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Field photo at the north face of the Chippewa Bay road cut. White Potsdam Sandstone below, and bioturbated, gray sandstone of Theresa Formation above.
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ABSTRACT--The Cambrian-Ordovician Potsdam Sandstone, Theresa Formation, and Canadian correlatives in the St. Lawrence Lowlands preserve tide-dominate facies during the basal Cambrian
transgression. Low intertidal sand flats in the upper Potsdam
contain a Skolithos Ichnofacies dominated by Diplocraterion
parallelum in clean, herringbone cross-bedded...
Citations
... Nikolaisen & Henningsmoen (1990) Here we provide new information on trace fossils from the Upper Member of the Duolbagáisá Formation, based on two slabs with well-preserved trace fossils. Remarkable are numerous specimens of Halimedides, an ichnogenus A c c e p t e d m a n u s c r i p t 5 consisting of strings with ring-like swellings, with the only previous Cambrian record consisting of single specimens from Sweden and eastern USA (Bjerstedt & Erickson, 1989;Jensen, 1997). These slabs also provide new records of the rare Bergaueria sucta. ...
... There is a moderately rich Ordovician record of Halimedides, whereas that of the Cambrian is poor (Table 1). Prior to the material reported here, the Cambrian record consisted of a single specimen reported by Jensen (1997) from the File Haidar Formation (Mickwitzia Sandstone Member; Cambrian Stage 3 or 4, see Nielsen & Schovsbo, 2011, and a short fragment reported as a possible Fustiglyphus by Bjerstedt & Erickson (1989) fig. 17D) also may be more closely comparable to Protovirgularia or Halimedides, rather than the dumb-bell shaped Arthraria. ...
New information is provided on trace fossils from the Cambrian Series 2 to Miaolingian in the Upper Member of the Duolbagáisá Formation of northern Norway. This includes the first rich Cambrian material of Halimedides, a trace fossil with more or less regularly spaced swellings of different shapes connected
by a median string. It is known principally from Mesozoic and younger deep-sea deposits, with a scarce Paleozoic record, making this one of the oldest occurrences of this ichnogenus. Other trace fossils occurring with Halimedides include the rare Bergaueria sucta, Palaeophycus imbricatus and Cruziana tenella. Psammichnites gigas and Syringomorpha nilssoni are documented photographically for the first time from this unit. The trace fossil association shows general similarity with that of the slightly
older Mickwitzia Sandstone Member of southern Sweden and suggests a broad distribution of late early Cambrian trace-fossil producers across Baltica.
... Nikolaisen & Henningsmoen (1990) Here we provide new information on trace fossils from the Upper Member of the Duolbagáisá Formation, based on two slabs with well-preserved trace fossils. Remarkable are numerous specimens of Halimedides, an ichnogenus A c c e p t e d m a n u s c r i p t 5 consisting of strings with ring-like swellings, with the only previous Cambrian record consisting of single specimens from Sweden and eastern USA (Bjerstedt & Erickson, 1989;Jensen, 1997). These slabs also provide new records of the rare Bergaueria sucta. ...
... There is a moderately rich Ordovician record of Halimedides, whereas that of the Cambrian is poor (Table 1). Prior to the material reported here, the Cambrian record consisted of a single specimen reported by Jensen (1997) from the File Haidar Formation (Mickwitzia Sandstone Member; Cambrian Stage 3 or 4, see Nielsen & Schovsbo, 2011, and a short fragment reported as a possible Fustiglyphus by Bjerstedt & Erickson (1989) fig. 17D) also may be more closely comparable to Protovirgularia or Halimedides, rather than the dumb-bell shaped Arthraria. ...
New information is provided on trace fossils from the Cambrian Series 2 to Miaolingian in the Upper Member of the Duolbagáisá Formation of northern Norway. This includes the first rich Cambrian material of Halimedides, a trace fossil with more or less regularly spaced swellings of different shapes connected by a median string. It is known principally from Mesozoic and younger deep-sea deposits, with a scarce Paleozoic record, making this one of the oldest occurrences of this ichnogenus. Other trace fossils occurring with Halimedides include the rare Bergaueria sucta, Palaeophycus imbricatus and Cruziana tenella. Psammichnites gigas and Syringomorpha nilssoni are documented photographically for the first time from this unit. The trace fossil association shows general similarity with that of the slightly older Mickwitzia Sandstone Member of southern Sweden and suggests a broad distribution of late early Cambrian trace-fossil producers across Baltica.
... Diplocraterion is generally interpreted as a dwelling (domichnial) burrow of an animal formed in a high energy environment (Fürsich, 1974;Fillion and Pickerill, 1990;Schlirf, 2000). There are numerous reports from sediments interpreted as of tidal origin (Bjerstedt and Erickson, 1989), and several studies focused on the ecological and sedimentological implications of Diplocraterion (Goldring, 1962;Fürsich, 1974;Bjerstedt and Erickson, 1989). Bromley and Hanken (1991) have described Diplocraterion parallelum from the lower Cambrian. ...
... Diplocraterion is generally interpreted as a dwelling (domichnial) burrow of an animal formed in a high energy environment (Fürsich, 1974;Fillion and Pickerill, 1990;Schlirf, 2000). There are numerous reports from sediments interpreted as of tidal origin (Bjerstedt and Erickson, 1989), and several studies focused on the ecological and sedimentological implications of Diplocraterion (Goldring, 1962;Fürsich, 1974;Bjerstedt and Erickson, 1989). Bromley and Hanken (1991) have described Diplocraterion parallelum from the lower Cambrian. ...
The Faïdja Formation displays mixed siliciclastic-carbonate deposits distributed in three members, which are organised from bottom to top as follows: the Clayey Sandstone Faïdja Member; the Clayey Limestone Bel Aoura Member and the Sandy Claystone Douaouda Member. Sedimentological data indicate the evolution of a subsiding marine environment from the shelf edge to the lower shoreface, sporadically dominated by storms. New age based on recently collected ammonite fauna allowed us to update the age of the Faïdja Formation as Early-Late Kimmeridgian. Ichnological analysis reveals the occurrence of abundant and diverse invertebrate trace fossils, grouped in four ichnoassociations. Ichnoassociation -A- coincides with the lowermost part of the Clayey Sandstone Faïdja Member; it is distinguished by a combination of pre-graphoglyptids and post-depositional traces, ascribed to the distal Cruziana ichnofacies transitional to the Nereites ichnofacies, which indicates a lower offshore zone to shelf edge environment characterised by a low-oxygenated period (anoxic event), frequent storm events and nutrient frequency. Ichnoassociation -B- occupies the middle and upper parts of the Clayey Sandstone Faïdja Member, it is characterised by an abundance of post-depositional traces, corresponding to the archetypal Cruziana ichnofacies that indicates a lower to transitional offshore environment with short phases of low hydrodynamic energy. Ichnoassociation -C- corresponds to the Clayey Limestone Bel Aoura Member that coincides with a drastic facial change and depositional conditions; this association documents a proximal Cruziana ichnofacies, and indicates an upper to transitional offshore zone as a depositional environment. Finally, ichnoassociation -D- coincides with the Sandy Claystone Douaouda Member; it is ascribed to the proximal Cruziana ichnofacies, indicating a lower shoreface environment. The combined sedimentological and ichnological data indicates a relatively subsiding platform with shallowing upwards corresponding to distal, archetypal and proximal Cruziana ichnofacies, respectively.
... The massive bedding of this float block is ambiguous. Fustiglyphus burrows are certainly almost invariably reported as being parallel to bedding (examples include Osgood 1970 [as Rhabdoglyphus sp.]; Bjerstedt and Erickson 1989;Stanley and Pickerill 1993;Jensen 1997;Buatois et al. 2001;Zonneveld et al. 2010). Yet Miller and Rehmer (1982, p. 891), while noting this trace on the base of the Carlisle Center Member (Lower Devonian, New York State), also recorded that 'Animals making this trace moved above and/ or below as well as along the interface.' ...
The top of the Whitby Mudstone Formation (Lias Group, Toarcian, Bifrons ammonite Zone) is exposed low in the geological Site of Special Scientific Interest at Ketton Quarry, East Midlands. A rare burrow of Fustiglyphus annulatus Vialov from this part of the succession, not reported from the Whitby Mudstone Formation hitherto, was collected from float. In the dull brown mudrock, the burrow has a contrasting fill of grey sandstone. The shaft of the burrow is cylindrical, with two broad, bell-shaped chambers. Fustiglyphus annulatus is found in deeper water deposits in the post-Palaeozoic, so its occurrence in the Whitby Mudstone Formation, an offshore shelf deposit, is not unexpected. However, orientation is equivocal; the burrow was either angled at 45° to bedding, based on the evidence of an associated Arenicolites isp., or parallel to bedding, its common configuration.
... The Skolithos ichnofacies has been found in many localities around the world, within various depositional environments such as estuary mouth (Hiscott et al. 1984;Mángano et al. 1996), shoreface shelf (Hallam & Swett 1966;McKie 1990;Prave 1991;Simpson et al. 2002;McIlroy & Garton 2004;Davies et al. 2009) shorefaceintertidal zone (Simpson & Eriksson 1990;Simpson 1991) and intertidal-subtidal zone (Goodwin & Anderson 1974;Baldwin 1977;Driese et al. 1980;Cornish 1986;Bjerstedt & Erickson 1989). It occurred also in nonmarine environments (Fitzgerald & Barrett 1986). ...
Skolithos burrows indicate high-energy nearshore environment. In this paper, abundant Scolithos burrows from two particular levels of the Cambrian–Ordovician boundary interval of the Central Anti-Atlas, Morocco, are described for the first time. The first level occurs at the boundarybetween the Azlag Formation and Jbel Lmgaysmat Formation (Furongian), where the burrows are 5–80 cm long and 3–7 mm wide, straight to slightly curved, with mostly circular, but sometimes also oval apertures.The second level occurs within the unconformity underlining the Tremadocian cycle (Fezouata Shale). The burrows of Skolithos linearis associated with that level are straight to slightly curved, 2–15 cm long and 2–4 mm wide. The absence of encrustation above the burrowed beds indicates that these traces were made in a soft sediment.
... Furthermore, complex isopach and lithofacies distributions and the general lack of age-diagnostic fossils, ash beds, or easily correlated stratal surfaces in a compositionally monotonous, mostly continental siliciclastic succession have confounded dep- ositional age determinations and stratigraphic correlations. Dis- entangling the existing inconsistencies and complexities of Potsdam Group stratigraphy and lithofacies remains important for gaining a better understanding of the Early Paleozoic history of North America and also for providing context to studies of the paleoecology of Early Paleozoic microbial and metazoan life (Clark and Usher 1948;Bjerstedt and Erickson 1989;MacNaughton et al. 2002;Hagadorn and Belt 2008;Collette and Hagadorn 2010;Hagadorn et al. 2011). Furthermore, regional correlations between the Potsdam Group and Lower Paleozoic strata across eastern North America are uncertain, but are needed to better constrain the eustatic fluctuations, climate change events, and tectonic events that affected Early Paleozoic Laurentia (e.g., Landing et al. 2003Landing et al. , 2009Salad Hersi and Dix 2006;Lavoie 2008;Cherns et al. 2013;Lowe and Arnott 2016). ...
... In this work, the Potsdam comprises three formations, which stratigraphically upward are Ausable, Hannawa Falls, and Keeseville ( Fig. 3; Table 3). It has long been understood that units of the Potsdam Group in Canada (Covey Hill, Nepean, and Cairnside for- mations) are equivalent to the units in New York State (e.g., Wilson 1946;Kirwan 1963;Otvos 1966;Lewis 1971;Brand and Rust 1977;Bjerstedt and Erickson 1989;Sanford 2007;Landing et al. 2009;Hagadorn et al. 2011;Lowe and Arnott 2016), and this work supports that. Therefore, the names of units from Canada are here abandoned and replaced everywhere by the names of equivalent units in New York State, which significantly predate the Canadian formation names (originally from Emmons (1841) and Alling (1919)). ...
... [Colour online.] the Keeseville Formation crop out along Highway 12 in northern New York State, between Alexandria Bay and Blind Bay (e.g., sec- tions 86, 87, 100, 104, 112; Fig. 16D). Together these closely spaced outcrops should be considered a composite stratotype of the Keeseville Formation, as they expose the entire Keeseville Forma- tion in this area, most of its constituent lithofacies, and its lower and upper contacts (Selleck 1975(Selleck , 1978b(Selleck , 1993Bjerstedt and Erickson 1989;Lowe 2014). Throughout much of the Ottawa Em- bayment and Quebec Basin, the Keeseville Formation is subdi- vided into the upper Keeseville Formation and upper Keeseville Formation that in most places is separated by an unconformity (Figs. 3, 17). ...
The Potsdam Group is a Cambrian to Lower Ordovician siliciclastic unit that crops out along the southeastern margins of the Ottawa graben. From its base upward, the Potsdam consists of the Ausable, Hannawa Falls, and Keeseville formations. In addition, the Potsdam is subdivided into three allounits: allounit 1 comprises the Ausable and Hannawa Falls, and allounits 2 and 3, respectively, the lower and upper parts of the Keeseville. Allounit 1 records Early to Middle Cambrian syn-rift arkosic fluvial sedimentation (Ausable Formation) with interfingering mudstone, arkose, and dolostone of the marine Altona Member recording transgression of the easternmost part of the Ottawa graben. Rift sedimentation was followed by a Middle Cambrian climate change resulting in local quartzose aeolian sedimentation (Hannawa Falls Formation). Allounit 1 sedimentation termination coincided with latest(?) Middle Cambrian tectonic reactivation of parts of the Ottawa graben. Allounit 2 (lower Keeseville) records mainly Upper Cambrian quartzose fluvial sedimentation, with transgression of the northern Ottawa graben resulting in deposition of mixed carbonate–siliciclastic strata of the marine Riviere Aux Outardes Member. Sedimentation was then terminated by an earliest Ordovician regression and unconformity development. Allounit 3 (upper Keeseville) records diachronous transgression across the Ottawa graben that by the Arenigian culminated in mixed carbonate–siliciclastic, shallow marine sedimentation (Theresa Formation). The contact separating the Potsdam Group and Theresa Formation is conformable, except locally in parts of the northern Ottawa graben where the presence of localized islands and (or) coastal salients resulted in subaerial exposure and erosion of the uppermost Potsdam strata, and accordingly unconformity development.
... At Sapteshwar, the lithofacies is overlain by HSS lithofacies indicating repetition of backshore, marginal marine to marine conditions and fluctuations in sea level. Howard (1972), McCarthy (1979), Gaillard and Racheboeuf (2006), Bjerstedt and Erickson (1989), Bjerstedt (1987), Droser (1991), Kamola (1984), and Curran and White (1991) have described trace fossils as criteria for recognising shorelines-shoreface-foreshore and identical environment with sedimentary structures and lateral and vertical variation in the sedimentary sequence. ...
Himmatnagar Sandstone (lower to middle Cretaceous) is exposed in between Sabarmati River in the west to Vantada in the east around Himmatnagar Town in north Gujarat, India. The sequence is divisible in two members: The lower member is 65 m thick, mostly massive, horizontally stratified to hummocky stratified with abundant plant and trace fossils in assorted shales and sandstones. The upper member is ~ 12 m thick, cross–stratified and medium to coarse grained–gritty to cobbly in nature. Six lithofacies have been identified in the sequence, viz. 1. grey wacke (GW), 2. silty–shale (SS), 3. cross–stratified sandstone (CS), 4. horizontally stratified sandstone (HSS), and 5. planar cross–stratified sandstone (PCS) in the lower member; and 6. gritty–cobbly cross–stratified sandstone (GCCS) in the upper member. The lower member consists of plant fossils which are poor to moderately preserved and transported. The silty–shale lithofacies contains plant fossils (Pagiophyllum, Brachyphyllum, Gleichenia, Araucarites, circinate vernation of ferns, Williamsonia flower, twigs, petrified wood, conifer and its cone, etc.), body fossil (insect wing) and trace fossils (Skolithos, Monocraterion, Psilonichnus, Thalassinoides, Chondrites, Planolites, Palaeophycus, Calycraterion, Circulichnus, Ophiomorpha, Phoebichnus, etc.). In the cross–stratified sandstone lithofacies, body fossils (mainly fragmented bivalves, plant fossils (Weichselia reticulata, Matonidium indicum, Ptilophyllum, cycadean frond and fossil wood) and trace fossils (Monocraterion, Chondrites, Calycraterion, Thalassinoides, Psilonichnus and Skolithos) are recognized. On the other hand, in horizontally stratified sandstone lithofacies plant fossils (Sphenopteris, Pagiophyllum, Gleichenia, Elactocladus, Brachyphyllum, ferns, petrified wood, etc.) and trace fossils (Skolithos, Ophiomorpha, Psilonichnus, Monocraterion, Arenicolites, Diplocraterion, Thalassinoides, Teichichnus, Palaeophycus, Planolites, etc.) are present. While, large crustacean and vertebrate burrows, Skolithos, Thalassinoides, Ophiomorpha, etc are found in planar cross–stratified sandstone lithofacies. The trace fossils belong to Psilonichnus, Skolithos and Cruziana ichnofacies as per Seilacher (1967). The member also contains wedge shape geometry of beds similar to tidal partings as well as ridge and runnel structures, low–angle to hummocky cross–stratification, herringbone structure and parting lineation. Here, north to northeast palaeo–current direction is indicated by cross–stratification in the member. All these features lead to the depositional environment, which seems to be foreshore–tidal flat to middle shoreface for the lower member of the sequence. The upper member is composed of trough cross–stratified sandstones showing prominently southwest to south palaeo–current direction with angular to sub–rounded pebbles and cobbles of underlying rocks and fossil wood with lower erosional contact and channel structures at places. Based on above characteristics, depositional environment of upper member can be interpreted from estuarine to fluvial.
... In the east, Potsdam Group rocks occur in the Quebec Basin, bounded by the Laurentian Arch to the north, Oka-Beauharnois Arch to the west, and Saguenay Arch in the east (Sanford and Arnott, 2010). This siliciclastic sequence unconformably overlies the Precambrian (Grenville) basement rocks (Bjerstedt and Erickson, 1989; MacNaughton et al., 2002 Hoffman, 1972; Wolf and Dalrymple, 1985), and the Ausable Formation in upper New York State (Fisher, 1968; Sandford and Arnott, 2010). These rocks were deposited in dominantly aeolian, fluvial, and prograding fluvial and deltaic marine environments (Sanford and Arnott, 2010). ...
... These rocks were deposited in dominantly aeolian, fluvial, and prograding fluvial and deltaic marine environments (Sanford and Arnott, 2010). In Ontario, the upper Potsdam Group is known as the Nepean Formation (Bjerstedt and Erickson, 1989; MacNaughton et al., 2002), in Quebec as the Cairnside Formation (Globensky, 1982), and in northern New York State as the Keeseville Formation (Fisher, 1968; Sandford and Arnott, 2010 ). These rocks were deposited in shallow marine and aeolian settings (Bjerstedt , 2010). ...
... The shallow marine and eolian settings of the upper Potsdam Group and their associated sedimentary structures, trace fossils, and fossils are of specific interest to this study. Common sedimentary structures in the upper Potsdam include ripples, subaerial exposure features, and cross-bedding (Bjerstedt and Erickson, 1989). At nearby Ausable Chasm, New York, the rocks are predominantly medium grained, well-sorted arenites in thin beds, with occasional fine and coarse-grained layers (Hagadorn and Belt, 2008 ). ...
A large bedding-plane exposure of Late Cambrian age sandstone (upper Potsdam Group, Cairnside Formation) near Beauharnois Quebec permits detailed examination of the sediments and organisms that existed at the interface of sea and land in the earliest Paleozoic. These rocks show sedimentary structures and trace fossils indicative of supratidal, intertidal, and shallow-marine lithofacies. Palimpsest, planed-off and symmetrical ripples, halite casts, gas escape structures, polygonal structures and trough cross-stratification, along with trace fossils of Diplichnites, and Phycodes, are present. Track rows of the ichnogenus Diplichnites were documented in subaerially deposited fine-grained sandstone in close association with halite molds and polygonal structures, lending support to the hypothesis that these were among the first organisms to journey periodically onto land. This must have been an intertidal setting, as generation of halite casts required periodic flooding.
... An unconformity, in places angular, separates the Ausable Formation from the overlying Upper Cambrian-Lower Ordovician Keeseville Formation (Clark 1966;Sanford and Arnott 2010). The Keeseville Formation consists of quartz arenites and minor conglomerate of fluvial, eolian, marginal marine, and shallow marine origin (Selleck 1978;Bjerstedt and Erickson 1989;Sanford and Arnott 2010). The contact between the Potsdam Group and overlying Theresa Formation is defined by a change from marine siliciclastic to mixed siliciclastic-carbonate strata associated with the epeiric Sauk transgression. ...
... Previous studies of the Potsdam Group suggest that basement topography including bedrock ridges, localized knolls, hills, and cliffs, were present along the southwestern Ottawa Embayment during Potsdam sedimentation (Lewis 1963;Kirwan 1963;Otvos 1966;Wolf and Dalrymple 1984;Bjerstedt and Erickson 1989;Sanford and Arnott 2010). In contrast, farther east along the eastern Ottawa Embayment and into the Quebec Basin, sediments were deposited on a relatively open and flat alluvial plain (Fig. 2). ...
Two fluvial facies associations, braided and ephemeral fluvial, are recognized in strata of the Cambrian- Ordovician Potsdam Group in the Ottawa Embayment and Quebec Basin in northeastern North America. Braided fluvial sedimentation was dominated by the migration of coarse-grained sandy dunes and rare unit bars and local gravels that built up low-relief 0.4-5-m-thick downstream-accreting compound bars in very wide and shallow braided channels. Rare meter-scale confluence scours, incision, and filling of decimeter-thick bypass channels, and thin (≤ 7 cm) overbank deposition also occurred. Ephemeral fluvial sedimentation was dominated by the progradation of lobate terminal splays, most of which were deflated and/or reworked into thin (10-95 cm) sheets by eolian processes during the long recurrence intervals between floods. These strata were locally incised by rare, 0.3-1.9-m-thick scour-filling high-energy supercritical bedform strata and decimeter-thick bypass channels. Both braided and ephemeral fluvial deposits consist of meter-scale stacked, high-order stratal units separated by horizontal, laterally extensive surfaces recording the recurring buildup, avulsion, and finally abandonment of channel belts. In braided fluvial strata of the Potsdam the dominance of thin (≤ 2 m) elongated compound bars with low-relief (≤ 58) bar margins and internal accretion surfaces (≤ 158) suggest that braided channels and in-channel compound bars expanded laterally with negligible increase in flow depth during periods of increased discharge in the absence of bankstabilizing vegetation, similar to other examples of the pre-vegetated "sheet-braided" style. However, in areas where bedrock topography inhibited the lateral expansion of channels, thicker compound braid bars (1.2-3.5 m) with higherrelief accretion surfaces (up to 358), like those observed in post-Silurian and modern systems, preferentially formed in relatively deep channels. Ephemeral fluvial deposits here are similar to ephemeral examples throughout geologic history in that they mostly comprise poorly confined sheet-like terminal splays that accumulated in topographic lows. However, compared to several post-Silurian examples, strata in the Potsdam exhibit considerably more eolian reworking of splays and preservation of supercritical-bedform strata, a manifestation of greater rates of surface-water infiltration due to a lack of sheltering by rooted plants and propensity for unconfined flooding. Finally, in the upper part of the Potsdam two regional ephemeral fluvial units are interstratified with two braided fluvial units, providing evidence for shifts in regional climate. The sharp, areally extensive surfaces that separate these fluvial systems are interpreted to approximate time lines, and therein provide a means for relative and absolute chronostratigraphic correlation. These changes are correlated with documented Late Cambrian to Earliest Ordovician global climate fluctuations, with semiarid conditions and related ephemeral fluvial systems corresponding to global cooling events at ca. 491 and 487 Ma.
... At Sapteshwar, the lithofacies is overlain by HSS lithofacies indicating repetition of backshore, marginal marine to marine conditions and fluctuations in sea level. Howard (1972), McCarthy (1979), Gaillard and Racheboeuf (2006), Bjerstedt and Erickson (1989), Bjerstedt (1987), Droser (1991), Kamola (1984), and Curran and White (1991) have described trace fossils as criteria for recognising shorelines-shoreface-foreshore and identical environment with sedimentary structures and lateral and vertical variation in the sedimentary sequence. ...
Himmatnagar Sandstone (lower to middle Cretaceous) is exposed in between Sabarmati River in the west to Vantada in the east around Himmatnagar Town in north Gujarat, India. The sequence is divisible in two members: The lower member is 65 m thick, mostly massive, horizontally stratified to hummocky stratified with abundant plant and trace fossils in assorted shales and sandstones. The upper member is ~ 12 m thick, cross–stratified and medium to coarse grained–gritty to cobbly in nature. Six lithofacies have been identified in the sequence, viz. 1. grey wacke (GW), 2. silty–shale (SS), 3. cross–stratified sandstone (CS), 4. horizontally stratified sandstone (HSS), and 5. planar cross–stratified sandstone (PCS) in the lower member; and 6. gritty–cobbly cross–stratified sandstone (GCCS) in the upper member.
The lower member consists of plant fossils which are poor to moderately preserved and transported. The silty–shale lithofacies contains plant fossils (Pagiophyllum, Brachyphyllum, Gleichenia, Araucarites, circinate vernation of ferns, Williamsonia flower, twigs, petrified wood, conifer and its cone, etc.), body fossil (insect wing) and trace fossils (Skolithos, Monocraterion, Psilonichnus, Thalassinoides, Chondrites, Planolites, Palaeophycus, Calycraterion, Circulichnus, Ophiomorpha, Phoebichnus, etc.). In the cross–stratified sandstone lithofacies, body fossils (mainly fragmented bivalves, plant fossils (Weichselia reticulata, Matonidium indicum, Ptilophyllum, cycadean frond and fossil wood) and trace fossils (Monocraterion, Chondrites, Calycraterion, Thalassinoides, Psilonichnus and Skolithos) are recognized. On the other hand in horizontally stratified sandstone lithofacies plant fossils (Sphenopteris, Pagiophyllum, Gleichenia, Elactocladus, Brachyphyllum, ferns, petrified wood, etc.) and trace fossils (Skolithos, Ophiomorpha, Psilonichnus, Monocraterion, Arenicolites, Diplocraterion, Thalassinoides, Teichichnus, Palaeophycus, Planolites, etc.) are present. While, large crustacean and vertebrate burrows, Skolithos, Thalassinoides, Ophiomorpha, etc are found in planar cross–stratified sandstone lithofacies. The trace fossils belong to Psilonichnus, Skolithos and Cruziana ichnofacies as per Seilacher (1967). The member also contains wedge shape geometry of beds similar to tidal partings as well as ridge and runnel structures, low–angle to hummocky cross–stratification, herringbone structure and parting lineation. Here, north to northeast palaeo–current direction is indicated by cross–stratification in the member. All these features lead to the depositional environment, which seems to be foreshore–tidal flat to middle shoreface for the lower member of the sequence.
The upper member is composed of trough cross–stratified sandstones showing prominently southwest to south palaeo–current direction with angular to sub–rounded pebbles and cobbles of underlying rocks and fossil wood with lower erosional contact and channel structures at places. Based on above characteristics, depositional environment of upper member can be interpreted from estuarine to fluvial.
