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1.
The distribution of artifacts at the multi-component (Paleoindian through Middle Woodland) Munson Springs site (33Li251) is best explained by downward migration of objects through bioturbation processes rather than by a vertical sequence of occupation surfaces through a period of sediment accretion. At the noncultivated, 1800 m2, footslope site, the distribution of glacial diamict, loess, and drift- and bedrock-derived colluvium indicate widespread slope erosion during the late-glacial period with general backslope and footslope stability during the Holocene. Diagnostic Paleoindian artifacts were recovered from a BE soil horizon lying directly below fill material of a small (8 × 10 m) Early Woodland mound. Based on soil fine clay distribution, these artifacts lay about 30 cm below the premound land surface. Woodland artifacts are concentrated at depths of 10–20 cm immediately down slope from the mound. Soil horizonation and total and fine clay distributions within footslope profiles indicate no significant sediment accretion through the period of soil genesis and prehistoric site occupation. © 2001 John Wiley & Sons, Inc.  相似文献   

2.
Geoarchaeological investigations at the Clovis type site, Blackwater Locality No. 1, in 1983 and 1984 included core drilling, archaeological test excavations, stratigraphic profiling, sedimentary analyses, and radiocarbon dating. Six lines of core holes transverse to the outlet channel clearly defined the subsurface configuration and stratigraphy of the prehistoric spring run. Pieces of large animal bone from units B, C, D, and E that elsewhere in the site contain Paleoindian artifacts suggest occurrences of additional buried sites along the ancient spring run. Four Paleoindian projectile points recovered during archaeological testing confirm these prospects. The Clovis type site, located in an abandoned gravel pit, is in a natural depression initially occupied by a late Pleistocene lake. After breaching of the depression by overflow or sapping, it became a springhead and was enlarged by slumping and slopewash. Detailed stratigraphic profiling of the south wall of the abandoned gravel pit provided precise stratigraphic control for sediment sampling and radiocarbon dating, and revealed more complex microstratigraphy and facies relationships than heretofore known for the site. The interfingering of dune facies around the depression with lacustrine and spring-laid facies within it aid paleoclimatic interpretation. Deflational contacts within the depression appear to correlate with adjacent wedges of dune sand reflecting relatively arid intervals. Between these arid episodes occur intervals of increased ground water level attended initially by deposition of spring-laid sands of unit B during the late Pleistocene (13,000–11,500 yr B.P.). As the water table rose following a period of severe deflation, slumping and gravity flow deposited clayey sand, Unit C, on the floor of the blowout between 11,500 and 11,000 yr B.P. During this time Clovis people first appeared at the site. After another brief period of deflation, a lake rose causing sand of Unit D0 to be washed in from shore followed by deposition of diatomities, units D1 and D2. These were separated by a brief influx of eolian sand, unit D2z. Between 10,800 and 10,000 yr B.P. outflow from the lake was reduced by accumulation of eolian sand in the outlet while Folsom people and later Agate Basin people arrived to hunt bison during this time. Cody complex people appeared during and after a brief erosional episode that preceded deposition of eolian silt and sand of units E and F from 10,000 to 8000 yr B.P. Eolian deposition during post-Folsom time converted the pond to a wet meadow and eventually, during Cody time, to a grassy swale. Some of these deposits were blown out during the Altithermal arid period (ca. 8000-5000 yr B.P.), a time when prehistoric Archaic peoples excavated wells in the floor of the depression. Subsequent eolian activity has resulted in deflation and dune migration during the late Holocene. The best prospects for Paleoindian finds are along the buried outlet south of the south wall and in early Holocene dune sands on the uplands around the depression. © 1995 John Wiley & Sons, Inc.  相似文献   

3.
The Big Eddy site (23CE426) in the Sac River valley of southwest Missouri is a rare recorded example of distinctly stratified Early through Late Paleoindian cultural deposits. Early point types recovered from the site include Gainey, Sedgwick, Dalton (fluted and unfluted), San Patrice, Wilson, and Packard. The Paleoindian record at Big Eddy represents only a fraction of the site's prehistoric cultural record; stratified cultural deposits in alluvium above the Paleoindian components span the entire known prehistoric sequence, and terminal Pleistocene alluvium may contain pre‐Early Paleoindian cultural deposits. This study focused on the paleogeomorphic setting, stratigraphy, depositional environments, pedology, geochronology, and history of landscape evolution of the late Pleistocene and early Holocene alluvium at the site. The Paleoindian sequence is associated with a complex buried soil 2.85 m below the modern surface (T1a) of the first terrace of the Sac River valley in the site vicinity. This soil formed at the top of the early submember of the Rodgers Shelter Member (underlying the T1c paleogeomorphic surface) and contains at least 70 cm of stratified Paleoindian cultural deposits, all in floodplain and upper point‐bar facies. A suite of 36 radiocarbon ages indicates that the alluvium hosting the Paleoindian sequence aggraded between ca. 13,250 and 11,870 cal yr B.P. (11,380 and 10,180 14C yr B.P.). Underlying deposits accumulated between ca. 15,300 and 13,250 cal yr B.P. (12,950 and 11,380 14C yr B.P.). By ca. 11,250 cal yr B.P. (9,840 14C yr B.P.) the T1c paleogeomorphic surface was buried by the earliest increment of a thick sequence of overbank sheetflood facies, ultimately resulting in deep burial and preservation of the Paleoindian record. The landform‐sediment assemblage that hosts the Paleoindian and possibly earlier cultural deposits at Big Eddy is both widespread and well preserved in the lower Sac River valley. Moreover, the terminal Pleistocene and early Holocene depositional environments were favorable for the preservation of the archaeological record. © 2007 Wiley Periodicals, Inc.  相似文献   

4.
The Dog Creek archaeological site (NcVi‐3), located in the northern Yukon, provides evidence of complex site transformational processes related to microclimatic conditions occurring since the mid‐Holocene. Geoarchaeological research at Dog Creek sought to interpret site formation processes in order to understand the relationship between surficial artifacts, buried artifacts, and stratified sediments. It also attempted to reconstruct the periglacial processes that were active in transforming the site and their relationships to microclimatic conditions. Sedimentology and fabric analysis show that artifacts were buried by solifluction and disturbed by frost heave and cryoturbation. Radiocarbon dating and pollen analysis demonstrated that solifluction took place approximately 5200–2000 years ago when a spruce forest existed at the site. This evidence suggests an onset of cooling conditions that continues to the present. After the mid‐Holocene, the spruce treeline began to move south toward its present position. © 2001 John Wiley & Sons, Inc.  相似文献   

5.
Cactus Hill is located in the Virginia Coastal Plain on a terrace above the Nottoway River. The site has a record of occupation that spans the Holocene and also offers evidence of humans late in the Pleistocene before Clovis time. Soil investigations identified several deposit types, and demonstrated that multisequal eolian sands forming the site's primary core are arrayed in spatially and temporally discrete horizons. Resting atop an ancient paleosol, the earliest sand stratum (19,540 ± 70 14C yr B.P.) is marked by a conspicuous but culturally sterile buried surface horizon. Eolian sand above this surface supports another sequum in which Clovis and underlying “Blade” artifacts are associated with a fainter surface horizon and pronounced subsoil lamellae. Early Archaic and successively younger artifacts occur above the Clovis level in a more weakly developed uppermost sequum. This soil and cultural stratigraphy, together with considerations of regional topography, demonstrate that the landscape has evolved incrementally since about the last glacial maximum. © 2004 Wiley Periodicals, Inc.  相似文献   

6.
Ground-water, alluvium, and bedrock samples were collected from drill holes near the Chimney Creek, Preble, Summer Camp, and Rabbit Creek disseminated gold deposits in northern Nevada to determine if Au and ore-related metals, such as As, Sb, and W, are being hydromorphically mobilized from buried mineralized rock, and, if they are, to determine whether the metal-enriched ground water is reacting with the alluvial material to produce a geochemical anomaly within the overburden.Results of chemical analyses of drill-hole water samples show the presence of hydromorphic dispersion anomalies of Au, As, Sb, and W in the local ground-water systems associated with these deposits. Background concentrations for Au in the ground water up-gradient from the buried deposits was less than 1 nanogram per liter (ng/L), near the deposits the Au values ranged from 1 to 140 ng/ L, and in drill holes penetrating mineralized rock, concentrations of Au in the ground water were as high as 4700 ng/L. Highest concentrations of Au were found in ground-water samples where the measured Eh and the distribution of arsenic species, arsenite [As(III)] and arsenate [As(V)], indicated oxidizing redox potentials. Similarly, As, Sb, and W concentrations in the ground water near the deposits were significantly enriched relative to concentrations in the ground water up-gradient from the deposits. In general, however, the highest concentrations of As, Sb, and W occurred in ground-water samples where the measured Eh and the distribution of arsenic species indicated reducing conditions. Arsenic concentrations ranged from 9 to 710 micrograms per liter (μg/L); Sb, from less than 0.1 to 250 μg/L; and W, from 1 to 260 μg/L.In addition, analysis of sequential dissolution and extraction solutions of drill cuttings of alluvium and bedrock indicate geochemical anomalies of gold and ore-related metals in the overburden at depths corresponding to the location of the present-day water table. This relationship suggests that water-rock reactions around these buried deposits are active and that this information could be very useful in exploration programs for concealed disseminated gold deposits.  相似文献   

7.
Geoarchaeological investigations in western Middle Park provide important information for understanding the soil‐stratigraphic context of Paleoindian components, as well as the latest Quaternary environmental change and landscape evolution in a Southern Rocky Mountain intermontane basin. Paleoindian components are associated with the oldest two of four latest Quaternary stratigraphic units (1–4) recognized in co‐alluvial mantles (combined slopewash and colluvium) in uplands and in alluvial valley fills. Limited data suggest accumulation of unit 1 as early as ∼12,500 14C yr B.P. in alluvial valleys and by at least ∼11,000 14C yr B.P. in uplands was followed by brief stability and soil formation. A relatively widespread disconformity marks earliest Holocene erosion and substantial removal of latest Pleistocene deposits in upland and alluvial settings followed by unit 2 deposition ∼10,000–9000 14C yr B.P., perhaps signaling the abrupt onset of an intensified summer monsoon. In situ Paleoindian components in uplands are found in a moderately developed buried soil (the Kremmling soil) formed in units 1 and 2 in thin (≤1m) hillslope co‐alluvial mantles. The Kremmling soil reflects geomorphic stability in upland and alluvial settings ∼9000–4500 14C yr BP, and represents a buried landscape with the potential to contain additional Paleoindian components, although elsewhere in western Middle Park Early Archaic components are documented in morphologically similar soils. Kremmling soil morphology, the relative abundance of charcoal in unit 2 relative to younger units, and charcoal morphology indicate the expansion of forest cover, including Pinus, and grass cover during the early and middle Holocene, suggesting conditions moister than present. © 2010 Wiley Periodicals, Inc.  相似文献   

8.
J.L. Ripley 《Geoarchaeology》1998,13(8):793-818
Archaeological sites that have only surface scatters are usually considered to be of little or no use in reconstructing paleoenvironmental conditions during episodes of human occupation. However, geoarchaeological research at the Skare site in south-central Wisconsin reveals that these sites can be used to provide information about the timing of paleoenvironmental changes and their affect on the location of human occupations. Geomorphic investigations revealed the presence of Alfisols formed in late Wisconsin loess on upland and low bench positions; morphologically younger Mollisols formed in alluvial and colluvial sediments on low alluvial plain positions; and beach sediments that represent the low-water stand of Glacial Lake Yahara. Semiquantitative age control for timing the formation of these soils and the lake level(s) of Glacial Lake Yahara is based on the location of diagnostic artifacts (Early Paleoindian to Late Woodland) recovered during ten separate surface collections. Early and Late Paleoindian artifacts all occur on Alfisols and are only found above the low-water stand of Glacial Lake Yahara, indicating that loess deposition and subsequent soil formation happened sometime between 12,000 and 11,000 yr B.P., and that Glacial Lake Yahara remained near the low-water stand at least until ∼9500 yr B.P. Early Archaic artifacts are present below the low-water stand and provide ages for lowering of the lake to be between 8000 and 9500 yr B.P. Middle Archaic artifacts are present on Mollisols and provide an age of soil formation to be between 5000 and 3000 yr B.P. A majority of Woodland artifacts occur on these Mollisols and are present along the floodplain of the Yahara River, possibly representing a change in subsistence strategy and settlement patterns relative to Paleoindian and Archaic occupations. The agreement of soil morphological and sedimentological data with semiquantitative age data of diagnostic artifacts provides evidence that archaeological surface scatters can be useful tools in dating soils and landforms associated with these sites. © 1998 John Wiley & Sons, Inc.  相似文献   

9.
The combination of previously published pedological and phytolith analyses with new information on the geology, palynology, and an innovative analysis of archaeological chipped stone remains (including backplots, cluster analyses of artifacts, and chipped stone refitting) clarifies the environment and site formation of the mid-Holocene deposits at the Laddie Creek site, Wyoming. Palynological analyses strengthen the argument made by Reider and Karlstrom (1987) that the site was slightly wetter and warmer during the Altithermal (7500–5000 B.P.). The mid-Holocene environment at the site was conductive to the formation of soils and the preservation of archaeological deposits. A Cody Complex level associated with a colluvial C horizon provides evidence of greater movement of this material than that seen in the multiple Early Plains Archaic occupations associated with four A-horizons. The cultural levels identified in laboratory analyses are palimspsests deposited during multiple occupations.  相似文献   

10.
辽宁北部秀水地区中侏罗统地层的厘定及其地质意义   总被引：1，自引：0，他引：1  
通过开展油气基础地质调查,对分布于辽宁北部秀水河子一带的含煤岩系进行了钻孔岩心资料、岩性组合和古生物化石特征的研究。结果表明,该套含煤岩系地层时代为中侏罗世,可以与辽宁西部地区的海房沟组对比。该套地层的厘定为研究区构造演化、油气地质勘探寻找中侏罗统烃源岩层提供了重要的基础地质资料。  相似文献   

11.
Middle Park, a high‐altitude basin in the Southern Rocky Mountains of north‐central Colorado, contains at least 59 known Paleoindian localities. At Barger Gulch Locality B, an extensive Folsom assemblage (˜10,500 14C yr B.P.) occurs within a buried soil. Radiocarbon ages of charcoal and soil organic matter, as well as stratigraphic positions of artifacts, indicate the soil is a composite of a truncated, latest‐Pleistocene soil and a younger mollic epipedon formed between ˜6000 and 5200 14C yr B.P. and partially welded onto the older soil following erosion and truncation. Radiocarbon ages from an alluvial terrace adjacent to the excavation area indicate that erosion followed by aggradation occurred between ˜10,200 and 9700 14C yr B.P., and that the erosion is likely related to truncation of the latest‐Pleistocene soil. Erosion along the main axis of Barger Gulch occurring between ˜10,000 and 9700 14C yr B.P. was followed by rapid aggradation between ˜9700 and 9550 14C yr B.P., which, along with the erosion at Locality B, coincides with the abrupt onset of monsoonal precipitation following cooling in the region ˜11,000–10,000 14C yr B.P. during the Younger Dryas oscillation. Buried soils dated between ˜9500 and 8000 14C yr B.P. indicate relative landscape stability and soil formation throughout Middle Park. Morphological characteristics displayed by early Holocene soils suggest pedogenesis under parkland vegetation in areas currently characterized by sagebrush steppe. The expansion of forest cover into lower elevations during the early Holocene may have resulted in lower productivity in regards to mammalian fauna, and may partly explain the abundance of early Paleoindian sites (˜11,000–10,000 14C yr B.P., 76%) relative to late Paleoindian sites (˜10,000–8000 14C yr B.P., 24%) documented in Middle Park. © 2005 Wiley Periodicals, Inc.  相似文献   

12.
The Dry Creek archeologic site contains a stratified record of late Pleistocene human occupation in central Alaska. Four archeologic components occur within a sequence of multiple loess and sand layers which together form a 2-m cap above weathered glacial outwash. The two oldest components appear to be of late Pleistocene age and occur with the bones of extinct game animals. Geologic mapping, stratigraphic correlations, radiocarbon dating, and sediment analyses indicate that the basal loess units formed part of a widespread blanket that was associated with an arctic steppe environment and with stream aggradation during waning phases of the last major glaciation of the Alaska Range. These basal loess beds contain artifacts for which radiocarbon dates and typologic correlations suggest a time range of perhaps 12,000–9000 yr ago. A long subsequent episode of cultural sterility was associated with waning loess deposition and development of a cryoturbated tundra soil above shallow permafrost. Sand deposition from local source areas predominated during the middle and late Holocene, and buried Subarctic Brown Soils indicate that a forest fringe developed on bluff-edge sand sheets along Dry Creek. The youngest archeologic component, which is associated with the deepest forest soil, indicates intermittent human occupation of the site between about 4700 and 3400 14C yr BP.  相似文献   

13.
Carbonate staining has long been utilized with thin sections. Similar techniques are also extremely useful for distinguishing the mineralogy and texture of different carbonate minerals in drill cores. The simplest method for routine staining of whole drill core utilizes a dilute hydrochloric acid solution containing both alizarin red S and potassium ferricyanide. This solution is painted on to the drill core to allow for the rapid identification of calcite, ferroan calcite, ferroan dolomite (ankerite), and rhodochrosite. Production-scale staining of whole drill core rapidly provides a wealth of information on carbonate mineralogy and textural relationships in a number of deposit types. Examples from the Irish Zn-Pb district, the McArthur River Zn-Pb-Ag district, the Ruby Creek Cu-Co deposit, and the Kansanshi copper deposit are presented to illustrate the type of information that can be gained through use of this inexpensive and rapid technique.  相似文献   

14.
A soil geochemistry orientation survey for U at Koongarra was designed to determine optimum conditions for future U exploration in the area. Soil samples were collected at various depths from auger holes drilled along two traverses over the Koongarra No. 1 orebody, along a single traverse over suspected mineralization at nearby Anomaly A, and at three background localities. Rock samples collected from surface outcrop, costeans, and drill core were used to investigate any elemental associations with the ore or primary dispersion which could then be traced in the overlying soils.The results showed that Cu and Pb are potentially suitable pathfinder elements, where U data are not definitive, while Co, Ni and Be also provide significant information. The optimum sample depth was 1.2 m. For a Koongarra-sized target the maximum sample spacing should be 30 m on lines 200 m apart, provided every anomalous sample is followed up with closer spaced sampling around it. Anomalies detected in alluvial soil deeper than 1.2 m were due to hydromorphic dispersion. Some of the general distribution patterns for individual elements may be related to soil-type variations.  相似文献   

15.
Controlled by a local base level of downfaulted Edwards and Comanche Peak limestone, and aided by landsliding in Glen Rose marl, the Sabinal River and its tributaries have developed a large valley in the Edwards Plateau. Extensive soil-covered pediments that cut Glen Rose bedrock and Pleistocene terrace gravels are present along each side of the valley. Six alluvial deposits of late Pleistocene and Holocene age were recognized in the upper Sabinal River valley. The Holocene series is represented by three deposits. The oldest of these exhibits a Stage II calcic horizon and appears to have been deposited before ca. 5000 yr B.P. The Pleistocene deposits have a calcrete zone (calcic Stage IV and III horizon) in the upper 3-4 m. The Holocene alluviums, locally beveled by stream action, parallel the river's course and contain Archaic and younger artifacts, which in central Texas range in age from about 8000-350 yr B.P. One of the Holocene deposits (Q2) is correlated with the Georgetown and Fort Hood alluviums of the Cowhouse Creek at Fort Hood, which range in age from 11,000 yr B.P. to 5200 yr B.P., with the Wilson-Leonard terrace site in the Lampasas Cut Plain that ranges from about 11,000 to 5000 yr B.P., and with Unit E of Blum and Valastro (1989) in the Pedernales River valley, ranging from 10,550 to 7150 yr B.P. Modern climate in the valley is drought-prone, and fluctuates from semiarid to dry subhumid. Paleoclimate has ranged from much drier during the Middle Holocene to much cooler and wetter during the Late Pleistocene.  相似文献   

16.
Soil-sediment records and radiometric dating allow the development of environmental histories of three South Platte River alluvial terraces in the vicinity of Kersey, Colorado. These advocate a correlation with Holocene glacial records for the Colorado Front Range (Benedict, 1981, 1985). The archaeological potential of the Kersey fill, the Kuner strath, and the Hardin fill depends upon their age and sediment context. The oldest and most extensive terrace is the Kersey fill. The position of cultural components on the Kersey terrace implies an association of older Paleoindian sites (11,500–10,000 B.P.) with channel banks and bars on the terrace, younger Paleoindian sites (<10,000 B.P.) with terrace margins near the river, and Archaic and younger sites with eolian deposits on the terrace. An association of Clovis components with both Kersey alluvium and adjacent eolian dune fields indicates that eolian deposition began prior to 11,000 B.P. and that sediment availability influenced early Holocene eolian deposition. Examination of 150 cores and 75 backhoe test units along an 8-km study corridor demonstrates that Paleoindian sites are not as abundant on the Kersey terrace as previous researchers have proposed. Although the incision of the Kuner strath began earlier than 9600 B.P., we propose that its greatest potential is to yield cultural components that postdate ca. 7250 B.P. In turn, the Hardin fill may yield cultural components dating to the Kuner abandonment (ca. 6380 B.P.). However, Hardin sediment and soil records recommend that this fill terrace's highest potential is to yield in situ cultural components dating from ca. 1900 to 120 B.P. © 1994 John Wiley & Sons, Inc.  相似文献   

17.
针对孟津煤矿二2煤层弱突出危险性的特点,以及11031工作面胶带、轨道顺槽掘进速度缓慢的问题,研究不同孔径钻孔的卸压范围和抽放效果。采用大直径钻孔,钻孔分区式布置对现有区域消突技术进行优化,孔径113 mm的抽放钻孔单孔抽放瓦斯纯量为孔径94 mm的1.8倍。表明大径顺层长钻孔的应用,能够有效消除煤巷预抽条带瓦斯突出危险,提高掘进速度,确保掘进工作面的安全生产。   相似文献   

18.
In a dry valley near Ventnor, Isle of Wight, thick subaerial slope deposits of Devensian Late-glacial age overlie the Chalk. The deposits are crudely stratified chalk muds and rubble produced by frost-shattering, and moved downslope by the release of water from melting snow-fields and frozen ground. A laterally extensive humic horizon of a rendzina soil occurs within the sequence, clearly reflecting a period of relative slope stability. In places this horizon divides and its upper surface appears to have been disturbed, possibly by cryoturbation. Micromorphological and other analyses confirm the pedogenic origin of this humic horizon, but also demonstrate the occurrence of pedological features both above and below it. The humic horizon therefore is not a ‘buried’ soil in the strictest sense, but is part of a vertical sequence representing a single complex soil with transported, accretionary and welded components. Molluscan analyses reveal that the sequence can be divided into four local mollusc zones, showing a progressive increase in faunal diversity throughout the profile. This succession is broadly similar to other Late-glacial sequences described from south-east England. Minute fragments of charcoal from the lower part of the humic horizon have yielded an AMS date of 11690 ± 120 vr BP, demonstrating formation during the ‘Allerød phase’ of the Late-glacial Interstadial. This humic horizon is correlated provisionally with the ‘Pitstone Soil’, even though existing dates from its type-site in Buckinghamshire are somewhat younger.  相似文献   

19.
Investigations were conducted along the middle South Platte River to better define the geomorphic contexts of Paleoindian sites and to reconstruct the alluvial and eolian geochronology. Paleoindian sites are associated with the Kersey terrace (the downstream equivalent of the Broadway terrace). The Kersey alluvium was deposited during Clovis occupation and the surface stabilized by 10,000 B.P. Post-Clovis sites post-date aggradation and stream downcutting may have started as early as 10,500 B.P. Subsequent floodplain development and downcutting formed the Kuner terrace (the possible downstream equivalent of the Piney Creek terrace) no later than 3000 B.P. and the Hardin terrace probably within the last 1000 years. Soils on the Kersey terrace are Ustochrepts (gravelly alluvium) or Haplustalfs (sandy and clayey alluvium). Soils on the Kuner terrace are cumulic Ustorthents and Ustochrepts. Soils on the Hardin terrace are Ustorthents with no obvious horizonation. Eolian sands began accumulating in the region by 10,000 B.P., but most are probably late Holocene deposits and are indicative of drier post-Pleistocene climate. Correlations with deposits in low order tributaries and other drainages can be difficult to make a) using soils because soil development varies as a function of parent material texture and b) because aggradation and degradation may be out-of-phase.  相似文献   

20.
Sedimentological, faunal, and archaeological investigations at the Sunshine Locality, Long Valley, Nevada reveal a history of human adaptation and environmental change at the last glacial–interglacial transition in North America's north-central Great Basin. The locality contains a suite of lacustrine, alluvial, and eolian deposits associated with fluvially reworked faunal remains and Paleoindian artifacts. Radiocarbon-dated stratigraphy indicates a history of receding pluvial lake levels followed by alluvial downcutting and subsequent valley filling with marsh-like conditions at the end of the Pleistocene. A period of alluvial deposition and shallow water tables (9,800 to 11,000 14C yr B.P.) correlates to the Younger Dryas. Subsequent drier conditions and reduced surface runoff mark the early Holocene; sand dunes replace wetlands by 8,000 14C yr B.P. The stratigraphy at Sunshine is similar to sites located 400 km south and supports regional climatic synchroneity in the central and southern Great Basin during the terminal Pleistocene/early Holocene. Given regional climate change and recurrent geomorphic settings comparable to Sunshine, we believe that there is a high potential for buried Paleoindian features in primary association with extinct fauna elsewhere in the region yet to be discovered due to limited stratigraphic exposure and consequent low visibility.  相似文献   

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