Joseph P. Smoot

United States Geological Survey | USGS

Introduction The narrow-leaved cattail wetland (Hopfensperger and Engelhardt 2007) known as Dyke Marsh formally became a land holding of George Washington Memorial Parkway (GWMP, a unit of the national park system) in 1959, along with a congressional directive to honor a newly-let 30-year commercial sand and gravel dredge-mining lease at the site (...

New data support a model of a volcanic rifted margin for eastern Laurentia and the breakup of the supercontinent Rodinia. Upper Neoproterozoic–lower Cambrian rocks of the Chilhowee Group in the Blue Ridge Province of eastern North America are subdivided into two facies assemblages separated by an unconformity. Historically, the rocks have been corr...

Dyke Marsh, a distal tidal marsh along the Potomac River estuary, is diminishing rapidly in areal extent. This study documents Dyke Marsh erosion rates from the early-1860s to the present during pre-mining, mining, and post-mining phases. From the late-1930s to the mid-1970s, Dyke Marsh and the adjacent shallow riverbottom were mined for gravel, re...

A synthesis of old and new paleoclimatic data from the Pyramid and Winnemucca lake basins indicates that, between 48.0 and 11.5·103 calibrated years BP (hereafter ka), the climate of the western Great Basin was, to a degree, linked with the climate of the North Atlantic. Paleomagnetic secular variation (PSV) records from Pyramid Lake core PLC08-1 w...

We document frequent, rapid, strong, millennial-scale paleovegetation shifts throughout the late Pleistocene, within a 100,000+ yr interval (~ 115–15 ka) of terrestrial sediments from the mid-Atlantic Region (MAR) of North America. High-resolution analyses of fossil pollen from one core locality revealed a continuously shifting sequence of thermall...

A sediment core taken from the western edge of the Bonneville Basin has provided high-resolution proxy records of relative lake-size change for the period 45.1–10.5 calendar ka (hereafter ka). Age control was provided by a paleomagnetic secular variation (PSV)-based age model for Blue Lake core BL04-4. Continuous records of δ¹⁸O and total inorganic...

Paleomagnetic-secular-variation (PSV)-based age models for sediment cores from Pyramid Lake in the Lahontan Basin and the Blue Lake marshes in the Bonneville Basin were used to construct sedimentologic, isotopic, and mineralogic proxies of lake-size variation for the two pluvial lake systems for the period 45-11 cal ka (hereafter ka). Both PSV reco...

Recent geomorphic, lithostratigraphic, palynologic and chronostratigraphic investigations of the mid-Atlantic region show that much of the modern landscape flanking the Chesapeake Bay and the Potomac River is developed on late Quaternary sediments. These deposits, dated by OSL and 14C, include transgressive marine and estuarine sediments deposited...

Bear Lake sediments were predominantly aragonite for most of the Holocene, reflecting a hydrologically closed lake fed by groundwater and small streams. During the late Pleistocene, the Bear River flowed into Bear Lake and the lake waters spilled back into the Bear River drainage. At that time, sediment deposition was dominated by siliciclastic sed...

Saline lakes (lakes with >5000 ppm dissolved solutes) are common throughout the arid regions of the world. Their distribution is controlled by tectonic setting and climate, and thus their deposits take on an importance beyond their size and abundance in the geological column. To exploit this aspect of saline lakes an understanding is needed of thei...

The Eocene Green River Formation is one of the largest non-marine carbonate deposits in the world. The Wilkins Peak Member, which is made up predominantly of ‘primary’ dolomite micrite, has been interpreted as a playa-lake complex. The following subenvironments are recognized: alluvial fans, fringing sandflat with broad, sheet-like basinward tongue...

A variety of sedimentological evidence was used to construct the lake-level history for Bear Lake, Utah and Idaho, for the past ∼25,000 years. Shorelines provide evidence of precise lake levels, but they are infrequently preserved and are poorly dated. For cored sediment similar to that in the modern lake, grain-size distributions provide estimates...

We have recovered a 17-m lacustrine sediment core (PLC08-1) from Pyramid Lake, Nevada, near the site of core PLC92-2 (Benson et al., 1997; QR-47). PLC08-1 can be correlated with the well-dated PLC92-2 core on the basis of three volcanic ashes and lithostratigraphic variability. Initial natural remanent magnetization (NRM) and magnetic susceptibilit...

The Wilkins Peak Member of the Green River Formation is a non-marine dolomitic deposit that formed in an arid, hydrologically closed basin. A transect from the margin to the centre of the Wilkins Peak basin was examined in outcrop exposures in the south-eastern corner of the basin and was supplemented with published core descriptions. The rocks wer...

Sediment grain-size data and other observations indicate that Holocene Bear Lake experienced large lake-level changes, and that on average the lake was about 20 m below the modern full-lake level. Bear Lake, in northeastern Utah and southern Idaho, lies in an active half graben at an elevation of about 1800 m, covers an area of 280 km2, and is 63 m...

Mono Lake sediments have recorded five major oscillations in the hydrologic balance between A.D. 1700 and 1941. These oscillations can be correlated with tree-ring-based oscillations in Sierra Nevada snowpack. Comparison of a tree-ring-based reconstruction of the Pacific Decadal Oscillation (PDO) index (D'Arrigo et al., 2001) with a coral-based rec...

The Mono Lake excursion (MLE) is an important time marker that has been found in lake and marine sediments across much of the Northern Hemisphere. Dating of this event at its type locality, the Mono Basin of California, has yielded controversial results with the most recent effort concluding that the MLE may actually be the Laschamp excursion (Eart...

An extensive network of diabase intrusions occurs in several of the largest Mesozoic basins of Eastern North America, including the Culpeper, Gettysburg, Newark, and Hartford basins. Within each, great dikes, inclined sheets, and lopoliths cut through the surrounding sandstones, siltstones, and conglomerates in ways that subdivide the regional subs...

Continuous, high-resolution δ18O records from cored sediments of Pyramid Lake, Nevada, indicate that oscillations in the hydrologic balance occurred, on average, about every 150 years (yr) during the past 7630 calendar years (cal yr). The records are not stationary; during the past 2740 yr, drought durations ranged from 20 to 100 yr and intervals b...

In 1872, a magnitude 7.5–7.7 earthquake vertically offset the Owens Valley fault by more than a meter. An eyewitness reported a large wave on the surface of Owens Lake, presumably initiated by the earthquake. Physical evidence of this event is found in cores and trenches from Owens Lake, including soft-sediment deformation and fault offsets. A grad...

At Owens Lake, California, paleomagnetic data document the Matuyama/Brunhes polarity boundary near the bottom of a 323-m core (OL-92) and display numerous directional fluctuations throughout the Brunhes chron. Many of the intervals of high directional dispersion were previously interpreted to record magnetic excursions. For the upper V120 m, these...

We constructed a radiometrically calibrated proxy record of Late Pleistocene and Holocene climate change exceeding 230,000yr duration, using pollen profiles from two cores taken through age-equivalent dry lakes—one core having greater age control (via 230Th alpha mass-spectrometry) and the other having greater stratigraphic completeness. The better...

The chemistry of the carbonate-free clay-size fraction of Owens Lake sediments supports the use of total organic carbon and magnetic susceptibility as indicators of stadial–interstadial oscillations. Owens Lake records of total organic carbon, magnetic susceptibility, and chemical composition of the carbonate-free, clay-size fraction indicate that...

Oxygen-18 (18O) values of sediment from the Wilson Creek Formation, Mono Basin, California, indicate three scales of temporal variation (Dansgaard–Oeschger, Heinrich, and Milankovitch) in the hydrologic balance of Mono Lake between 35,400 and 12,90014C yr B.P. During this interval, Mono Lake experienced four lowstands each lasting from 1000 to 2000...

Uncalibrated radiocarbon data from core PLC92B taken from Wizards Cove in the Pyramid Lake subbasin indicate that the Trego Hot Springs and Wono tephra layers were deposited 23,200 ± 300 and 27,300 ± 30014C yr B.P. (uncorrected for reservoir effect). Sedimentological data from sites in the Pyramid Lake and Smoke Creek–Black Rock Desert subbasins in...

These crusts form by the complete evaporation of saline groundwater at the sediment-air interface. Efflorescent crusts also form where halite dust is introduced by wind, then dissolved by rain and reprecipitated as the rainwater is evaporated. Wind-blown silt and clay adhere to thin hydroscopic water films coating crystals in the efflorescent crust...

The Newark Basin Coring Project has recovered over 6730 m of continuous core from 7 coring sites. Cores spanning the 4800 m of Lockatong and Passic formations are characterized by cyclic lacustrine mudstone and shale, which reflect rise and fall of lake level in response to climatic fluctuations at intervals of 20 000 years and larger patterns of 1...

A new genus of Late Triassic palynomorph, Froelichsporites, is created and designated here for azonate, obligate tetrahedral spore tetrads which characteristically are found in Upper Triassic continental (fluvial, interfluvial, and lacustrine) strata of the Newark Supergroup of the eastern United States and Canada, the Dockum Group of Texas and New...

This chapter summarizes the sedimentary characteristics of non-marine environments. Non-marine evaporite deposits are common features of modern arid closed basins, but relatively few have been recognized in the geologic record. These evaporites are important because their depositional setting reflects both climatic and tectonic conditions and they...

The early Mesozoic Newark Supergroup consists of continental sedimentary rocks and basalt flows that occupy a NE-trending belt of elongate basins exposed in eastern North America. The basins were filled over a period of 30–40 m.y. spanning the Late Triassic to Early Jurassic, prior to the opening of the north Atlantic Ocean. The sedimentary rocks a...

In both coastal South Carolina and the New Madrid seismic zone, the earthquake-induced liquefaction features generally originated in clean sand deposits that contain no or few intercalated silt- or clay-rich strata. The local geologic setting is a major influence on both development and surface expression of sand blows. Major factors controlling sa...

Massive red or gray mudstones, which occur at the tops of 2- to 10-m-thick sedimentary cycles, constitute a large portion of the Newark Supergroup. The mudstones can be separated into four distinct types; each type can be related to a specific set of paleoenvironmental conditions through analogy to modern sedimentary environments. Mudcracked massiv...

Statabound base metals in the Newark Supergroup occur in fluvial sandstones and lacustrine mudstones. Copper minerals in the sandstones are associated with organic material or root structures within trough cross-beds with silty mudstone drapes. The sandstones are interpreted as deposits of meadering and possibly anastomosing rivers that had high su...

The Upper Triassic Lockatong Formation is composed of cycles of fine-grained sediments interpreted as lacustrine deposits. These sedimentary cycles were deposited in the Newark basin formed during rifting events associated with formation of the present-day Atlantic Ocean. Sedimentary cycles consist of laminated black shale, thin-bedded mudstones wi...

This is a non-marine dolomitic deposit. A transect from the margin to the centre of the Wilkins Peak basin was examined in outcrop exposures in the S - E corner of the basin and was supplemented with published core descriptions. The rocks were divided into seven facies based upon lithology, layering style and sedimentary fabrics. Five dolomitic fac...

The Wilkins Peak Member of the Green River Formation is a nonmarine, closed-basin, dolomitic carbonate deposit that intertongues with siliciclastic deposits at the basin edges. A transect from the basin margin to the basin center reveals six major subfacies. (1) The alluvial-fan subfacies is poorly sorted boulder conglomerates, cross-bedded gravels...

Thesis (Ph. D.)--Johns Hopkins University, (1978). Part II entitled: Origin of the carbonate sediments in the Wilkins Peak Member of the Lacustrine Green River Formation (Eocene) Wyoming, U.S.A. Includes bibliographical references. Photocopy.