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Application of sedimentary-structure interpretation to geoarchaeological investigations in the Colorado River Corridor, Grand Canyon, Arizona, USA

We present a detailed geoarchaeological study of landscape processes that affected prehistoric formation and modern preservation of archaeological sites in three areas of the Colorado River corridor in Grand Canyon, Arizona, USA. The methods used in this case study can be applied to any locality containing unaltered, non-pedogenic sediments and, thus, are particularly relevant to geoarchaeology in arid regions. Resolving the interaction of fluvial, aeolian, and local runoff processes in an arid-land river corridor is important because the archaeological record in arid lands tends to be concentrated along river corridors. This study uses sedimentary structures and particle-size distributions to interpret landscape processes; these methods are commonplace in sedimentology but prove also to be valuable, though less utilized, in geoarchaeology and geomorphology. In this bedrock canyon, the proportion of fluvial sediment generally decreases with distance away from the river as aeolian, slope-wash, colluvial, and debris-flow sediments become more dominant. We describe a new facies consisting of 'flood couplets' that include a lower, fine-grained fluvial component and an upper, coarser, unit that reflects subaerial reworking at the land surface between flood events. Grain-size distributions of strata that lack original sedimentary structures are useful within this river corridor to distinguish aeolian deposits from finer-grained fluvial deposits that pre-date the influence of the upstream Glen Canyon Dam on the Colorado River. Identification of past geomorphic settings is critical for understanding the history and preservation of archaeologically significant areas, and for determining the sensitivity of archaeological sites to dam operations. Most archaeological sites in the areas studied were formed on fluvial deposits, with aeolian deposition acting as an important preservation agent during the past millennium. Therefore, the absence of sediment-rich floods in this regulated river, which formerly deposited large fluvial sandbars from which aeolian sediment was derived, has substantially altered processes by which the prehistoric, inhabited landscape formed, and has also reduced the preservation potential of many significant cultural sites.

Geomorphology

Late quaternary regional geoarchaeology of Southeast Alaska Karst: A progress report

Karst systems, sea caves, and rock shelters within the coastal temperate rain forest of Alaska's Alexander Archipelago preserve important records of regional archaeology, sea level history, glacial and climatic history, and vertebrate paleontology. Two 14C AMS dates on human bone discovered in a remote cave (49-PET-408) on Prince of Wales Island document the oldest reliably dated human in Alaska to ca. 9800 B.P. A series of 14C AMS dates from cave deposits span the past 40,000 years and provide the first evidence of Pleistocene faunas from the northwest coast of North America. Other discoveries include sea caves and marine beach deposits elevated above modern sea level, extensive solution caves, and mammalian remains of species previously undocumented within the region. Records of human activity, including cave art, artifacts, and habitation sites may provide new insights into the early human colonization of the Americas. ??1997 John Wiley & Sons, Inc.

Alaska

Geoarchaeology at Gilman Falls: An Archaic Quarry and Manufacturing Site in Central Maine, U.S.A

Interdisciplinary investigations at the Milford Reservoir, central Maine, resulted in excavation and analysis of a Middle Archaic quarry and manufacturing site at Gilman Falls, dated to between 7300 and 6300 yr B.P. Lithological analysis indicates that the majority of the artifacts came from very local outcrops, providing low-grade metamorphic rocks. Native Americans used a specialized technique to reduce the granofels and other rocks to long rods, artifacts commonly placed in local cemeteries. The Gilman Falls site was largely abandoned once these artifacts were no longer in vogue. Therefore, access to particular bedrock outcrops seems to have played an important role in site selection. Gilman Falls and other early to middle Holocene sites are preserved where bedrock sill dams ponded water that deposited fine sand. Early site sedimentation history is paralleled by a drainage change in the headwaters of the Penobscot River. Evidence for lower mid-Holocene lake levels and a period of higher temperatures and lower precipitation may correlate with the sedimentation history. ?? 2001 John Wiley & Sons, Inc.

Geoarchaeology - An International Journal

Geoarchaeology of stratified paleoindian deposits at the Big Eddy site, Southwest Missouri, U.S.A

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.

Geoarchaeology

Soils and late-Quaternary landscape evolution in the Cottonwood River basin, east-central Kansas: Implications for archaeological research

Temporal and spatial patterns of landscape evolution strongly influence the temporal and spatial patterns of the archaeological record in drainage systems. In this geoarchaeological investigation we took a basin‐wide approach in assessing the soil stratigraphy, lithostratigraphy, and geochronology of alluvial deposits and associated buried soils in the Cottonwood River basin of east‐central Kansas. Patterns of landscape evolution emerge when stratigraphic sequences and radiocarbon chronologies are compared by stream size and landform type. In the valleys of high‐order streams (≥4th order) the Younger Dryas Chronozone (ca. 11,000–10,000 14 C yr B.P.) was characterized by slow aggradation accompanied by pedogenesis, resulting in the development of organic‐rich cumulic soils. Between ca. 10,000 and 4900 14 C yr B.P., aggradation punctuated by soil formation was the dominant process in those valleys. Alluvial fans formed on the margins of high‐order stream valleys during the early and middle Holocene (ca. 9000–5000 14 C yr B.P.) and continued to develop slowly until ca. 3000–2000 14 C yr B.P. The late‐Holocene record of high‐order streams is characterized by episodes of entrenchment, rapid aggradation, and slow aggradation punctuated by soil development. By contrast, the early and middle Holocene (ca. 10,000–5000 14 C yr B.P.) was a period of net erosion in the valleys of low‐order streams. However, during the late Holocene small valleys became zones of net sediment storage. Consideration of the effects of these patterns of landscape evolution on the archaeological record is crucial for accurately interpreting that record and searching for buried archaeological deposits dating to specific cultural periods.

Kansas

Elemental, isotopic, and geochronological variability in Mogollon-Datil volcanic province archaeological obsidian, southwestern USA: Solving issues of intersource discrimination

Solving issues of intersource discrimination in archaeological obsidian is a recurring problem in geoarchaeological investigation, particularly since the number of known sources of archaeological obsidian worldwide has grown nearly exponentially in the last few decades, and the complexity of archaeological questions asked has grown equally so. These two parallel aspects of archaeological investigation have required more exacting understanding of the geological relationship between sources and the more accurate analysis of these sources of archaeological obsidian. This is particularly the case in the North American Southwest where the frequency of archaeological investigation is some of the highest in the world, and the theory and method used to interpret that record has become increasingly nuanced. Here, we attempt to unravel the elemental similarity of archaeological obsidian in the Mogollon-Datil volcanic province of southwestern New Mexico where some of the most important and extensively distributed sources are located and the elemental similarity between the sources is great even though the distance between the sources is large. Uniting elemental, isotopic, and geochronological analyses as an intensive pilot study, we unpack this complexity to provide greater understanding of these important sources of archaeological obsidian.

New Mexico

Paleoenvironmental, epigraphic, and archaeological evidence of total warfare among the Classic Maya

Despite over a century of archaeological research, the nature and broader consequences of Classic Maya warfare remain poorly understood. Based on frequent epigraphic references and iconographic themes, Classic period (250-950 CE) Maya warfare has largely been viewed as ritualized and limited in scope. Evidence of warfare in the Terminal Classic period (TCP, 800-950 CE) is interpreted as an escalation of military tactics that played a role in the socio-economic collapse of the Classic Maya civilization. Implications of specific textual references to war events remain unknown, however, and the paucity of field data precludes our ability to test collapse theories tied to warfare. Here we present geoarchaeological evidence of a large fire event and connect it to a battle described with a Classic period war statement (puluuy), clarifying its meaning and providing insight into the strategies and impacts of Maya warfare. Multiple lines of evidence show that a massive fire occurred across the ancient city of Witzna during the last decade of the 7th century CE, coincident with a written account of Witzna’s burning by the kingdom of Naranjo in 697 CE. Following this event human activity at Witzna declined dramatically, indicating the battle had broad societal impacts. Puluuy is a commonly occurring war statement, and these findings show that the Maya engaged in tactics akin to total warfare earlier and more frequently than previously thought. This research provides insights into the broad societal impacts of Classic period warfare and necessitates a reevaluation of the role of warfare in the Maya collapse.

Nature

Ancient earthquakes from archaeoseismic evidence during the Visigothic and Islamic periods in the archaeological site of “Tolmo de Minateda” (SE Spain)

The ruins of the ancient settlement of “El Tolmo de Minateda” are one of the best representative archaeological sites within the Albacete Province (SE Spain), characterized by a well-preserved record for the last ~3800 yr. The present ruins record an almost continuous of occupation from the Late Bronze Age (Iberian Culture, from ca. third century B.C.) to the High Middle Ages, including intervening and successive Roman, Visigoth, and Muslim city remains. The eventual Muslim settlement was abruptly abandoned and destroyed during the ninth–tenth centuries A.D., leaving a lack of any archaeological evidence of war or decay. Another previous anomalous archaeological episode of abrupt city abandonment and destruction is recorded during the Visigothic Period (seventh century). The archaeological record of this city supports evidence for earthquake damage linked to both periods of city abandonment and destruction, including oriented collapse of walls, watchtowers, and columns, oriented cracking of walls and column drums, as well as in situ broken pottery, abrupt abandonment of kilns, and anomalous sedimentary infilling of canals and water-supply facilities. Additionally, large-scale rockfalls containing Visigothic carved tombs are also apparently associated with both episodes, constituting one of the few instances of combined geoarchaeological evidence of earthquake ground effects ever reported. As a means of testing the theoretical archaeoseismic potential of this site, we obtained an archaeoseismic quality factor (AQF) value of 0.074.

Tolmo de Minateda

Earthquake-induced burial of archaeological sites along the southern Washington coast about A.D. 1700

Although inhabited by thousands of people when first reached by Europeans, the Pacific coast of southern Washington has little recognized evidence of prehistoric human occupation. This apparent contradiction may be explained partly by geologic evidence for coastal submergence during prehistoric earthquakes on the Cascadia subduction zone. Recently discovered archaeological sites, exposed in the banks of two tidal streams, show evidence for earthquake-induced submergence and consequent burial by intertidal mud about A.D. 1700. We surmise that, because of prehistoric earthquakes, other archaeological sites may now lie hidden beneath the surfaces of modern tidelands. Such burial of archaeological sites raises questions about the estimation of prehistoric human population densities along coasts subject to earthquake-induced submergence.

Washington

Use of archaeology to date liquefaction features and seismic events in the New Madrid seismic zone, Central United States

Prehistoric earthquake-induced liquefaction features occur in association with Native American occupation horizons in the New Madrid seismic zone. Age control of these liquefaction features, including sand-blow deposits, sand-blow craters, and sand dikes, can be accomplished by extensive sampling and flotation processing of datable materials as well as archaeobotanical analysis of associated archaeological horizons and pits. This approach increases both the amount of carbon for radiocarbon dating and the precision dating of artifact assemblages. Using this approach, we dated liquefaction features at four sites northwest of Blytheville, Arkansas, and found that at least one significant earthquake occurred in the New Madrid seismic zone between A.D. 1180 and 1400, probably about A.D. 1300 ± 100 yr. In addition, we found three buried sand blows that formed between 3340 B.C. and A.D. 780. In this region where very large to great earthquakes appear to be closely timed, archaeology is helping to develop a paleoearthquake chronology for the New Madrid seismic zone.

Arkansas, Kentucky, Missouri, Tennessee

Early Agriculture in the eastern Grand Canyon of Arizona, USA

Abandoned fields in Colorado River alluvium in the eastern Grand Canyon show signs of primitive agriculture. Presence of maize pollen in association with buried soils near Comanche Creek suggests that farming began prior to 3130 yr B.P. Cotton pollen, identified in buried soils near Nankoweap Creek, dates to 1310 yr B.P., approximately 500 years earlier than previously reported anywhere on the Colorado Plateau. Farming spanned three millennia in this reach of the canyon. Entrenchment, starting approximately 700 yr B.P., making water diversion to fields infeasible, was likely responsible for field abandonment.

Arizona

Mineralogical Approaches to Sourcing Pipes and Figurines from the Eastern Woodlands, U.S.A.

Provenance studies of stone artifacts often rely heavily upon chemical techniques such as neutron activation analysis. However, stone specimens with very similar chemical composition can have different mineralogies (distinctive crystalline structures as well as variations within the same mineral) that are not revealed by multielemental techniques. Because mineralogical techniques are often cheap and usually nondestructive, beginning with mineralogy allows the researcher to gain valuable information and then to be selective about how many samples are submitted for expensive and somewhat destructive chemical analysis, thus conserving both valuable samples and funds. Our University of Illinois team of archaeologists and geologists employs Portable Infrared Mineral Analyzer (PIMA) spectroscopy, X-ray diffraction (XRD), and Sequential acid dissolution/XRD/Inductively coupled plasma (SAD-XRD-ICP) analyses. Two case studies of Hopewellian pipes and Mississippian figurines illustrate this mineralogical approach. The results for both studies identify sources relatively close to the sites where the artifacts were recovered: Sterling, Illinois (rather than Ohio) for the (Hopewell) pipes and Missouri (rather than Arkansas or Oklahoma) for the Cahokia figurines. ?? 2002 Wiley Periodicals, Inc.

Geoarchaeology - An International Journal

The Ryan/Harley site: Sedimentology of an inundated Paleoindian site in north Florida

The Ryan/Harley site (Florida Master Site File Number: 8Je-1004) is a Middle Paleoindian habitation site containing Suwannee points. Based on stratigraphic correlation and diagnostic artifact seriation, Suwannee-age sites have been relatively dated from ??? 10,900 14C yr B.P to ??? 10,500 14C yr B.P. Clovis-like traits on the Suwannee points and other stone tools from the Ryan/Harley site suggest it dates to the earlier end of the Suwannee timeframe. The currently inundated site is partially buried beneath a sediment column located in a swamp forest and partially exposed in a side channel section of the Wacissa River, Jefferson County, Florida. Research done prior to this analysis determined that the artifact assemblage appeared to be unsorted and was contained in a midden-like unit. Our purpose here is to assess the issue of site integrity further. Unconsolidated sediment samples collected from the artifact-bearing horizon and from horizons immediately above and below the artifact horizon were analyzed using granulometric techniques. Arithmetic probability plots of the grain-size distributions show that the sediments were transported and deposited by fluvial processes. Thus, the Suwannee points and associated artifacts, and faunal remains appear to have accumulated during a time of subaerial exposure perhaps after a regional water-table decline, and have remained largely or essentially intact, with little or no postdepositional reworking. The artifacts and faunal remains recovered from the artifact-bearing horizon at Ryan/Harley are distributed randomly, showing no sign of sorting. In the fossil suite, two articulated white-tailed deer (Odocoileus virginianus) vertebra were recovered in situ. The unsorted nature of artifacts and articulated faunal remains that are contained within the fluvially deposited sediments suggests the Suwannee point level of the Ryan/Harley site has remained undisturbed since original deposition. ?? 2006 Wiley Periodicals, Inc.

Geoarchaeology

Late Pleistocene and Early Holocene lake-level fluctuations in the Lahontan Basin, Nevada: Implications for the distribution of archaeological sites

The Great Basin of the western U.S. contains a rich record of late Pleistocene and Holocene lake-level fluctuations as well as an extensive record of human occupation during the same time frame. We compare spatial-temporal relationships between these records in the Lahontan basin to consider whether lake-level fluctuations across the Pleistocene-Holocene transition controlled distribution of archaeological sites. We use the reasonably well-dated archaeological record from caves and rockshelters as well as results from new pedestrian surveys to investigate this problem. Although lake levels probably reached maximum elevations of about 1230-1235 m in the different subbasins of Lahontan during the Younger Dryas (YD) period, the duration that the lakes occupied the highest levels was brief Paleoindian and early Archaic archaeological sites are concentrated on somewhat lower and slightly younger shorelines (???1220-1225 in) that also date from the Younger Dryas period. This study suggests that Paleoindians often concentrated their activities adjacent to large lakes and wetland resources soon after they first entered the Great Basin. ?? 2008 Wiley Periodicals, Inc.

Geoarchaeology

Implications of the fluvial history of the Wacheqsa River for hydrologic engineering and water use at Chavín de Húntar, Peru

Channeling of water through a variety of architectural features represents a significant engineering investment at the first millennium B.C. ceremonial center of Chavín de Huántar in the Peruvian Central Andes. The site contains extensive evidence of the manipulation of water, apparently for diverse purposes. The present configuration of the two local rivers, however, keeps available water approximately 9m below the highest level of water-bearing infrastructure in the site. Geomorphic and archaeological investigation of the fluvial history of the Wacheqsa River has revealed evidence that the Chavín-era configuration of the Wacheqsa River was different. A substantially higher water level, likely the result of a local impoundment of river water caused by a landslide dam, made the provision of water for the hydrologic system within the site a more readily practical possibility. We review what is known of that system and argue that the fluvial history of the Wacheqsa River is critical to understanding this aspect of hydrologic engineering and ritual practice at Chavín. This study demonstrates the relative rapidity and archaeological relevance of landscape change in a dynamic environment.

Chavin de Huantar