The surface archaeological record in arid Australia: Geomorphic controls on preservation,exposure, and visibility

The conventional approach to assessing the archaeological record in most parts of the world involves a combination of excavation of stratified deposits and extensive survey of surface deposits. Although widely applied in Australia, in both research‐based and management archaeology, the method does not conform well to the nature of the surface archaeological record here. Over much of semi‐arid and arid Australia, archaeological “sites” are, in fact, accretion phenomena that are not easily interpreted as the outcome of short‐term behavioral events. Using results from twelve years of geoarchaeological research in western New South Wales, we demonstrate that there is considerable variability in landsurface age, and hence the “availability” of archaeological surfaces, over relatively short distances. Therefore, it cannot be assumed that stone artifact deposits, for example, that appear to be similar in character are of similar age. Data are also presented that demonstrate that the presence of artifacts on the surface, their apparent absence in sediments buried beneath the surface, and the apparent recent ubiquity of the archaeological record are all a function of geomorphic processes that, at the same time, expose some artifact deposits at the surface and erode and bury others amid large volumes of sediment. Interpreting the surface artifact record within a spatial and temporal geomorphic framework is crucial to understanding the past human behavior that the artifact deposits represent. © 2009 Wiley Periodicals, Inc.     

Desert Pavement Disturbance and Artifact Taphonomy: A Case Study from the Eastern Libyan Plateau,Egypt

Accretionary desert pavements on the eastern Libyan Plateau of central Egypt support a rich Middle and Upper Paleolithic artifact assemblage exhibiting intensive blank production and minimal tool production. These assemblages appear to be in primary context with numerous examples of lithic refits showing on‐site lithic production. However, the smallest (length ≤2.5 cm) archaeological fragments are recovered at a much lower rate on this desert pavement surface than expected given comparable data from lithic assemblages in cave and shelter contexts in France. Excavation of archaeological contexts on the Libyan Plateau reveals the loss of small artifact fragments into the subsurface due to aeolian accumulation of silts, whereas geomorphic examination of desert pavement surfaces suggests a potential for relatively isolated bioturbation as a source of lateral and vertical disturbance of desert pavement surfaces over small areas. Archaeologists should be aware of the potential for long‐term assemblage stability as well as small artifact burial in surficial desert pavement contexts.     

Single‐Grain Luminescence Dating of Sediment Surrounding a Possible Late Pleistocene Artifact from the Wenas Creek Mammoth Site,Pacific Northwest,USA

Excavations at the Wenas Creek Mammoth Site yielded mammoth, bison, and two possible artifacts in a single colluvial stratum, with radiocarbon bone dates ∼17 ka. Eight infrared‐stimulated luminescence (IRSL) samples were collected to establish general ages of site strata, returning multi‐grain estimates consistent with stratigraphic integrity and the radiocarbon dates. Four additional IRSL samples were collected to estimate the depositional age of one artifact found in place. These produced a pooled total of 94 single‐grain estimates from near the artifact, 80% averaging 16.8 ± 0.9 ka, and 20% averaging 5.1 ± 0.5 ka. These results could be interpreted to demonstrate pre‐Clovis age artifact deposition consistent with the bone dates, or a mid to late Holocene intrusion into older deposits, possibly by bioturbation. The single‐grain IRSL dates do not provide proof of pre‐Clovis presence beyond reasonable doubt at this site, but do show that this technique is valuable in assessing the stratigraphic integrity needed for any such claim.     

Hydrologic artifact dispersals at Pingasagruk,North Coast,Alaska

Situated on a coastal sand bar, Pingasagruk is a habitation site with prehistoric and historic components. Data from systematic surface sampling led to analyses that show different artifact distribution patterns on and off this site and suggest the dispersals are due to storms and erosion, in addition to human activity. To explain the disparate distributions of cultural materials, this study uses a model of hydrologic artifact dispersal and, possibly, differential sorting. Differences in distribution patterns at Pingasagruk highlight the importance of considering how cultural and noncultural transformation processes affect the occurrence of sites and their artifacts. © 1993 John Wiley & Sons, Inc.     

Paleoeskimo site taphonomy: An assessment of the integrity of the Tayara site,Qikirtaq Island,Nunavik, Canada

A detailed taphonomic study was undertaken at the Tayara site in order to determine the impact of natural processes such as surface water flow on spatial patterning and site formation. The study focused on Paleoeskimo level II, which contains many lithics and significant faunal remains. Level II integrity was assessed through spatial analysis and by examining the size distribution of lithic artifacts and bone orientation. Experimental knapping aimed at replicating Paleoeskimo lithic technology was used to assess the possible size sorting of lithics. The study indicates that artifact burial by water‐laid sediments did not result in a selective impoverishment in small‐sized lithics. Statistically significant lithic concentrations and associations suggest that spatial distribution was not significantly modified by site formation processes. However, slight post‐depositional changes were presumably induced by water flows in the form of statistically significant horizontal bone reorientations. These occurred when gently flowing water inundated bone accumulations without inducing significant washing or sorting of smaller lithic debris. The spatial integrity evaluation of the level II assemblage reveals a low degree of spatial disturbance and disorganization of the material (i.e., limited entropy), which is likely related to low‐energy hydraulic forces and rapid burial soon after Paleoeskimo occupation. The grouping and deposition of much of the occupation debris is likely the result of Paleoeskimo activities (e.g., knapping and butchering), and the lithics and fauna specimens are probably at or very near their original location. These results show the behavioral significance of the grouping and deposition of debris in Tayara's level II. © 2009 Wiley Periodicals, Inc.     

Size distributions of artifact classes: Combining macro-and micro-fractions

The size and composition of microartifacts (objects less than 2 mm) and macroartifacts (objects greater than 2 mm) are utilized to interpret the formational processes of an archaeological site. Because grain-size distributions are known to reflect mode of transport and source, the attribute of size is examined by plotting each artifact class (unmodified rock, modified rock, ceramic, concretion, bone/shell, and metal) in size frequency diagrams. the plots allow the agent and mode of transport to be reconstructed, which in turn allows the formational processes of the site to be interpreted. the example used is the Pelts Site (23-DU-29) of southeastern Missouri. the site was chosen for this pilot study because the formation processes can be reconstructed from other data. the size distributions of each artifact class support those reconstructions and allow the proposed method to be evaluated as an interpretive method for other archaeological sites.     

Modeling the natural degradation of earthworks

Stratigraphic, topographic, and ground‐penetrating radar data obtained from a ca. 1800‐year‐old embankment and adjacent ditch at the Hopewell Mound Group (Chillicothe, Ohio) are used to validate the archaeological application of a simple finite‐differences diffusion model employed frequently to assess geomorphic change in natural landscapes. Although diffusion models have been used to describe the topographic degradation of landforms in a variety of geomorphic terrains, the approach has not been applied to ancient earthworks in an archaeological context. The results of this study indicate that a variety of initial earthwork forms can result in the sinusoidal profile apparent on the current landscape. Using the model results to interpret the field data, we suggest that the initial embankment form was steeper and the adjacent ditch was deeper. As a result of natural degradation processes, the earthwork widened and flattened over time. These results have broad implications for any study aimed at: (1) assessing the function of original earthwork forms, (2) determining the formation processes of complicated stratigraphies or artifact assemblages, (3) estimating the time and labor investment required for construction, or (4) identifying the socio‐political structures necessary to build earthworks. © 2005 Wiley Periodicals, Inc.     

Redistribution of archaeological assemblages in plowzones

Archaeological surface surveys have located open‐air sites on cropland in the Sierra de Atapuerca (Burgos, Spain). To what degree agricultural disturbances have impacted archaeological site integrity is poorly defined and may greatly affect interpretations of prehistoric land use. This paper presents the results of three experiments concerned with the effects of tillage on artifact distribution, focusing specifically on lateral and vertical artifact displacement. We demonstrate highly variable horizontal displacement of artifacts by plowing and overall downward movement of lithic materials within the soil. This results in an expansion of site boundaries and reduction of surface artifact density, yielding a biased and unrepresentative picture of past human activity. More experimental studies are needed to better define agricultural disturbances to surface archaeological assemblages. © 2008 Wiley Periodicals, Inc.     

Sheetfloods,sheetwash, sheetflow,or ... ?

Following McGee's (1897) use of the term sheetflood, there developed a variety of conflicting opinions and numerous terminologies relating to this process, many of which are ill-considered and poorly defined. A classification system is devised on both a hydrologic and geomorphic basis which dispenses with many superfluous terms that have been used with respect to sheetfloods. Magnitude of a storm is expressed in terms of the amount of surface runoff generated from a given storm due to the surface conditions.A sheetflood is defined as a sheet of unconfined flood water moving down a slope. The frequency of a sheetflood is relatively low while its magnitude is relatively great. Sheetflow is defined as relatively high-frequency, low-magnitude overland flow occurring in a continuous sheet and is restricted to laminar flow conditions. Sheetwash, a term of geomorphic origin, is considered to be redundant and is superseded by the more meaningful term rainwash defined as the washing action of rain on slopes.     

Site formation processes at Donggutuo: a major Early Pleistocene site in the Nihewan Basin,North China

Understanding site formation processes is crucial for interpreting archaeological context patterns and hominin behaviour as these affect the preserved condition of a site and the integrity of archaeological remains. The fluvio‐lacustrine sequences in the Nihewan Basin of North China are rich sources of early Pleistocene archaeological sites, which offer an important opportunity to investigate human evolution and adapted behaviours in East Asia. Although many Palaeolithic sites have been reported from the Nihewan Basin, North China, few of them focus on site formation processes before interpreting the hominin behaviour patterns. Here, we present a site formation study of four archaeological layers (Layers 6D, 6C, 6B and 6A) in Trench 1 from the Donggutuo (namely DGT‐T1) site in the Nihewan Basin with an age of 1.1 Ma. Through the study of sedimentary contexts, spatial distributions of artefacts and fossils, intra‐assemblage category ratios, debitage size distributions, lithic abrasion, artifact orientation and planar dip, our results show that all the layers had been disturbed by low‐energy sheet wash across the lake shore setting, but to differing extents. The post‐depositional disturbance caused by water decreased from the lower to the upper layers, from Layer 6D to Layer 6A. This indicates that the archaeological remains in DGT‐T1 have not been subject to significant natural modifications and are thus suitable for studying early hominin behaviour in North China. Copyright © 2019 John Wiley & Sons, Ltd.     

Evaluating artifact burial by eolian versus bioturbation processes,South Carolina Sandhills,USA

Artifacts are commonly buried by approximately 50 cm of sediment at prehistoric archeological sites (early Archaic through Mississippian) on uplands of the Sandhills of the upper Coastal Plain of the southeastern United States. Bioturbation, eolian sedimentation, and colluviation are the primary processes that can explain artifact burial because of the upland position of the sites in an erosional landscape setting. Colluvial sedimentation is discounted at most of the sites because they occur on interstream divides and upper hillslope positions. Thus, the focus is on eolian sedimentation versus bioturbation as burial agents. Six sites in the midst of the Sandhills region along the corridor of South Carolina Highway 151 in Chesterfield County provide the data. The Sandhills consist primarily of Cretaceous and Tertiary marine, fluvial, and eolian sediments that are highly dissected and overlie crystalline rocks in the deep subsurface. Two of the sites are on high fluvial terrace remnants that predate 12 ka and serve as controls where bioturbation is the only reasonable burial process. Hillslope positions of the sites are on erosional elements of the landscape (crests, shoulder slopes, and upper backslopes) where sediment transfer operates (colluvial and overland flow), but where deposition is minimal. The sites occur on very sandy soils having a texture of loamy sand to sand. In some instances, a fine textured cover sand, which is about 1.5 m thick, overlies a clayey subsoil or Bt horizon. This cover sand has been interpreted by some as an eolian sand sheet that buries a second parent material and paleosol, but standard particle size and heavy mineral data indicate that it is simply a thick E horizon over a Bt horizon. Standard particle size fractionation at whole phi intervals, and particle size analysis of the heavy mineral fraction, indicate that eolian sedimentation is unlikely at five of the six sites. Heavy minerals were analyzed with respect to the sedimentological principle of hydraulic equivalence, which provides clear separation of eolian versus water-laid sediment. Results of particle size analysis suggest that the cover sands are water-laid (probably fluvial) at five of the six sites, which favors the bioturbation process of artifact burial. Heavy mineral analysis corroborates the standard particle size data, indicating that only one site, 38CT16, possibly is composed of eolian sediment. Soil profile development suggests that the age of the sediment at site 38CT16 probably is older than 12 ka and was in place prior to human occupation. Therefore, possible eolian sedimentation at that site is not relevant to artifact burial, which also suggests bioturbation is the primary process of artifact burial. Additional evidence favoring bioturbation as a vigorous artifact burial process in the Sandhills comes from the two sites on high elevation sandy fluvial terraces (38CT34, 38CT17) where artifacts are also buried. At these terraced sites bioturbation is the only possible burial process. Overall results suggest that bioturbation best explains the occurrence of buried artifacts and that eolian sedimentation processes are not readily apparent, and are not required, in explaining artifact burial. © 1998 John Wiley & Sons, Inc.     

Erosion of archaeological sites: Results and implications of a site simulation model

A computer simulation model has been developed to investigate the postdepositional changes on archaeological sites due to soil erosion in a semiarid (Mediterranean) environment. Both soil matrix and archaeological artifact movement are accounted for by the model. The model is applied to a series of hypothetical site configurations on hillslopes, using archaeological structures, to observe the morphological changes due to slope form. The results show considerable variation in site preservation potential, relating to different initial spatial patterning of the site and initial slope form. The model predicts thresholds for the start of movement by artifacts, and suggests a correlation between the location of deposition and the potential for disturbance of the artifact record. Implications are drawn from the results of the simulations, both in terms of archaeological theory and practice, and in terms of site conservation and management. The simulation method is recognized as a useful tool for the investigation of natural site formation processes. © 1994 John Wiley & Sons, Inc.     

Shallow site archaeology: Artifact dispersal,stratigraphy, and radiocarbon dating at the Barger Gulch locality B Folsom Site,Middle Park,Colorado

Shallowly buried archaeological sites are particularly susceptible to surface and subsurface disturbance processes. Yet, because cultural deposition often operates on short time scales relative to geologic deposition, vertical artifact distributions can be used to clarify questions of site formation. In particular, patterns in artifact distributions that cannot be explained by occupation histories must be explained by natural processes that have affected sites. Buried only 10–50 cm beneath the ground surface for 10,450 ¹⁴C yr, the Folsom component at Barger Gulch Locality B (Middle Park, Colorado) exhibits many signs of post‐depositional disturbance. Through examination of variation in the vertical distribution of the artifact assemblage, we are able to establish that only a Folsom component is present. Using vertical artifact distributions, stratigraphy, and radiocarbon dating, we are able to reconstruct the series of events that have impacted the site. The Folsom occupation (˜10,450 ¹⁴C yr B.P.) was likely initially buried in a late‐Pleistocene eolian silt loam. Erosion brought the artifacts to rest on a deflation surface at some time prior to 9400 ¹⁴C yr B.P. A mollic epipedon formed in sediments that accumulated between 9400 and 7000 ¹⁴C yr B.P. Some time after 5200 ¹⁴C yr B.P., this soil was partially truncated, and artifacts that had previously dispersed upward created a secondary lag at its upper contact. This surface was buried again and artifact dispersal continued. © 2005 Wiley Periodicals, Inc.     

A micromorphological analysis of stratigraphic integrity and site formation at Cactus Hill,an Early Paleoindian and hypothesized pre‐Clovis occupation in south‐central Virginia,USA

Twenty thin sections were studied from Cactus Hill, a ca. 20 ka stratified sand dune site in Virginia, USA, with a Clovis and hypothesized pre‐Clovis component. The high‐resolution soil micromorphology investigation focused on testing the integrity of Clovis and pre‐Clovis stratigraphy from one location where there is a high density of artifacts. Site formation processes were dominated by eolian (dune) sand formation. There was also ephemeral topsoil development and associated occupation, along with their penecontemporaneous disturbance and dispersal by scavenging animals (assumed) and localized down‐working by small invertebrate mesofauna (as evidenced by aggregates of fine phytolith‐rich humic soil and fine soil‐coated charcoal fragments). Partial erosion of these occupation soils (deflation?) was followed by successive sand burial. Post‐depositional processes affecting these sand‐buried occupations involved only small‐scale bioturbation and overprinting of clay lamellae, suggesting site stratigraphy has been stable for a long time. Soil micromorphological analysis has defined a difference between occupational units (pre‐Clovis and Clovis) and sterile units found between these units as well as above and below. In summary, according to this analysis, the site appears intact with only minor disturbances affecting the long‐term integrity of the stratigraphy. © 2008 Wiley Periodicals, Inc.     

Acheulean artifact accumulation and early hominin land use,Garden Route Casino Road,Pinnacle Point,South Africa

An Early Stone Age Acheulean lithic assemblage collected along a 1.5‐km transect at the Garden Route Casino near Pinnacle Point, Mossel Bay, South Africa, was examined in order to assess the relative degree to which assemblage variability is impacted by post‐occupational processes and/or terrain. It was found that post‐occupational variables do vary across the study area, and they affect the positions of artifacts to different degrees. Terrain structure was determined to have minimal effect on artifact movement. Three analysis sections were identified as having artifacts that were likely close to their original positions and compositions. Future interpretations of differential land use can now be tempered with considerations of the post‐occupational processes that formed the recovered assemblage. © 2009 Wiley Periodicals, Inc.     

多元线性回归分析在车大人沟河泥石流分区与评价中的应用

本文在概述车大人沟河流域泥石流形成的地形地貌、物源和水源等条件的基础上，采用多元线性回归分析方法，选取了物源储量、支沟完整性系数、支沟边坡坡度、支沟沟床比降、冲沟密度、侵蚀模数、不良地质现象和植被覆盖率等八个指标作为自变量，建立与泥石流活跃度间相关关系的数学表达式，计算出车大人沟河40条泥石流支沟活跃度值，从而进行分区评价。将该区泥石流活跃度划分为高、中、低易发区和不发育区，其结果与实地灾情相符，可为车大人沟河流域泥石流防治规划提供科学依据。     

Comparison of sedimentation and occupation histories inside and outside rock shelters,Keep‐River region,northwestern Australia

This paper compares archaeological evidence of Aboriginal occupation inside rock shelters and outside in adjacent sand sheets, focusing on two locations in the Keep‐River region, northwestern Australia. Luminescence and radiocarbon dating reveal that occupation sequences inside rock shelters are generally younger ( < 10,000 yr B.P.) than outside ( < 18,000 yr B.P.). Differences in occupation chronology and artifact assemblages inside and outside rock shelters result from depositional and postdepositional processes and shifts in site function. An increase in regional sedimentation rate from 10 cm/ka ^{− 1} in the Pleistocene to 20 cm/ka ^{− 1} in the Holocene may account for late buildup of sediments within rock shelters, increased artifact accumulation, and reduced postdepositional disturbance in some settings. More intense use of rock shelters in the Late Holocene is indicated from a change in hunting technology and greater production of rock art. The results indicate that some cultural interpretations might be flawed unless archaeological evidence from rock‐shelter and open‐site excavations is integrated. © 2006 Wiley Periodicals, Inc.     

Geologic constraints on the Harappa archaeological site,Punjab Province,Pakistan

The geologic setting of an urban environment affects the development of that particular urban culture. Human activities can involve devegetation, soil loosening, soil‐water and ground‐water changes, soil erosion, and changes in surface‐water hydrology. This article focuses on how the geologic resources and history of the Punjab region have greatly influenced the cultural development of the Bronze Age city of Harappa, located in northeast Pakistan. Archaeological deposits at this site date between at least 3300 B.C. and 1700 B.C. A geologic and geomorphic framework is provided which presents the relationships of the ancient Harappans with their local and regional environment, with these geologic processes affecting both the initial settlement and development of this ancient urban center. Buried soil elevation data, mapped soil distributions, and geomorphic models are used to construct an approximation of the preoccupation paleotopography beneath this site. © 2000 John Wiley & Sons, Inc.     

Sedimentation and continental slope processes in the vicinity of an ocean waste‐disposal site,southeastern Tasmania

Digital echo sounding, SeaBeam swath bathymetry data and sediment cores were collected on the continental slope (1500–3700 m water depth) off southeastern Tasmania in order to study sedimentary processes in the vicinity of an ocean disposal site. The new bathymetry data show that the shallower limits of the disposal site are positioned on the seaward edge of a gently dipping (3°) mid‐slope shoulder, between 1200 and 2100 m water depth. The slope below the disposal site is relatively steep (6.5°) and is cut by submarine canyons which lead into the adjacent East Tasman Saddle. The SeaBeam bathymetry data show a small submarine canyon traversing the slope in 2400 m water depth directly downslope from the disposal site, with local slopes of up to 22°. The canyon feeds into a perched basin at 2450 m, which could be acting as a local sediment trap. Short (<90 cm) gravity cores indicate that indurated erosional surfaces characterise the slope environment. The cores contain Upper Cretaceous (upper Campanian) sandstones and siltstones, which in places crop out on the sea floor where they are locally draped by a thin (0–30 cm), modern layer of hemipelagic calcareous ooze. Five cores collected from the vicinity of the disposal site had lead and zinc concentrations in the surface 1 cm of 10.3 ± 5.0 and 39.5 ± 19.6 mg/kg, respectively, significantly greater than the background values (2.9 ± 1.4 for lead and 21.2 ± 5.4 for zinc) which characterise the underlying unit that is composed of the same hemipelagic calcareous ooze. Lead and zinc are constituents of the dumped material, jarosite, which, after mixing with slope sediments, can be used as sediment tracers. One core contains a fining‐upwards bed which is also elevated in lead and zinc. This is interpreted as evidence for dispersal of the jarosite from the disposal site downslope to depths >3000 m via turbidity flows sometime during the past 24 years. Current meter data collected from 30 m above the sea floor over one year at the disposal site show that bottom currents attain speeds of up to 0.46 m/s. The current events are attributed to eddies shed by the East Australia Current. The measured bottom currents are capable of transporting fine‐grained hemipelagic muds and could provide a trigger mechanism for turbidity flows.