Neal H. Lopinot

The residues of feasting and public ritual at Early Cahokia

Archaeological remains excavated from the stratified layers of a pre-Columbian borrow pit in the middle of the Cahokia site inform our understanding of how ritual events were related to the social and political foundations of that enormous center. Ordinary and extraordinary refuse, ranging from foods and cooking pots to craft-production debris and sumptuary goods, are associated with a series of large-scale, single-event dumping episodes related to activities that occurred in the principal plaza. Taken as a set, the layers of ceramic, lithic, zooarchaeological, archaeobotanical, osteological, paleoentomological, and sedimentological materials reveal that the construction of Cahokias Mississippian order was an active, participatory process.

Evidence for deposition of 10 million tonnes of impact spherules across four continents 12,800 y ago

Significance We present detailed geochemical and morphological analyses of nearly 700 spherules from 18 sites in support of a major cosmic impact at the onset of the Younger Dryas episode (12.8 ka). The impact distributed ∼10 million tonnes of melted spherules over 50 million square kilometers on four continents. Origins of the spherules by volcanism, anthropogenesis, authigenesis, lightning, and meteoritic ablation are rejected on geochemical and morphological grounds. The spherules closely resemble known impact materials derived from surficial sediments melted at temperatures >2,200 °C. The spherules correlate with abundances of associated melt-glass, nanodiamonds, carbon spherules, aciniform carbon, charcoal, and iridium. Airbursts/impacts by a fragmented comet or asteroid have been proposed at the Younger Dryas onset (12.80 ± 0.15 ka) based on identification of an assemblage of impact-related proxies, including microspherules, nanodiamonds, and iridium. Distributed across four continents at the Younger Dryas boundary (YDB), spherule peaks have been independently confirmed in eight studies, but unconfirmed in two others, resulting in continued dispute about their occurrence, distribution, and origin. To further address this dispute and better identify YDB spherules, we present results from one of the largest spherule investigations ever undertaken regarding spherule geochemistry, morphologies, origins, and processes of formation. We investigated 18 sites across North America, Europe, and the Middle East, performing nearly 700 analyses on spherules using energy dispersive X-ray spectroscopy for geochemical analyses and scanning electron microscopy for surface microstructural characterization. Twelve locations rank among the world’s premier end-Pleistocene archaeological sites, where the YDB marks a hiatus in human occupation or major changes in site use. Our results are consistent with melting of sediments to temperatures >2,200 °C by the thermal radiation and air shocks produced by passage of an extraterrestrial object through the atmosphere; they are inconsistent with volcanic, cosmic, anthropogenic, lightning, or authigenic sources. We also produced spherules from wood in the laboratory at >1,730 °C, indicating that impact-related incineration of biomass may have contributed to spherule production. At 12.8 ka, an estimated 10 million tonnes of spherules were distributed across ∼50 million square kilometers, similar to well-known impact strewnfields and consistent with a major cosmic impact event.

Bayesian chronological analyses consistent with synchronous age of 12,835-12,735 Cal B.P. for Younger Dryas boundary on four continents.

Significance A cosmic impact event at ∼12,800 Cal B.P. formed the Younger Dryas boundary (YDB) layer, containing peak abundances in multiple, high-temperature, impact-related proxies, including spherules, melt glass, and nanodiamonds. Bayesian statistical analyses of 354 dates from 23 sedimentary sequences over four continents established a modeled YDB age range of 12,835 Cal B.P. to 12,735 Cal B.P., supporting synchroneity of the YDB layer at high probability (95%). This range overlaps that of a platinum peak recorded in the Greenland Ice Sheet and of the onset of the Younger Dryas climate episode in six key records, suggesting a causal connection between the impact event and the Younger Dryas. Due to its rarity and distinctive characteristics, the YDB layer is proposed as a widespread correlation datum. The Younger Dryas impact hypothesis posits that a cosmic impact across much of the Northern Hemisphere deposited the Younger Dryas boundary (YDB) layer, containing peak abundances in a variable assemblage of proxies, including magnetic and glassy impact-related spherules, high-temperature minerals and melt glass, nanodiamonds, carbon spherules, aciniform carbon, platinum, and osmium. Bayesian chronological modeling was applied to 354 dates from 23 stratigraphic sections in 12 countries on four continents to establish a modeled YDB age range for this event of 12,835–12,735 Cal B.P. at 95% probability. This range overlaps that of a peak in extraterrestrial platinum in the Greenland Ice Sheet and of the earliest age of the Younger Dryas climate episode in six proxy records, suggesting a causal connection between the YDB impact event and the Younger Dryas. Two statistical tests indicate that both modeled and unmodeled ages in the 30 records are consistent with synchronous deposition of the YDB layer within the limits of dating uncertainty (∼100 y). The widespread distribution of the YDB layer suggests that it may serve as a datum layer.

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 f 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. 0 1996 John Wiley & Sons, Inc.

Isotopic evidence for Younger Dryas aridity in the North American midcontinent

Determining the impact of the Younger Dryas (YD) climate event on the unglaciated North American midcontinent has proved difficult due to a scarcity of suitable paleoclimate proxies. Here we present a well-dated carbon isotope (δ13C) record from a buried soil sequence in southwestern Missouri, which reveals a large isotopic excursion during the YD chronozone. In this region of the modern prairie-forest border, the δ13C signature of soil organic matter is a reliable indicator of past climatic change because δ13C values are controlled primarily by the relative abundance of C3 and C4 plants, which is tied to the environmental setting. Between ca. 13,200 and 11,900 yr ago, the abundance of C4 grasses increased by upwards of 50% of the total biomass, indicating expansion of grassland most likely driven by increased aridity during this period. Environmental gradients in the midcontinent must have been very steep, because at the same time that a C4-rich prairie existed in southwestern Missouri, spruce forests grew in Iowa, Illinois, and Ohio.

Trampling experiments in the search for the earliest americans

Experiments were undertaken to evaluate a natural versus cultural origin for a set of modified pebbles and cobbles found in pre-Clovis-age contexts at the Big Eddy site (23CE426) in southwest Missouri, U.S.A. Two experiments involving Asian elephants and American bison provided evidence that pre-Clovis-age modified cobbles, pebbles, and flakes probably were produced by the trampling of large mammals traversing alluvial gravel bars in search of food and water in a riparian environment. The production of “zoofacts” and behavioral aspects of elephants are described with respect to research on the earliest Americans.

The Big Eddy Site: A Multicomponent Paleoindian Site on the Ozark Border, Southwest Missouri

Relatively few deep, stratified, multicompanent Paleoindian sites have been found in alluvial contexts in North America. Recent excavations at the Big Eddy site in southwest Missouri, however, reveal the presence of unique, stratified Paleoindian horizons containing Clovis, Dalton, and San Patrice components. Limited excavations below the Clovis stratum also provide strong evidence for the presence of one or more pre-Clovis horizons. Results of the work at Big Eddy, including discussions of geomorphic contexts, prehistoric components, features, artifacts, and radiocarbon assays, are provided.

The 1997 Excavations at the Big Eddy Site (23CE426) in Southwest Missouri

Abstract : Extensive archaeological and geoarchaeological investigations at the Big Eddy site (23CE426) in the Downstream Stockton easement have documented stratified archaeological deposits extending to at least 4.0 m below surface in the central part of the site. This locality was utilized throughout prehistory, but perhaps most intensively during Late Paleoindian and middle Late Archaic times. The site also contains significant Early Archaic, Early/Middle Paleoindian, and possible pre-Clovis components, and has yielded the first reliable dates associated with a fluted point component in this portion of the midcontinent. Reliable dates also have been obtained for the Late Paleoindian horizon, which lies directly above the fluted-point horizon and contains abundant lithic debris produced by Dalton and San Patrice peoples. Based on sedimentological data, thin-section analysis, refitting studies, microdebitage distribution, and the intact nature of numerous lithic features, the early deposits at the Big Eddy site have very good integrity, Analyses focus on site formation processes and dating, carbon isotopes, an extensive lithic (principally chipped-stone) assemblage, a modest archaeobotanical data set, and limited faunal remains. Given the sites great significance and continued erosion, mitigation should be undertaken as soon as possible.

Implications of Plant Remains from the East Face of Monks Mound

Abstract Flotation-recovered plant remains from a series of 11 sod block samples, 7 features, a limestone concentration, and a mass of organic debris provide insights into the construction of Monks Mound. The presence of uncarbonized seeds exclusively of annuals (other than those of perennial elderberry and wild grape, which probably represent food remains) indicates that the construction of Monks Mound was relatively continuous. The presence of quillwort megaspores and other indicators of wetlands provide additional data on how Monks Mound was constructed and where some borrow and/or sod blocks were likely obtained to construct at least part of this monument.

Ceramic Production and Interaction in the Northern Range of Trinidad

ABSTRACT Regional syntheses based on data recovered mostly from outside of the Northern Range have characterized the mountainous region in northern Trinidad as a boundary between two distinct interaction spheres during the Early Ceramic Age (ca. AD 350–650/800) (Boomert 2000). Changes occurring on Trinidad, other islands of the southern Lesser Antilles, and the South American mainland resulted in the disintegration of these earlier style zones during the final centuries of the Early Ceramic (Boomert 2000, 2010). This period of Late Ceramic cultural realignment was characterized by climate change, the renegotiation of political and social networks, and demographic transformations. We consider newly recovered ceramic evidence from the central Northern Range in order to evaluate the characterization of the region as a boundary and the regions role in broader Caribbean trends. We examine participation in interaction spheres to provide a more nuanced understanding of regional dynamics as they were expressed locally. Ceramic data indicate that occupants of the central Northern Range interpreted regional styles using locally derived materials, thus simultaneously engaging regional traditions and constructing local patterns of resource exploitation.