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1.
Surface water on the mainly dry, upland interfluves of the Upper Coastal Plain of South Carolina occurs currently as a sporadic distribution of shallow ponds held within Carolina bays and other small, isolated basins. At seven bays on the U.S. Department of Energy's Savannah River Site on the Upper Coastal Plain of South Carolina, we investigated Holocene changes in bay morphology, ecology, and prehistoric human activity. At Flamingo Bay, we employed archaeological survey and testing, shovel and auger testing, sediment analysis, and ground-penetrating radar to document stratigraphy and chronology of the sand rim on the eastern side of the bay. Artifact assemblage indicate changes in intensity of human use of the bay. Radiocarbon dates from a sediment core establish time scales for depositional processes at the center of the basin. Ground-penetrating radar data from the other bays indicate that the stratigraphy of all seven bays is broadly similar. We conclude that: (1) Significant modification of the bays, including rim development and basin infilling, occurred during the Holocene; (2) ponds on the early Holocene landscape were larger and more permanent than at present; (3) early Holocene climate, as indicated by both depositional processes and human activity, was not characterized by prolonged periods of extremely dry conditions; and (4) fluvial-centric models of terminal Pleistocene—early Holocene human adaptations require revision to include intensive use of isolated upland ponds. © 1996 John Wiley & Sons, Inc.  相似文献   

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Chrono-stratigraphic data from Tyre's ancient northern harbour delineate extensive dredging practices during the Greco-Roman and Byzantine periods. Radiocarbon dates from four cores consistently cluster between ca. 500 B.C. and 1000 A.D. and indicate rapid rates of sedimentation in the basin, namely ∼10 mm/yr during the Greco-Roman and Byzantine periods, compared to 0.5-1 mm/yr for the period 6000-4000 B.C. Absence of strata between 4000 B.C. and 500 B.C. is not consistent with a natural base-level sediment sink and cannot be interpreted as a depositional hiatus in the high-stand systems tract. Ancient dredging is further corroborated by persistent age-depth inversions within the fine-grained harbour facies. These data support removal of Middle Bronze Age to Persian period sediment strata, with deliberate overdeepening of the harbour bottom by Greco-Roman and Byzantine societies.  相似文献   

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Interpretation of Shuttle Imaging Radar (SIR) images acquired during the November 1981 flight of Columbia led to the idea that a paleodrainage system of regional and perhaps transcontinental proportions crossed southern Egypt and northern Sudan prior to the onset of Quaternary aridity. Three seasons of field investigations in two locales (Wadi Arid and Wadi Safsaf, some 70-80 km apart) near the Sudan border of southern Egypt confirmed initial interpretations of the radar images and produced geologic evidence of fluvial deposition in broad “radar river” valleys (designated RR-1) whose presence is now obscured by eolian sand sheets. Development of an integrated, regional river system probably occurred in the late Paleogene or early Neogene. the river courses eventually were disrupted by tectonism, volcanism, and stream piracy. Their broad valleys were almost fully aggraded long before the middle Pleistocene appearance of man in the area. Some of the large paleovalleys on the radar images contain narrow (0.05-2.0 km wide), braided inset channels (designated RR-2). the RR-2 channels, we believe, represent the last episodes of running water in the valleys during the Quaternary pluvials. In Wadi Arid (the type area for the RR-1 valleys) 36 backhoe trenches and manual excavations yielded Acheulian handaxes, flakes, and cores from nearshore alluvial sediments and surface and shallow subsurface locales. These assemblages are typologically Middle to Late Acheulian and date from ca. 0.15th 0.5 million years ago. the unabraded, unrolled, buried artifacts and their geological contexts indicate that human groups were widely present in a subhumid riparian environment along the edges of the ancient valleys, while these localities were undergoing episodic, local aggradation. Scarce Middle Paleolithic and abundant Neolithic assemblages are widespread along the edges of Wadi Arid and bordering interfluves. In Wadi Safsaf, another broad RR-1 valley, geologic evidence from 20 backhoe excavations demonstrates that an RR-2 channel complex is inset into the alluvial fill in the central part of the valley. No artifacts were found in the alluvium excavated there, but Late Acheulian, Middle Paleolithic, and Neolithic surface assemblages are present nearby. Stratigraphic relations indicate the RR-2 channels are late Pleistocene in age; they were already fully aggraded and their surfaces deflated before an eolian sand sheet of Holocene age was deposited on them. Bir Safsaf, on the northern edge of Wadi Safsaf, was a magnet for Late Acheulian populations, and the paleovalley just south of the bir is bordered with extensive alignments of artifacts, mainly handaxes. Some of these handaxes were found in situ, embedded in alluvial sediments, while others appear to have been exposed on the surface by deflation of the valley fill. The accumulated data support a provisional archaeo-geochronological framework for the last half-million years in the Wadi Arid-Wadi Safsaf area. This framework provides a new geomorphic explanation for the widespread distribution of buried and exposed Middle Acheulian and Late Acheulian assemblages. the interpretation emphasizes the importance of exploring the non-oasis zones for their archaeological and geochronological potential. Although our research has literally only scratched the surface, it demonstrates the potential of radar imaging for defining ancient drainage patterns in arid regions and their associated habitats for human occupation.  相似文献   

4.
Many laboratory techniques are available to geoarchaeologists to determine physical or chemical attributes of sediment or soil samples, and several techniques are often available for analysis of a single attribute. This is illustrated by analyzing duplicate sediment and soil samples from the British Camp Site (Washington) and Lubbock Lake Site (Texas) using two methods for organic carbon content, two methods for organic matter content, and three methods for calcium carbonate content, and several pretreatment procedures for particle-size analysis. These comparisons illustrate that different methods of analysis for the same property of duplicate samples can yield different results. Therefore, when making comparisons with data from other sites or other investigators, the types of laboratory methods used in geoarchaeological analyses are important considerations. Choice of a particular technique will depend on a variety of factors, often conflicting, including the archaeological and geoarchaeological questions being asked, the physical and chemical nature of the samples, and the accuracy, efficiency, and cost of the method.  相似文献   

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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   

9.
The sedimentary sequence discovered at archaeological excavations in ancient Theodosius Harbour at İstanbul contains the records of sea level, environmental changes and the cultural history of the region. The cobbles at the base of the sequence include archaeological remnants of Neolithic culture that settled in the area between 8.4 and 7.3 14C ka BP, and are located at 6 m below the present sea level. The sediments representing a coastal environment indicate that the area was used as a harbour from AD 4th to at least the 11th century and were filled by the sediments derived from Lykos Stream after 11th century.  相似文献   

10.
Perspectives on the geoarchaeology of the Lower Mississippi Valley   总被引:1,自引:0,他引:1  
The impact of Harold N. Fisk's work on the archaeology and geoarchaeology of the Lower Mississippi Valley (LMV) has been monumental. As a result of his landmark publications on the geology of the alluvial valley of the Mississippi River our comprehension of the interplay between geological, geomorphic, and human actions is relatively well developed. However, geologists and archaeologists still need to work together more closely to appreciate and understand the contributions each field has to offer. Examination of the interplay between geologists and archaeologists in the realm of dating and landscape evolution provides the basis for an investigation of the state of geoarchaeology in the LMV today. Integration of research demands an appreciation of scale which must be approached from an historical perspective. Humans have, both in the past and the present, impacted the natural environment of the Mississippi River and its floodplain. Only when this fact is fully appreciated by archaeologists and geologists alike will it be possible to forge a new synthesis of the relationship between the dynamic alluvial valley and its human occupants.  相似文献   

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Geoarchaeological investigations in an area surrounding the confluence of the upper Colorado and Concho Rivers, Edwards Plateau of West Texas, have produced a detailed landscape evolution model which provides a framework for discussion of the influences of geomorphic processes on the development, preservation, and visibility of the archaeological record. Field mapping within the study area has differentiated six allostrati-graphic units of fluvial origin in both valleys, as well as extensive eolian sand sheets along the Colorado River. Early to middle Pleistocene terrace remnants cap many upland areas, whereas two distinct late Pleistocene terrace surfaces are widespread within the study area at somewhat lower elevations. Fluvial activity during the time period of human occupation is represented by an extensive Holocene terrace and underlying valley fill, which is up to 11 m in thickness. Valley fill sediments can be subdivided into allostratigraphic units of early to middle Holocene (ca. 10,000–5000 yr B.P.) and late Holocene age (ca. 4600–1000 yr B.P.), which are separated by a buried soil profile. The modern incised channels and very narrow floodplains represent the last millennium. Eolian sand sheets of early to middle Holocene age overlie limestone- and shale-dominated uplands, Pleistocene terraces, and in some cases the Holocene valley fill along the Colorado River. Pleistocene terraces have been stable features in the landscape and available for settlement through the time period of human occupation. Archaeological materials of all ages occur at the surface, and the record preserved in individual sites range from that associated with discrete periods of activity to longer-term palimpsests that represent repeated use over millennia. Sites within early to middle Holocene and late Holocene fills represent short-term utilization of constructional floodplains during the Paleoindian through early Archaic and middle to late Archaic time periods respectively. By contrast, those that occur along the buried soil profile developed in the early to middle Holocene fill record middle to late Archaic cultural activity on stable terrace surfaces, and represent relatively discrete periods of activity to longer-term palimpsests that represent repeated use over the 3000–4000 years of subaerial exposure. Late Prehistoric sites occur as palimpsests on soils developed in late Holocene alluvium or stratified within modern floodplain facies. Paleoindian through Late Prehistoric sites occur stratified within eolian sand sheets or along the unconformity with subjacent fluvial deposits. The landscape evolution model from the upper Colorado and Concho Rivers is similar to that developed for other major valley axes of the Edwards Plateau. This model may be regionally applicable, and can be used to interpret the geomorphic setting and natural formation processes for already known sites, as well as provide an organizational framework for systematic surface and subsurface survey for new archaeological records. 0 1992 John Wiley & Sons, Inc.  相似文献   

13.
This study provides new information on the evolution of the Tiber delta during the late Holocene, and describes the record of sedimentation in the Port of Claudius and Trajan. The Tiber flowed into the Tyrrhenian Sea in the area of the Port of Claudius and Trajan between the 8th and 5th centuries B.C. The harbor basins excavated by the Romans during the 1st and 2nd centuries A.D. were filled with sediments containing saltwater fauna, then brackish‐water fauna, and finally by alluvial and marsh deposits. The Port of Claudius and Trajan was silted in as a consequence of episodes of alluviation that correlate with environmental events, possibly triggered by global climate changes. © 2009 Wiley Periodicals, Inc.  相似文献   

14.
Two approximately 5‐ to 6‐km drainage segments on Black Mesa preserve unusually complete sequences of late Quaternary alluvium and soils. Radiocarbon‐ and tree‐ring‐dated alluvial and soil stratigraphy suggests entrenched paleoarroyos were beginning to aggrade at about >24,260, 11,070, 9660, 8800, 7060, 3500, 2140, and 1870 14C yr B.P. Using the quantity of sediment removal from post‐A.D. 1900 arroyos as analogue, at least 77–200% of total valley alluvium has been removed and replaced by younger sediments during an estimated 11 late Pleistocene and Holocene erosion epicycles. Given that most (59%) of the 150 recorded prehistoric sites in the two study areas occur on valley floors where only about 3% of surface alluvium predates Lolomai phase Basketmaker II occupation (˜1900–1600 yr B.P.), it may be inferred that pre‐Lolomai phase Basketmaker II sites which may have been located along washes have been removed or buried by fluvial erosion. Identification of five buried hearths in alluvial sections, including White Dog and Lolomai phase Basketmaker II sites (dating about 3500 and 1870 14C yr B.P., respectively) and one possible Early Archaic site, supports this conclusion. © 2005 Wiley Periodicals, Inc.  相似文献   

15.
The Fourth of July Valley site (5BL120) occupies the crest and inner slope of a Satanta Peak (latest Pleistocene) terminal moraine above timberline in the Indian Peaks Wilderness Area, Colorado Front Range. Excavations in 1971 suggested that a Late Paleo‐Indian lithic tradition marked by lanceolate and stemmed projectile points with parallel‐oblique flaking persisted at high altitude during the Altithermal, long after its disappearance from drought‐susceptible lowlands. Analysis of a sediment column collected in 2001 casts doubt on this interpretation. Large charred sclerotia (the resting stages of mycorrhizal fungi) show that tree islands colonized the moraine soon after deglaciation, fueling Early and Middle Holocene wildfires. Conditions became increasingly periglacial ca. 3340 yr B.P., when a lobate rock glacier advanced to the south margin of the site, altering snow‐accumulation patterns, eliminating trees, supplying meltwater that fueled ice‐lens formation, and initiating deposition of humus‐rich, snowbed loess. Large waste flakes and artifacts were frost‐sorted to the existing ground surface, where they became mixed with 6240‐year‐old wildfire charcoal in a pseudo‐occupation layer. Microflakes were too small to participate in vertical frost sorting, so remained in their original stratigraphic locations. The association of thermally altered microflakes with 8920‐year‐old charcoal in a deeply buried stratigraphic context suggests that the site was occupied during the Early Holocene and is irrelevant to the Altithermal refugium hypothesis. © 2005 Wiley Periodicals, Inc.  相似文献   

16.
Holocene evolution and human occupation of the Sixteen Mile Beach barrier dunes on the southwest coast of South Africa between Yzerfontein and Saldanha Bay are inferred from the radiocarbon ages of calcareous dune sand, limpet shell (Patella spp.) manuports and gull-dropped white mussel shells (Donax serra). A series of coast-parallel dunes have prograded seaward in response to an overall marine regression since the mid-Holocene with dated shell from relict foredunes indicating periods of shoreline progradation that correspond to drops in sea level at around 5900, 4500 and 2400 calibrated years before the present (cal yr B.P.). However, the active foredune, extensively covered by a layer of gull-dropped shell, has migrated 500 m inland by the recycling of eroded dune sand in response to an approximate 1 m sea level rise over the last 700 yr. Manuported limpet shells from relict blowouts on landward vegetated dunes indicate human occupation of coastal dune sites at 6200 and 6000 cal yr B.P. and help to fill the mid-Holocene gap in the regional archaeological record. Coastal midden shells associated with small hearth sites exposed in blowouts on the active foredune are contemporaneous (1600-500 cal yr B.P.) with large midden sites on the western margin of Langebaan Lagoon and suggest an increase in marine resource utilisation associated with the arrival of pastoralism in the Western Cape.  相似文献   

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《GeoJournal》1995,37(4):569-570

Reports

Ocean and Coastal Management  相似文献   

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A multidisciplinary study was undertaken at the Qijurittuq Site (IbGk‐3) on Drayton Island in Low‐Arctic Quebec (Canada) to document the relationships between climatic, environmental, and cultural changes and the choice of Thule/Inuit dwelling style in the eastern Arctic. Several marine terraces were 14C‐dated with shells in order to reconstruct the area's uplift (glacioisostatic rebound) curve. Plant macrofossil analysis of peat was conducted to reconstruct past vegetation and, indirectly, past climate. Archaeological surveys and excavations characterized the structure of subterranean sod houses at the Qijurittuq Site and were supplemented with open interviews with Inuit elders for a better understanding of site location and the use of household space. The sites selected for habitation were well‐drained sandy marine terraces in a valley sheltered from prevailing winds. Sod houses were in turn made possible by the abundance of driftwood on the island and the presence of nearby peatland. Thule/Inuit people used semi‐subterranean houses rather than igloos at the Qijurittuq Site during the dry, cold conditions toward the end of the Little Ice Age. Stable environmental conditions and food supply during winter possibly explain the use of those semipermanent houses on Drayton Island. However, it does not exclude the use of igloos during short expeditions on ice. © 2011 Wiley Periodicals, Inc.  相似文献   

20.
Palaeoseismological and archaeological analysis of a trench enabled us to estimate the Holocene slip rates on the East Helike Fault, flanking the south-western Gulf of Corinth. We recognized two major fault strands within the trench: the ‘north fault’ controls a succession of three colluvial wedges and the deposition of a 2.7 m thick sedimentary sequence. The ‘south fault’ controls the deposition of a 2.9-m thick brownish-red colluvium. Based on colluvial stratigraphy, radiocarbon dating of the sediments suggests that the slip rate was c. 0.3 mm yr−1 from 10 250 to c. 1400 bp , when it increased dramatically to c. 2.0 mm yr−1 after a strong earthquake event near 1400 bp . The faster slip rate evidently increased the sedimentation rate.  相似文献   

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