991e1993).
5. Results
5.1. The pedosedimentary sequence
5.1.1. TK-NS
Grain-size cumulative curves (Figs. 7 and 8) indicate homoge-
neity in the mineral fraction of the deposits, as the grain size dis-
tribution along the studied sequence is almost identical to that
recorded at its base (Unit VII-NS). The latter deposit, too poorly
sorted to be of aeolian origin, originated from the disaggregation of
the friable Palaeozoic sandstone (fluvial and deltaic facies; El-ghali,
2005) in which this part of the rock shelter was excavated. A local
origin of Unit VII-NS sand is further supported by its olive-brown
colour, similar to the sandstone bedrock, but in contrast to the
dominant pink-reddish colour of the aeolian sand in the Takarkori
dune field and aeolian sand formations in the rock shelter's sur-
roundings. In the thin section, the sand granules in Unit VII-NS and
along the sequence are inhomogeneous in shape, associating
angular to rounded habits, and are related to angular lithorelicts;
this also excludes an aeolian origin of the deposits. Moreover,
quartz grains are not stained by a film of iron oxides, which is
common in local aeolian sand (Zerboni et al., 2011). However, the
percentage of the silt þclay fraction changes significantly along the
sequence (Figs. 7 and 8), reaching a peak in coincidence at the bases
of Units I-NS and II-NS (25% and 50%, respectively). Along the
sequence coarse sand is around 20%, but it decreases significantly
(c. 10e15%) in Units III and II and at the base of Unit I, while at its top
it increases again to c. 20e25%. Humified organic carbon, loss on
ignition and conductivity (Fig. 7) display similar, parallel trends.
This suggests that the amount of organic matter may control the
distribution of soluble salts and therefore play a main role in
determining the geochemical properties of the sequence. Organic
Table 4
Summary of the micromorphological properties of the samples from the TK-NS (N), TK-WS (W), and TK-MS (M) sectors of the excavation.
Unit Sample Sector Microstructure Coarse minerals Biogenic constituents Groundmass Related distribution Pedofeatures
S1 S2 S3 S4 M1 M2 M3 M4 B1 B2 B3 B4 G1 G2 G3 G4 R1 R2 R3 P1 P2 P3 P4
I TK1 Northern þRF CC CR þFþ R
II TK2 Northern þþRF RRC RR þF þ C
III TK3 Northern þþRC FCRþC þ
IV TK4 Northern þRRRR CF þ R
IV TK5 Northern þþRF C* C R R þ þ F
VI TK6 Northern þRF RC RR þRþ R
V TK7 Northern þþ FRC R R þCþ þ R
AC58 TK8 Main þþRF RC R C R þRþ R
Bt21 W1 Western þþCF R R** Rþþ þ CC
Bt22 W2 Western þþCF R** þþ þ C
2A W3 Western þRF Rþ R****
2AC W4 Western þRF R*** þ
Microstructure: S1, bridged grain structure/single grain structure; S2, intergrain microaggregate structure; S3, platy structure (trampling); S4, laminated structure (sedi-
mentary, colluvial). Coarse mineral components (>250 microns): M1, lithorelicts (sandstone fragments); M2, medium and coarse rounded and subrounded quartz grains; M3,
pedorelicts; M4, pottery fragments. Biogenic components: B1, vegetal fragments; B2, charcoal (>500 microns); B3, coprolites; B4, bone fragments. Groundmass: G1, undif-
ferentiated to poorly b-spekled b fabric; G2, punctuated organic fabric or organic pellets; G3, birefringent fabric; G4, crystallitic fabric. C/F related distribution: R1, chitonic; R2,
close porphyric; R3, monic. Pedofeatures: P1, pathches of phosphate (apatite); P2, impregnative features: calcitic concretions and pendents; P3, impregnative features:
pseudomorphic calcite aggregates, ash connected; P4, texturale pedofeatures: dusty lamimated clay coatings. *Charred vegetal fragments; **finely subdivided charcoal; ***fish
bones; ****isotic. Estimated concentration: R, rare (<15%); C, common (16e30%); F, Frequent (31e>50%).
M. Cremaschi et al. / Quaternary Science Reviews 101 (2014) 36e6044
matter content and chemical parameters (Fig. 7) show higher
concentration in the upper part of the sequence and a significant
peak in correspondence in Unit II-NS; they then decrease, showing
a saw-tooth pattern in Units IV-NS and V-NS and a more regular
trend in Unit VI-NS, reaching the lowest values in Unit VII-NS.
From the micromorphological point of view (Table 4), unde-
composed plant fragments and coprolites dominate the whole
sequence, whose matrix is made of coarse mineral components
(Fig. 9). They are associated with many spherulites and phytolith
chains (these elements are almost ubiquitous and therefore not
specifically mentioned in Table 4). In one case (Unit IV-NS), plant
fragments suffered sin-depositional biological activity, and unde-
composed pellets largely dominate the thin section. Humified
organic matter in the shapes of intergranular isotic fillings and
punctuations occur in several cases, and it is particularly developed
in sample 7 (Unit V-NS), which was collected in correspondence
with a planar organic-rich layer described in the field as a ‘slurry’
deposit. Calcite micro- and macro-crystals, providing some evi-
dence for re-crystallization, are related to ashes and often occur in
association with macroscopic evidence for hearths. Bioturbation is
particularly evident in the inner part of the rock shelter, at the
interface between its vault and the deposit; thin section AC58 from
Unit V of the Main Sector showed a large number of voids related to
invertebrate bioturbation. In this part of the excavation (at the
interface with the sandstone wall), sand grains are distributed in
discontinuous upward-finning laminae and a larger redistribution
of calcite and soluble salts also occurred (Fig. 10), as confirmed by a
diffuse crystallization (impregnation) of the groundmass. Qualita-
tive X-ray diffraction analysis highlights the occurrence of domi-
nant potassium nitrate (KNO
3
), quartz, and, in very limited quantity
of calcium carbonate.
Mineral and biological components of different sizes are
frequently redistributed by discontinuous planar lamination due to
occupation trampling (Courty et al., 1989; Matthews et al., 1997).
However, the sand grains in Units VI-NS and VII-NS are distributed
in discontinuous upward-finning laminae, testifying for water
transportation originating from colluvial processes (Fig. 10). These
features are in accordance with the discontinuous planar non-
parallel bedding that is macroscopically observed.
5.1.2. TK-WS
This sector is located beyond the drip line. Lateral continuityand
archaeological content permit a strict correlation between the NS
and WS sequences, but their pedosedimentary properties differ. No
plant macro-remains were observed in the WS sequence, either in
the field or thin sections. The dark colour of the deposit confirms
the presence of highly humified organic matter. The sequence may
thus be interpreted as a soil profile (Fig. 6), composed of two su-
perposed laminar horizons (B21t, B22t, which represent Units I-WS
and II-WS, respectively) below the desert pavement, covering
organic horizons (2A and 2AC, which constitute Unit III-WS).
At the micromorphological level, the microstructure of the B21t
and B22t horizons (Units I-WS and II-WS) consists of discontinuous
planar gradated laminae (Fig. 11), indicating a contribution of
colluvial processes and water washing in to form the parent ma-
terial of these horizons. Furthermore, clay illuviation in
Fig. 7. Results of sedimentological analyses (grain size, humified carbon, loss on ignition, conductivity). The main stratigraphic Units are also indicated, while dots represent the
sampling spots for sedimentological analyses.
Fig. 8. Selected cumulative grain size curves for samples collected along the section of
the TK-NS.
M. Cremaschi et al. / Quaternary Science Reviews 101 (2014) 36e60 45
intergranular voids is represented and displays a lamellar distri-
bution pattern (Fig. 11); in the surface horizon calcite concretions
also occur. In the 2A and 2AC horizons (Unit III-WS), former
anthropogenic organic content is indicated by rare charcoal and
weathered bone fragments (possibly including fish bones). No plant
fragments were observed, and the humified organic matter formed
the isotic groundmass distributed in the intergranular spaces
(Fig. 11).
Fig. 9. Photomicrographs of herbivore coprolites and vegetal fibres from the upper part of the stratigraphic sequence. A) Detail of a well preserved coprolite (Unit I-NS, PPL) and a
detail (B) of spherulites (XPL); C) fragmented coprolites from Unit III-NS mixed to vegetal fibres (PPL); D), detail of (C) showing the platy distribution of fibres and spherulites (XPL).
Fig. 10. Photomicrographs of selected micro-features from TK-MS and TK-NS sectors. A) Sample AC58 Unit V-MS (PPL), note the crescentic distribution of organics; B) sample AC 58
Unit V-MS soluble salts (niter) and calcite impregnations in the groundmass (XPL); C) sample 6 Unit VI-NS showing gradated distribution of the coarse mineral fractions (PPL); D)
sample 7 Unit V-NS (slurry layer), intergranular organic matter concentrations with planar distribution due to trampling (PPL).
M. Cremaschi et al. / Quaternary Science Reviews 101 (2014) 36e6046
5.2. Palynological analysis
Pollen preservation and floristic richness are different in the
sequences of the TK-NS and TK-WS sectors. Spectra (Figs. 12e14)
are characterized by low tree pollenvalues, which give evidence for
sparse tree cover and grass dominance near the rock shelter. The
co-presence of pollen from plants living in ecologically wet and in
arid environments (Fig. 15) indicates that local and regional signals
of different vegetation types, also simultaneously living in the area,
are represented in the spectra. Human and animal plant transport
inside the rock shelter is mainly inferred by two evidences: i) at the
macroscopic level: an impressive quantity of undecomposed plant
remains was observed in the layers, including high quantity of
seeds/fruits and plant remains that were sorted by dry sieving or
picked up collection (Olmi et al., 2011; Biagetti and di Lernia, 2013);
further, thanks to ii) the microscopic analysis very high percentages
and concentrations of pollen from useful plants (e.g., Typha and
Artemisia) were observed in slides from similar deposits of the
Teshuinat area (Mercuri, 2008a).
Since it is known that pollen spectra from archaeological sites
(on-site) are strongly influenced by human activities, reconstruc-
tion of plant cover and inferences regarding climate are problem-
atic. In such contexts, humans and their animals continuously
transported the pollen produced by plants living in the 'range of
influence of the site' (Mercuri et al., 2012); this occurred through
plant harvesting or by involuntary collection of dust by feet and
skin, or by coprolites (Dimbleby, 1985; Faegri et al., 1989). There-
fore, pollen accumulated by anthropogenic transport does not
reflect only edaphically restricted plant communities, as typically
occurred in natural sites near wadis (Mercuri, 2008b). Though
over-representation of some pollen types is evident in single
samples of the Takarkori sequence, the analysis of many samples
from one layer/Unit helps to obtain reliable palaeoenvironmental
interpretations based on average data per phase (zone). The
anthropogenic pollen, discussed within a multidisciplinary
perspective, is useful for environmental reconstructions because
humans must have collected plants in the wild, and changes in
plant selection must have relied on changes in the environment
shared by plants and humans.
In the following subsections, pollen zones and sub-zones of the
two sequences are reported with the corresponding stratigraphic
Units and archaeological cultural phase, obtained from the inter-
disciplinary investigations on the site. If not differently reported,
pollen percentages are mean values of the zone or sub-zone, and
interpretation relies on the mean average changes per zone/sub-
zone to avoid the one-sample over-representation bias.
5.2.1. The TK-NS pollen sequence
Folded grains are common, but pollen is prevalently well pre-
served, especially in samples of older age. Only sample 15, corre-
sponding to an ash layer, is sterile. Pollen concentrations are
approximately 120,000 p/g on average, a very high value that
mirrors the human action of on-site plant accumulation (Mercuri,
2008a). Pollen clumps are frequent, particularly in samples with
very high concentrations. They indicate the deposition of
blooming plants or the presence of dung or faeces (Fægri and
Iversen, 1989).
The floristic list contains 92 pollen taxa, including 28 woody
taxa. Poaceae-grasses are dominant (63%, including 9% of >40
m
m
pollen). The Asteroideae-daisy family (11%, mainly Artemisia 4%),
Cyperaceae-sedges (4%), Chenopodiaceae-chenopods (3%) and
Brassicaceae-cabbage family (1%) are common. Only Tamarix-
tamarisk (4%) has a significant value among the trees (8%). Hy-
grophilous plants (8%) include the telmatophytes Typha-cattails
(3%) and Phragmites-type-reeds (2%) while aquatics include water-
floating plants such as Potamogeton and Lemna.
Fig. 11. Photomicrographs from TK-WS. A) Sample 1, Unit I-WS (B21t horizon), gradated distribution of coarse mineral fraction due to colluvial process (PPL); B) sample 2, Unit II-WS
(B22t horizon), laminated clay coating related to intergranular voids (XPL); C) sample 3, Unit III-WS (2A horizon), minute fragments of bones in the mineral groundmass (PPL); D)
sample 3, Unit IV-WS (2A horizon), enaulic related distribution of organic matter (PPL).
M. Cremaschi et al. / Quaternary Science Reviews 101 (2014) 36e60 47
Fig. 12. Percentage pollen diagram of the profile TK-NS, selected taxa.
M. Cremaschi et al. / Quaternary Science Reviews 101 (2014) 36e6048
Two main pollen zones and six subzones are recognized, start-
ing from the bottom (Figs. 11 and 12).
5.2.1.1. Zone Tk 1 (18 samples, from c. 135 to 71 cm; Units VII-NS to
IV-NS; archaeological context Late Acacus). Pollen concentration is c.
51,000 p/g, matching the low organic matter content found in
sedimentological analyses. The tree percentage is low (11.5%; 5.0%
excluding Tamarix). The more abundant or exclusive taxa to this
zone are Tamarix, Capparaceae (Capparis,Maerua-type, Boscia-
type), Hyphaene,Maytenus and Salvadora among trees, and Apia-
ceae, Asteraceae (Ambrosia-type maritima,Artemisia,Centaurea-
type, Cichorieae), Commelina-type, Tribulus terrestris-type, Zygo-
phyllum. Most are part of a sparsely wooded savannah vegetation
that was present together with grassland habitats. The D/W ratio is
very low (0.3; 0.1 excluding Artemisia), suggesting that savannah is
more represented than xerophilous vegetation in pollen spectra.
The wet environments are represented by herbaceous telmato-
phytes and aquatics (3.7%) as well as tamarisk (6.6%).
5.2.1.1.1. Subzone Tk 1a (5 samples, from c. 135 to 120 cm; Unit
VII-NS). Pollen concentrations are the lowest of the sequence.
Potamogeton-pondweed, with its highest value in the sequence,
marks the presence of wet environments, with reeds and cattails
(especially Typha domigensis-type) growing in marginal zones of
lakes, rivers and ponds. Considering the low pollen production of
pondweeds that have wind or water pollination (Zhang et al., 2010),
this aquatic plant is a good indicator of local permanent freshwater
habitats. The psammophilous shrub Cornulaca monacantha-type is
absent. There are significant values of Tamarix (up to 31%), Capparis,
and scent plants like Artemisia,Mentha-type and other Lamiaceae.
As they typically have been recorded in fairly coeval layers from
other rock shelters and caves of the Tadrart Acacus, they are
anthropogenic pollen indicators representing medicinal and food
plants harvested by hunteregatherers (Mercuri, 1999, 2008a).
5.2.1.1.2. Subzone Tk 1b (6 samples, from c. 119 to 101 cm; bottom
of Unit VI-NS). Mean values of plants from wet environments in-
crease, especially those form marginal zones likeT. latifolia-type. This
could be regarded as a widening of shallow-water marginal zones or
general water level lowering. Grassland also decreases, while
xerophilous plants increase, and Cornulaca monacantha-type is pre-
sent with Urtica-type. The tropical-Sahelian Acacia,Boscia-type and
Maerua-type are present, and the Capparaceae have maximum
values. Tamarix has a second peak (46%), and scent-medicinal plants
are still significant (Myrica besides Artemisia and other Asteraceae).
5.2.1.1.3. Subzone Tk 1c (7 samples, from c. 100 to 71 cm; top of
Units VI-NS, and V-NS to IV-NS). Evidence for wet environments is
low: the lack of pondweeds suggests that this plant was not so
available in the area as it was previously, and therefore the further
reduction of permanent water bodies had occurred. Oscillations of
xerophilous plants are complementary to those of grasslands
(Fig. 12). Cyperaceae pollen reaches values, on average higher than
previously, that remain fairly steady until the top of the diagram.
Tamarix nearly disappears. In this subzone, pollen spectra possibly
mirror a period of environmental instability (bottom part), and the
exploitation of different natural resources. The cultural shift toward
new plants is visible in the second part of this subzone through the
abandonment of Artemisia and especially through the change in the
harvesting of wild cereals. This is evident in the spectra from the
notable increase of large pollen types, belonging to some Panicum as
well as Echinochloa and Setaria species, as visible in coeval sites
(Mercuri, 2008a). The rapid oscillation of D vs. W sums in the bottom
part may also be explained by an increased seasonality that made
available different plant resources in different seasons (Fig. 13).
Fig. 13. Percentage pollen diagram of the profile TK-NS, pollen sums and concentrations. Zonation is calculated with Tilia (CONISS ¼Constrained Incremental Sum of Squares).
M. Cremaschi et al. / Quaternary Science Reviews 101 (2014) 36e60 49
Fig. 14. Percentage pollen diagram of the profile TK-WS, selected taxa, pollen sums and concentrations. Zonation is calculated with Tilia (CONISS).
M. Cremaschi et al. / Quaternary Science Reviews 101 (2014) 36e6050
5.2.1.2. Zone Tk2 (14 samples, from c. 70 to 6 cm; Units III-NS to I-NS;
archaeological context Early and Middle Pastoral). Pollen concen-
trations quadruplicate to c. 207,000 p/g, suggesting high plant
accumulation in this zone. This matches the peak of organic matter
found in the upper part of the sequence (Figs. 6 and 12). The
anthropogenic transport (by humans and animals) of plants inside
the rock shelter is especially visible in the increase in grasses (food
and pasture plants). In these spectra, the tree percentage notably
decreases (3.3%; 2.6% excluding Tamarix). Acacia (0.6% vs. 0.1% in
Tk1) and Ficus among trees, together with Fabaceae including
Astragalus, and Heliotropium,Paronychia and Plantago are more
abundant or exclusive to this zone. Capparaceae, Tamarix,Artemisia
and Zygophyllum became insignificant, signalling a general reduc-
tion in the dry savannah vegetation. The D/W ratio (0.1) shows that
xerophytes were fairly negligible in spectra, while plants reflecting
wet conditions are better represented. Hygrophilous trees are low
(tamarisk and fig tree amount to 0.8%). The hygro-hydrophilous
pollen sum is somewhat better represented than previously
(5.6%; Fig. 13), with higher T. latifolia-type and Lemna added to
Potamogeton among floating plants; its value is largely due to the
Fig. 15. Well-preserved pollen grains from the TK-NS sequence. Key: A and B) Poaceae, large pollen >40
m
m (pollen zone Tk1); C) Poaceae and phytolits (Tk1); D) Ficus (Tk2); E)
Cyperaceae (Tk2); F) Typha latifolia type (Tk1); G) Cichorieae (left) and Brassicaceae (right) (Tk1).
M. Cremaschi et al. / Quaternary Science Reviews 101 (2014) 36e60 51
M. Cremaschi et al. / Quaternary Science Reviews 101 (2014) 36e6052
Phragmites-reeds that grow in the shallow-water marginal zones of
ponds or rivers. The Cyperaceae percentage is also higher (5.2% vs.
3.0% in Tk1).
5.2.1.2.1. Subzone Tk 2a (2 samples, from c. 70 to 60 cm; bottom of
Unit III-NS). Pollen concentrations are very high, suggesting that
there was an intensive plant accumulation. However, the collected
wild cereals do not include such abundant large pollen species as
the previous sub-zone (Tk 1c). As pollen of plants from wet envi-
ronments (mainly Phragmites) prevails over pollen of xerophytes,
this event probably occurred during a wet phase favouring the
spreading of grasslands.
5.2.1.2.2. Subzone Tk 2b (7 samples, from c. 59 to 30 cm; top of
Units III-NS, II-NS, and bottom of Unit I-NS). Pollen concentrations
are unevenly high. The increase of Potamogeton suggests that per-
manent freshwater bodies spread again. As xeric environments also
spread, a mosaic of diverse habitats was present during this phase.
Poaceae include a high quantity of different large pollen grasses in
the archaeological deposit, due to increased natural availability and
the cultural selection of ‘new’wild cereals used as fodder. These
were either transported and consumed within the rock shelter or
consumed elsewhere and excreted at the site by domestic flocks.
5.2.1.2.3. Subzone Tk 2c (5 samples, from c. 29 to 6 cm; top part of
Unit I-NS). Pollen concentrations decrease notably. A significant
change toward environmentally dry conditions is evident. Two
acacias (Acacia,Acacia ehrenbergiana-type), with a slight increase of
Tamarix and Maerua-type, mark the diffusion of dry savannah.
Accordingly, xerophytes (D sum) increase while grasses decline.
The tendency has a reverse trend only in the top sample. Though
the recovery of pollen of hygro-hydrophytes indicates that wet
environments were still present, they must have decreased in size.
In fact, there is an isolated presence of Lemna, and telmatophytes
also tend to diminish. Astragalus, with other Fabaceae, Echium,
some Asteraceae, Brassicaceae and Caryophyllaceae, represent the
plants brought into the rock shelter as fodder or deposited with
furs, hooves and excrements. In particular, milk vetches and viper's
bugloss herbs have been found as common parts of animal diets
and are prevalent in dung layers as evident in other coeval sites
(Trevisan Grandi et al., 1998). Plantago and Urtica-type come from
trampled areas and places enriched by faeces/dung/coprolites by
pastoralists and their animals (Giraudi et al., 2013).
5.2.2. The TK-WS pollen sequence
Due to the intense humification, pollen is preserved in low
quantities in this sector; thinned exines are common, and some
pollen grains are folded or crumpled. Post-depositional disturbances,
including hydratationedehydratation cycles confirmed by the geo-
archaeological analyses, may have determined the deterioration of
most pollen grains. Four samples are sterile (2, 6, 11, and 12), and
concentrations are decidedly lower than in TK-NS (2300 p/g on
average, with five samples <1000 p/g). In TK-WS, the floristic list is
reduced by half to 50 pollen taxa, including 13 woody taxa (Fig. 14).
Poaceae-grasses are dominant (58%) as in the TK-NS sequence,
but a lower percentage of pollen >40
m
m (1%) was found. With
Cyperaceae-sedges (10%), they are most likely more representative
of the vegetation cover rather than plant harvesting: this, however,
is evident because anthers (i.e., flowers) of grasses were observed.
The Asteroideae-daisy family (3%, with traces of Artemisia 0.1%) is
relatively low, and the Chenopodiaceae-chenopods (0.7%) and
Brassicaceae-cabbage family (0.3%) are insignificant. Tamarix-
tamarisk (0.1%) is also rare, while Acacia-acacia is only found
overrepresented in the top sample (see below). Hygrophilous
plants (12%) are mainly represented by Typha-cattails (10%).
Though there are few samples, 3 pollen zones and 4 sub-zones
may be distinguished from the bottom on the base of their strati-
graphic distribution and archaeological content (Fig. 14).
5.2.2.1. Zone Tkw 1 (4 samples, from c. 65 to 35 cm; Unit III-WS; AC
109, Late Acacus). The zone has relatively high taxa diversity,
including Chenopodiaceae (1%), Asteraceae (4%) and Typha (7%).
The two bottom samples (Tkw 1a) show low pollen concentrations,
higher amounts of Aster-type and less Poaceae than the other two
samples (Tkw 1b). Xerophilous plants and a drier environment are
especially represented at the bottom of the sequence. A mosaic of
habitats coexisted at this phase, attesting to a trend from relatively
drier to wetter environmental conditions.
5.2.2.2. Zone Tkw 2 (3 samples, from 30 to 12 cm; Unit II-WS; AC 89,
Late Acacus 3). Chenopods are absent, and there are traces of
Asteraceae (0.4%). A very high percentage of Typha (43%) with high
pollen concentration was found in the bottom sample (Tkw 2a),
which is evidence that this plant was transported to the site.
Without this over-representation, the percentages of this sample fit
those of other samples in the zone (Tkw 2b). Poaceae (69%) and
Cyperaceae (15%) represent grassland as the main vegetation of this
phase.
5.2.2.3. Zone Tkw 3 (1 sample, 5 cm; Unit I-WS; AC 83; Middle Pas-
toral 2). The top sample has a very low pollen concentration, and
plants from wet environments are not represented. The spectrum is
dominated by Acacia ehrenbergiana-type, suggesting the presence
of dry savannah during the deposition of this layer. The low pollen
content reflects both a low plant cover and the spread of low
pollen-producing species that grew in the area during an arid cli-
matic phase.
6. Discussion
6.1. Natural and anthropic factors in formation processes
Stratigraphic sections in the Takarkori fill differ mainly because
of their location (e.g., under or outside the rock shelter vault) and
subsequent exposure to rainfall. Water percolation through the
deposit, though climatically limited since the Middle Holocene
transition, primarily controlled the state of preservation of the
organic components of the deposit (including humified ground-
mass, finely subdivided remains, and plant fragments) and drove
their transformations. The organic coarse material was almost
completely removed from the TK-WS deposits, and it only survived
Fig. 16. Comparison between the signals of regional proxies for Holocene climate changes in North Africa. The vertical grey bars indicate the climate anomaly at c. 8200 cal yr BP
(according to Thomas et al., 2007) and the end of the AHP respectively. The chronology is expressed in cal yr BP. (A) Cultural phases at Takarkori (di Lernia and Tafuri, 2013; Biagetti
and di Lernia, 2013); (B) pollen record from the Takarkori rock shelter: the solid curve indicates desert taxa (Asteraceae þChenopodiaceae), the dashed one hydro-hygrophilous
taxa; (C) pollen record for the Wadi Teshuinat area (central Tadrart Acacus): the solid curve indicates desert communities and psammophilous, the dashed one taxa of wet en-
vironments (Mercuri, 2008b); (D) lake-level fluctuations in the central Sahara (Zerboni, 20 06; Zerboni and Cremaschi, 2012); (E) calcareous tufa sedimentation in the Tadrart Acacus
massif (Cremaschi et al., 2010); (F) width of tree rings of Cupressus dupreziana from the central Sahara (Cremaschi et al., 2006); (G) phases of high stand of Lake Gureinat in Sudan
(Hoelzmann et al., 2010); (H) activity of Nubian lakes (Hoelzmann, 2002); (I) deposition of Sapropel S1 in the eastern Mediterranean (Ariztegui et al., 2000); (J) sum of tropical
pollen types, lake Yoa Chad (Kr€
opelin et al., 2008); (K) Lake Qarun level changes in the Fayum Depression (Hassan, 1986); (L) Lake Chad lake-level changes (Servant, 1983); (M)
terrigenous (Ti) input to Lake Tana (Marshall et al., 2011); (N) Bahr El-Ghazal depression lake-level changes (Servant and Servant-Vildary, 1980); (O) Lake Abh
e level changes in
eastern Africa (Gasse, 1977); (P) evolution of Lake Bosumtwi in Ghana (Shanahan et al., 2006); (Q) Sahara dust record off Mauritania (deMenocal et al., 2000); (R) the
d
18
O record of
the Greenland NGRIP ice core (North Greenland Ice Core Project Members, 20 04); (S) mean summer insolation at 20N(Berger and Loutre, 1991).
M. Cremaschi et al. / Quaternary Science Reviews 101 (2014) 36e60 53
in the lower Unit III-WS (2A and 2AC horizons) in the form of
very small fragments of charcoal and bones. The redistribution
of humified organic matter along the profile, determined by the
isohumic process (Duchaufour, 1983), which required wet envi-
ronmental conditions, began in the LA period according to the
archaeological material present in the sequence. Pollen analysis
indicates humid habitats and sparse shrubby grassland vegetation
during this phase. Wet conditions are also suggested by the
occurrence of fish bone fragments found at the sequence base,
which are related to the lake and other ponds as indicated by
geomorphological and archaeological survey of the region and that
was active in the depression close to the Takarkori rock shelter at
that time (Fig. 2).
The colluvial features observed in the B21t horizon (Unit I-WS)
required that vegetation cover provided weak protection for the
soil surface and a water flux, even not regular throughout the year,
on the topsoil. The removal of the organic matter in the B21t (Unit I-
WS) and B22t (Unit II-WS) horizons promoted clay translocation
along the profile and lamellar argillic horizon formations. These
processes are related to the desert pavement formation at the soil
surface. This is not due to wind erosion and consequent deflation,
but instead depends on continuously incorporating dust and the
migration of the fine fraction inside the soil (Wells et al., 1995; Amit
et al., 2011). This process predates the onset of the current hyper-
arid conditions in the area. The exposed parts of the stones
included in the desert pavement are covered by black varnish,
whose initial formation dates to c. 5500 cal yr BP (Cremaschi, 1996;
Zerboni, 2008), by which time the pavement thus already existed.
Its formation and the development of the underlying soil occurred
due to the persistence of weak precipitation in a scenario of general
decline of vegetation cover.
The processes involved in the formation of the stratigraphic
sequence inside the rock shelter (within the limit of the drip line)
are rather different. The mineral fraction with coarse and medium
sand is derived from the degradation of the rock shelter vault and
wall and may be ascribed to slight thermoclastism and alternating
dry and wet cycles. No significant aeolian input was recorded at any
level of the sequence. Oxidizable carbon content versus loss in
ignition indicates a continuous supply of organic matter
throughout the section and a slow degradation rate. Due to the
limited presence of water inside the rock shelter, the high amount
of organic matter generated by the anthropogenic activities acted
as a buffer for preserving plant remains and other features related
to anthropogenic activities, including buried corpses, coprolites,
food residues, ecofacts, and artefacts on perishable materials (Tafuri
et al., 2006; di Lernia et al., 2012; Dunne et al., 2012; di Lernia and
Tafuri, 2013), and even nucleic acids of plants (Olmi et al., 2011).
Along the sequence, post-depositional bioturbation is rare, as
confirmed by thin section analysis, indicating that the micro-
environment of the deposit was barely suitable for invertebrate
fauna activity. Evidence of bioturbation was only observed in
sample AC 58, which was collected at the interface between the
deposit and the sandstone wall where fissures and drip provided
oxygenation and water availability, allowing for biological activity
and solute precipitation (e.g., niter eKNO
3
). Human activities must
therefore be considered as the dominant formative factor for the fill
inside the rock shelter (with the supply of the coarse mineral
fraction from the disaggregation of the cave roof and walls). It is
likely that processes related to human activities played a main role
in obscuring possible environmentecontrolled sedimentary and
post-sedimentary processes.
The colluvial features recorded in Units VI-NS and VII-NS, at the
base of the sequence, constitute the sole exception to this conclu-
sion, and they indicate high water availability in this period, which
is consistent with pollen analyses. Similar evidence for colluvial
processes was also observed in the deposits at the base of Uan
Afuda dating to 11,245 and 10,740 cal yr BP (Cremaschi and di
Lernia, 1999b). Conversely, the Early Pastoral deposits at the
Takarkori rock shelter are less humified than the nearly contem-
poraneous anthropogenic layers at the base of the sequence at the
Uan Muhuggiah rock shelter (Cremaschi, 1998), underlying the role
of stational factors in determining the characteristics of rock shelter
fillings in the area. Furthermore, the increase of the coarse sand
fraction at the top of Unit I fits well with pollen data, which in-
dicates for the same unit dry environmental conditions. This should
be attributed to a relative decrease in the organic fraction and notto
an aeolian input, given the grain size distribution.
6.2. Palaeovegetational reconstruction
Despite the strong anthropogenic influence on deposit formation,
taphonomic features and the pollen record of the Takarkori rock
shelter are highly informative about the local and regional palae-
ovegetational and palaeoenvironmental conditions (Fig. 16). The
pollen zones, in fact, describe primary and varied habitat conditions.
By considering the archaeological stratigraphyand radiocarbon dates,
the zones may be attributed to subsequent chrono-cultural phases
and vegetational events ranging from c. 10,000 to 4500 cal yr BP.
The Tk-NS pollen sequence shows that in the LA phase, at c.
10,000e8100 cal yr BP, the plant cover was largely constituted by
grassland and less so by sparsely wooded savannah vegetation.
Permanent freshwater habitats with floating pondweeds, and reeds
and cattails on the marginal zones, were common. A fairly diver-
sified set of food and other useful plants were available for gath-
erers to harvest (Tk1a). A widening of shallow-water marginal
zones or a general lowering of the water level was recognized
during the LA2 phase (Tk1b), while the xerophilous plant presence
began to expand. A further reduction of permanent water bodies is
visible at the end of the LA3 phase (c. 8300e7900 cal yr BP; Tk1c),
when environmental instability, seasonality and changes in plant
exploitation are evident.
At c. 8000e7000 cal yr BP (in the EP phase, Tk2), a significant
increase in accumulation of both food and fodder/pasture plants is
registered in pollen spectra. Although wet conditions were still
present, increased seasonality made the environment more artic-
ulated or changeable than was the case previously. Wet habitats
became smaller or were seasonally reduced, while Asteraceae and
Chenopodiaceae spread. The selection of ‘new’wild cereals used as
fodder suggests that new resources were available and substituted
the previous ones. Acacias and other xerophytes spread, matching a
significant change toward dryness at c. 6900e5500 cal yr BP (MP
phase, TK2c). A variety of habitats coexisted, while the establish-
ment of very dry environmental conditions and desert savannah
was evident at the time of the Middle Holocene transition (Tkw3).
6.3. Palaeoclimatic inferences and correlations
6.3.1. Palaeoclimate at Takarkori
Most of the palaeoenvironmental information comes from the
deposits preserved inside the rock shelter. Comparing the inner and
the outer sequence it is clear that in the latter post-depositional
processes strongly affected the state of the organic matter, which
is well preserved in the inner part. Also, the concentration of pollen
grains is substantial inside the rock shelter (TK-NS), while poor
outside of the shelter vault (TK-WS). Besides the local palae-
oclimatic significance, this evidence is further proof that pollen
data from Saharan archaeological sites are more informative in
palaeoclimatic studies when they are preserved within well pro-
tected sequences, while the interpretation of pollen spectra ob-
tained from open air archaeological contexts in dry conditions may
M. Cremaschi et al. / Quaternary Science Reviews 101 (2014) 36e6054
be less informative or much more problematic (Horowitz, 1992;
Mercuri, 2008b).
In the inner part of the rock shelter, the significant mean value of
plants from permanent freshwater habitats and the comparatively
low values of chenopods and psammophilous shrubs clearly
highlights that layers were deposited under environmental condi-
tions marked by the occurrence of widespread freshwater ecosys-
tems. In this area, these pre-dated the current Late Holocene
hyperarid phase (e.g., Gasse, 2000; Mercuri, 2008b; Cremaschi and
Zerboni, 2009; Watrin et al., 2009).
Unit VII and part of Unit VI, corresponding to pollen zone TK-NS,
includes the Tk1a, which lies upon the disaggregated and friable
sandstone bedrock; the Units preserve evidence for the first human
frequentation of the Takarkori rock shelter. During this phase, at
around 10,000 cal yr BP, the LA hunteregatherers occupied an
empty rock shelter. The micromorphological evidence for redistri-
bution of sediments after runoff indicates a high availability of
water. In fact, in the region at that time monsoonal precipitation
recharged the surface aquifers in the Tadrart Acacus and sur-
roundings (Cremaschi et al., 2010; Zerboni and Cremaschi, 2012).
Sparsely wooded savannah vegetation with grassland habitats
spread. In the first phases of occupation of the site, human groups
lived near wet habitats, where pondweeds floated in the water
surface of freshwater ponds or rivers, and cattails grew at the
margins and in wet soils. Harvesting of plants for food, medicine
and other purposes was centred not only on grasses, but also on a
wide range of vegetal species including tamarisks, capers, and scent
plants such as Artemisia and Mentha-type; plant remains were
carried to and processed in the rock shelter.
Units VI (upper part), V and IV (pollen zones TK-NS: Tk1b, Tk1c)
were formed during the LA2 frequentation. Sediments dating to
this period are slightly richer in organics, attesting to a more
intense occupation of the site, while pollen spectra show a decrease
of grassland, acacias and other tropical trees. The spread of cattails
can be explained by a general loweringof lake levels or widening of
shallow-water marginal habitats near the site, which is a confir-
mation of a general trend towards decreasing monsoonal water
supply to the central Sahara recorded by carbon and oxygen stable
isotopes of the calcareous tufa of the Tadrart Acacus (Cremaschi
et al., 2010). There is evidence of increasing aridity at the end of
this sub-phase, characterized by the local reduction of permanent
water bodies and mixed vegetation cover, with a relevant increase
of xerophilous plants to the detriment of grassland. Even though
the Takarkori sequences do not display a decisive interruption in
sedimentation and human occupation is rather continous, this
phase might correspond to the environmental crisis related to the
8.2 ka BP event (Alley et al., 1997), which led to the desiccation of
most of the springs in the Acacus (Cremaschi et al., 2010) and the
shrinkage of the level of interdune lakes in the ergs around it
(Zerboni and Cremaschi, 2012). A more detailed discussion of this
topic is presented in the following subsection.
The upper part of Unit IV, formed during the LA3 occupation of
the site, corresponds to an increase of the content of organic matter
content and can be correlated to the pollen zone TK-WS (sub zone
TK 1c) on the basis of pollen content. Pollen indicates a drier
environment compared to the lower stratigraphic Units and strong
seasonal variations characterized by a variety of habitats with
xerophilous plants alternating with grassland. LA3 foragers coped
with this variability through a series of changes in intrasite orga-
nization (see Biagetti and di Lernia, 2013), and resource exploita-
tion; for instance, new wild cereals, including millets with large
pollen grains, were collected. Besides a strong reduction in water
availability, residual freshwater bodies continued to provide food
and raw materials, which is evident from Typha transported inside
the rock shelter. The fairly rapid increase of Poaceae pollen in
spectra highlights the relevance of wild cereal exploitation:
intensively harvested, possibly in the late summer, they were
stored using both kettles and basketry containers (di Lernia et al.,
2012). Moreover, seed and fruit accumulations are common at the
site and, as reported by Olmi et al. (2011), sometimes they suggest
special selection.
Deposit properties and the pollen assemblage suggest an
important change in the formation processes of the sequence
throughout Units III, II and I (pollen zones 2 a, b, c), which accu-
mulated during the EP and MP periods and attest to a new increase
in water availability. These indicate a modification in the landscape
surrounding the Takarkori rock shelter with the spread of perma-
nent water bodies and the coexistence of different habitats. Xeric
environments were still present representing the echoes of the
previous arid spell. A cultural shift in plant exploitation is also
evident in the pollen record: Poaceae include many large pollen
grasses, which belong to the wild cereals harvested or browsed and
brought into the site. During this phase, human groups contributed
to the formation of the deposit with a larger input of plant organics
within the rock shelter. The significant increase in fine sediments
(clay þsilt) evident in this part of the sequence, in fact, can be
hardly explained by climatic-driven processes, such as wind ac-
tivity or in situ weathering of quartz grains. Instead, it was probably
promoted by an anthropogenic contribution to sedimentation by
means of the introduction of exotic grains during domestic
activities.
The upper part of Unit I, which was occupied during a second
phase of the MP period (pollen zone TK-NS: Tk2c; correlated to
TK-WS: Tkw3), records significant environmental instability in a
shift towards drier climatic conditions. A general increase of the
sandy fraction in the deposit, with sand grains displaying a
moderate sorting in thin section, and a reduction of the organic
content confirm this evidence. Moreover, the decrease in pollen
concentrations is due to low input of pollen in sediments. This
mirrors the spread of low pollen-producing plants such as acacias
and other entomophilous species, and the decrease of high-
producing plants such as grasses. Though some freshwater habi-
tats were still present, increasing aridity pushed the expansion of
the dry savannah.
Inside the rock shelter the final transition to arid conditions is
indicated by well preserved layers of ovicaprine dung and sand-
stone blocks collapsed from its vault. The latter acted as protection
for the stratigraphic sequence by later enhanced wind erosion. The
collapse of the vault (and the protection of cave sediments from
erosion) is a widespread MiddleeLate Holocene phenomenon in
the Tadrart Acacus region (Cremaschi, 1998; Cremaschi and
Zerboni, 2011) and was related to slope instability under progres-
sively more arid environmental conditions. Outside the rock shel-
ter, where the surface was exposed to residual rainfall, a complex
pedogenetic evolution of the sequence occurred. From the begin-
ning of drier conditions, this included the formation of an argillic
laminar horizon at the topsoil, the formation of a desert pavement,
and the deposition (between c. 5500 and 4000 cal yr BP) of Mn-rich
rock varnish on the outcropping part of rocks and stones lying on
the topographic surface (Cremaschi, 1996; Zerboni, 2008).
6.3.2. Local and regional palaeoenvironmental correlations
The palaeoenvironmental record inferred from the stratigraphic
sequence at Takarkori reflects local modifications in environmental
settings and changes in the availability of natural resources.
Moreover, data from this site can be compared with other regional
and continental archives for proxy data, confirming the global
importance of anthropogenic sequences within rock shelters in arid
lands. A general assessment of the palaeoclimatic significance of
M. Cremaschi et al. / Quaternary Science Reviews 101 (2014) 36e60 55
this case study is given by correlating it with data from other
Saharan and African localities (Fig. 16).
Firstly, new evidence from Takarkori can be compared and
validated with other palaeobotanical and palaeohydrological re-
cords available for the Tadrart Acacus and the Libyan central Sahara.
Data from Takarkori illustrate that the first occupation of the site
(LA phase, 10,170e8180 cal yr BP) was characterized by a contin-
uous plant cover and possibly ample water availability; these ob-
servations well fit with palaeohydrological data from the Tadrart
Acacus and the surrounding lowlands, which confirm a general
recharge of surface aquifers after the increase in monsoonal rainfall
supply. This event, consistently dated across the entire region of
North Africa (e.g., Damnati, 2000; Gasse, 2000; Nicoll, 2004;
Zerboni, 2013), occurred since the beginning of the Holocene.
Radiocarbon chronology of interdune lake basins in the erg Uan
Kasa (c. 50 km off the eastern fringe of the Tadrart Acacus) and
edeyen of Murzuq (c. 200 km E of the Tadrart Acacus) indicates the
outcrop of the water table at c. 10,450e9500 cal yr BP (Cremaschi,
1998, 2002; Zerboni, 2006; Cremaschi and Zerboni, 2009; Zerboni
and Cremaschi, 2012). The activation of springs within the Tadrart
Acacus massif is recorded in the same phase, indicated by the
deposition of calcareous tufa since c. 9500 cal yr BP (Cremaschi
et al., 2010), and the activation of the main river systems (Pachur,
1980; Perego et al., 2007; Cremaschi and Zerboni, 2011). A num-
ber of other proxy data confirm a general increase of water avail-
ability along the first two millennia of the Holocene (Cremaschi,
1998, 2002); moreover, during this phase the region is systemati-
cally exploited by hunteregatherers groups (di Lernia, 1999;
Cancellieri and di Lernia, 2014) and pollen spectra from the Wadi
Teshuinat region (central Tadrart Acacus) indicate a wide distri-
bution of grasslands with Poaceae and Cyperaceae (Mercuri,
2008b;Fig. 16).
At a continental scale, the increase in water availability in the
Libyan central Sahara is in agreement with the onset of the AHP,
controlled by the migration of the ITCZ, which penetrated about
500e800 km north of its present position (e.g., Petit-Maire et al.,
1995; Gasse, 2000; Maley and Vernet, 2013), thanks to the expan-
sion of the SW African Monsoon domain. It is widely accepted that
the strengthening of the African Monsoon was primarily controlled
by an insolation maximum (Berger and Loutre, 1991; Rossignol-
Strick, 1999; Gasse, 2000; deMenocal et al., 2000; Garcin et al.,
2007). In this phase the recharge of the North African deep aquifers
began (Zuppi and Sacchi, 2004) and the Saharan drainage systems
became active (Pachur,1980; Williams and Adamson, 1980; Becker
and Fürst, 1991), contributing to the discharge of freshwater into
the Mediterranean Sea and allowing the deposition of the organic-
rich sapropel S1 (Ariztegui et al., 2000; Rohling et al., 2002).
Moreover, the Sahara and Sahel saw a consistent phase of lake ac-
tivities: increased monsoonal activity contributed to high stands of
the main lake basins (e.g., Gasse, 1977, 2000; Servant and Servant-
Vildary, 1980; Maley, 2004; Shanahan et al., 2006; Marshall et al.,
2011), while a number of piezometric ponds came to light from
Sudan to Mali (e.g., Pachur and Hoelzmann, 1991; Ritchie, 1994;
Hoelzmann et al., 2001, 2010; Kuper and Kr€
opelin, 2006;
Williams, 2009; Hassan et al., 2012).
According to pollen data and the degree of organic preservation,
the subsequent phases of LA occupation of the rock shelter (LA2 and
LA3) occurred under progressively more arid environmental con-
ditions, which led to a marginalization of freshwater environments.
In the Tadrart Acacus, for almost the same period, stable isotope (C
and O) values from calcareous tufa suggest a substantial reduction of
precipitation (Cremaschi et al., 2010), signalling a more consistent
drought event, which in the region is well attested by a generalized
shrinking of interdune lakes level and interruption of spring activity
(Zerboni and Cremaschi, 2012). Also, the pollen record from the
Teshuinat area highlights a decrease in water availability thanks to a
rapid expansion of desert taxa (Mercuri, 2008b). Palaeohydrological
data indicate that the conditions suitable for the outcrop of the
water table were substantially reduced around 8200 cal yr BP,
largely coincident with the well-known event recorded at 8.2 ka BP
(Alley et al.,1997; Barber et al.,1999; Mayewski et al., 2004; Kobashi
et al., 2007; Thomas et al., 2007). The identification of the envi-
ronmental effects of a rapid climate change, as in the Saharan region
the 8.2 ka BP event, is still matter of discussion, as in most of the
studied localities the palaeoclimatic signature of this phase is poorly
or not preserved and many dating uncertainties still exist (Zerboni,
2013). But the attribution of the Early Holocene dry phase inter-
rupting the AHP, leading to a shutdown of the monsoonal water
supply is, for instance, attested by a palaeoclimatic model (Wiersma
and Renssen, 2006) supported by independent field data. This
confirms the strong influence of an abrupt drainage of ice-dammed
lakes in North America on the circulation in the Atlantic Ocean; its
main effect was a significant reduction in sea-surface temperature in
the northern and tropical Atlantic, resulting in a temperature
reduction in the Guinea Gulf, strong decrease in evaporation and
decreased strength of the SW African monsoon. Furthermore, a
general reduction in the intensity of the SW African monsoon in the
northern Sahel and in the Sahara was observed in records from
freshwater ecosystems at several localities. This dry interval was
reported from sites including Lake Tigalmamine (Lamb et al., 1995),
Sebkha Mellala (Gasse et al., 1990), Tin Ouaffadene depression
(Gasse, 2000), Bahr El-Ghazal depression (Servant and Servant-
Vildary, 1980), Lake Bosumtwi (Talbot et al., 1984), Lake Abh
e
(Gasse, 1977), Lake Tanganyika, and Lake Malawi (Gasse, 2000).
Some African summer monsoon-fed lakes also show a reduction in
the intensity and penetration of the African Monsoon between c.
8500 and 7800 cal yr BP (Gasse and Van Campo, 1994; Gasse, 2000).
The occurrence of a dry period during the AHP is evident also in the
eastern African monsoon domain, where a high aerosol content of
the Kilimanjaro ice core, associated with rapid fluctuations of lake
levels (Thompson et al., 2002), and a major arid phase in the Tigray
region are registered (Dramis et al., 2003). Apart from this inter-
pretation of published data, the most significant identification of the
8.2 ka BP event in the Saharan region is from lake Gureinat, in
western Nubia. This lacustrine sequence was found in a basin iso-
lated from large-scale artesian systems and thus it preserves hy-
drological changes resulting from any modification in local rainfall
(Hoelzmann et al., 2010). This long-term lake trend was interrupted
by a shorter-lived regression event at 8.2/7.6 cal ka BP, which
possibly led to complete lake desiccation.
It is noteworthy that at the Takarkori rock shelter this climatic
event is not recorded by any change in the sedimentary sequence,
which is continuous and dominated by anthropogenic input.
However, the climatic change is clearly seen in the pollen assem-
blage, which in this period indicates an increase of desert taxa and
decreased environmental humidity. The effects of drought at
around 8.2/7.6 cal ka BP were much more effective in the lowlands
surrounding the massifs, where the interdune lakes dried out
completely (Cremaschi and Zerboni, 2011; Zerboni and Cremaschi,
2012), than inside the mountain system, where residual water
persisted in the phreatic network (Cremaschi et al., 2010). Water
availability gave human communities the opportunity to overcome
the drought by settling the highest reach of the Tadrart Acacus
massif. This may explain why the anthropogenic contribution to the
sedimentation of the Takarkori rock shelter was not interrupted. It
must also be emphasized that, as discussed elsewhere (di Lernia,
2013), the 8.2 ka BP dry event seems also to correspond in the
archaeological record of the Tadrart Acacus to a main transition
from the last hunteregatherer activity to the first introduction of
domestic cattle by Early Pastoral Neolithic groups.
M. Cremaschi et al. / Quaternary Science Reviews 101 (2014) 36e6056
In the Takarkori sequence, the second part of AHP (Pastoral
phases, Units III, II, and I) is marked by a greater input of plant re-
mains and the pollen assemblage reflects an expansion of fresh-
water conditions in the surroundings, with several patches of xeric
environments. Finally, the upper part of Unit I indicates a climatic
transition towards a more unsteady climate, with marked season-
ality and aridity increasing progressively. The harshening phase
culminates at the end of the occupation of the site, when the onset
of desert environmental conditions led to the collapse of the roof of
the rock shelter and the formation of rock varnish. Also in the
Teshuinat region, the pollen record encompassing the Pastoral
period suggests the restoration of wetter environmental conditions
at its beginning, followed after the Middle Holocene by a progres-
sive increase of taxa belonging to desert communities (Mercuri,
2008b). Between the dunes, the water table cropped out again
but sedimentological and palaeontological data from lake sedi-
ments indicate an enhanced seasonality, which was characterized
by monsoonal precipitations in summer and winter season marked
by the drop (or at least the desiccation) of lake basins (Zerboni,
2006; Cremaschi and Zerboni, 2011; Zerboni and Cremaschi,
2012). These processes are a local expression, together with the
tree-ring record of Cupressus dupreziana (Cremaschi et al., 2006), of
the general environmental instability that occurred in the central
Sahara since the Middle Holocene transition (Cremaschi, 1998;
Mercuri, 2008a,b; Cremaschi and Zerboni, 2009, 2011; di Lernia
et al., 2013). In many parts of North Africa the Middle Holocene is
characterized by a change in the environment, announcing the
gradual decline of monsoon rainfall tuned by the modifications of
the orbital forcing (weakening of incoming insolation) and the
termination of the AHP (e.g., Gasse, 2000; Mayewski et al., 2004;
Nicoll, 2004). Even if the withdrawal of the monsoon systems
was regulated by an orbital change in summer insolation, the steps
toward aridity appear to have been shaped by local hydrological
and geomorphological conditions, and at some locations, water
availability was reduced more rapidly than elsewhere. Freshwater
ecosystems responded to drought differently, mostly on the basis of
the size of their hydrological reservoir (Kr€
opelin et al., 2008;
Cremaschi and Zerboni, 2009; L
ezine, 2009). Vegetation dimin-
ished and the savannah environment was disappearing in the
Middle Holocene, whereas desert species substituted more water-
dependent plant taxa (Neumann, 1989). The onset of aridity is
recorded in lakes from many localities between 6 and 5 cal ka BP,
and isotopic data indicate a progressive decrease in the precipita-
tion/evaporation balance, confirming a transition towards desert
environmental conditions (Abell and Hoelzmann, 2000;
Hoelzmann et al., 2001; Nicoll, 2004; Zerboni, 2013).
7. Conclusions
The deposit of the Takarkori rock shelter may be regarded
mainly as anthropogenic and testifies to an almost continuous
human occupation since the onset of the AHP up to its termination,
which corresponded with the Middle Holocene transition (Roberts
et al., 2011a). While the pollen content highlights a reduction of
water availability in the region at c. 8200 cal yr BP, archaeological,
chronometric, and sedimentary characteristics of the sequence
exclude any interruption in the human frequentation, even during
the dry period. This is interpreted as being attributable to a possible
persistence of water resources inside the central Saharan massifs, in
contrast with surrounding lowlands that dried out completely. As a
consequence these areas acted as a refuge for human groups, which
in the same period modified their subsistence strategies, also
exploiting domesticated animals. A wet Middle Holocene phase is
attested both by sediments and pollen spectra, corresponding to an
intensified use of the rock shelter and to an increased accumulation
therein of grass, including wild cereals. Climate deterioration at the
end of the AHP period began to influence the vegetal cover, pro-
moting the spread of dry species from the base of Unit I. At this
period the site was occupied only seasonally by Late Pastoral
groups, namely during the winter season. The sedimentary record
of this period inside the rock shelter is affected by erosion and
mostly preserved by collapsed blocks from the vault. However, the
contemporary horizons of the western sequence outside the shelter
point to the complexity of the processes conducive to the onset of
dominant dry conditions in the area.
The stratigraphic sequence of Takarkori is representative of the
high potential for palaeoclimatic investigation of the central
Saharan rock shelter deposits, which have preserved the organic
matter accumulated in the EarlyeMid-Holocene due to a long-
lasting occupation. The potential of this kind of sediments as
proxy data for environmental changes is not only local, but global,
as it was influenced by both long and short-term fluctuations of
Earth's climate.
Acknowledgements
The research has been carried out under the aegis of the Italian-
Libyan Archaeological Mission in the Acacus and Messak, Sapienza
University of Rome and Department of Archaeology, Tripoli,
directed by Savino di Lernia. Main funds come from Sapienza
Universit
a di Roma through Grandi Scavi di Ateneo and Italian
Ministry of Foreign Affairs (DGSP), from 2003 to 2011 entrusted to
SDL, together with additional funds coming from Italian Ministry of
University and Research, entrusted to MC, AMM, and SdL. All
necessary permits were obtained for the field studies and labora-
tory analyses (including destructive processes) presented here. SdL
designed the research and directed the fieldwork, providing the
chronological and archaeological framework. MC and AZ per-
formed geomorphological and micromophological analysis. AMM
and LO performed pollen analysis. SB contributed to the analysis of
the stratigraphy and archaeological. Our warmest thanks to the
excavation staff: R. Castelli (also for taking part to the survey of the
area), L. Cavorsi, E. Cancellieri, F. Del Fattore, T. Latini, M. Massussi, F.
Merighi, A. Monaco, C. Pizzi, G. Poggi, F. Ricci, and M. Tarantini. We
are indebted with M. Gallinaro for her advice, assistance and help.
Many thanks to S. Giovannetti for her help in the field and lab. We
wish to thank all the colleagues of the Libyan Department of
Archaeology for their help and support: in Tripoli A. Khaddouri, G.
Anag, S. Agab, M. Turjman, A. Jamali, B. Galgam. A special thought to
the late E. Azzebi, co-director of the project before his sudden and
premature death. Many thanks to N. Bergamaschi and E. Ferrari for
helping with sedimentological analyses. E. Modrall is kindly
acknowledged for the skilful revision of English language. We wish
to thank the people in Ghat, in particular M. Denda and B. Baba; the
several workers who helped during excavation; the people and staff
at Dar Sahara Co., that provided logistics and camp: S. Scarpa, A.
Ravenna, Dawd, Malik, Bilad, Ameneknek, and Hassan. We are
grateful to CO.NI.COS. staff, in particular A. Becchio, A. Bottero and F.
Castigliola for their support and hospitality in Tripoli and Tahala.
Appendix A. Supplementary data
Supplementary data related to this article can be found at http://
dx.doi.org/10.1016/j.quascirev.2014.07.004.
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