Rolfe D. Mandel

Holocene environments of the central Great Plains: multi-proxy evidence from alluvial sequences, southeastern Nebraska

Abstract Pollen, plant macrofossils, phytoliths, carbon isotopes, and alluvial history from sediments exposed along the South Fork of the Big Nemaha River, southeastern Nebraska, USA, provide an integrated reconstruction of changes in Holocene vegetation, climate, and fluvial activity. From 9000 to 8500 uncalibrated 14 C yr BP, climate became more arid and the floodplain and alluvial fans in the main valley aggraded rapidly, upland deciduous forest declined, and prairie attained its Holocene dominance. From 8500 to 5800 yr BP. upland forest elements disappeared, and even riparian trees were sparse under dry climatic conditions. Alluvial fans continued to aggrade but aggradation in the main valley was interrupted by a stable episode 7000 yr BP. From 5800 to 3100 yr BP, riparian forests returned to prominence, and droughts were intermittent. Alluviation was slower and punctuated by two major episodes of channel incision and terrace formation in the main valley. Aggradation on alluvial fans slowed and finally ceased near the end of this period. During a short dry interval from 3100 to 2700 yr BP riparian trees (except elm) disappeared, and prairie and weedy species became more abundant. This interval is represented by the organic Roberts Creek Member, and the alluvial setting was a slightly incised meandering channel belt. Habitats became similar to presettlement conditions during the last 2700 yr BP. Weedy taxa dominate modern samples, reflecting widespread disturbance. Alluvial fans and terrace surfaces were stable during the last 2500 years, but episodes of floodplain aggradation were punctuated by incision of the main channel.

Watson Brake, a Middle Archaic mound complex in northeast Louisiana

Middle Archaic earthen mound complexes in the lower Mississippi valley are remote antecedents of the famous but much younger Poverty Point earthworks. Watson Brake is the largest and most complex of these early mound sites. Very extensive coring and stratigraphic studies, aided by 25 radiocarbon dates and six luminescence dates, show that minor earthworks were begun here at ca. 3500 B.C. in association with an oval arrangement of burned rock middens at the edge of a stream terrace. The full extent of the first earthworks is not yet known. Substantial moundraising began ca. 3350 B.C. and continued in stages until some time after 3000 B.C. when the site was abandoned. All 11 mounds and their connecting ridges were occupied between building bursts. Soils formed on some of these temporary surfaces, while lithics, fire-cracked rock, and fired clay/loam objects became scattered throughout the mound fills. Faunal and floral remains from a basal midden indicate all-season occupation, supported by broad-spectrum foraging centered on nuts, fish, and deer. All the overlying fills are so acidic that organics have not survived. The area enclosed by the mounds was kept clean of debris, suggesting its use as ritual space. The reasons why such elaborate activities first occurred here remain elusive. However, some building bursts covary with very well-documented increases in El Niño/Southern Oscillation events. During such rapid increases in ENSO frequencies, rainfall becomes extremely erratic and unpredictable. It may be that early moundraising was a communal response to new stresses of droughts and flooding that created a suddenly more unpredictable food base.

Prehistoric occupation of Late Quaternary landscapes near Kharga Oasis, Western Desert of Egypt

A systematic geoarchaeological survey conducted north of Kharga Oasis in the Western Desert of Egypt recorded all prehistoric sites in eight transects over a total area of 30 km2. The survey focused on the entire range of landscapes along the fringe of the Libyan Plateau, an area previously assumed by researchers to be uninhabitable. Our objective was to determine the distribution and cultural affiliations of prehistoric sites in relation to different geomorphic settings in this hyperarid environment. The results of the survey reveal temporal and spatial patterns in the record of prehistoric occupation. During the Lower Paleolithic, wadis at the foot of the Plateau escarpment attracted people, as did springs on the floor of the Kharga Depression. During Middle Paleolithic pluvials, wadis and springs were occupied by people, but the archaeological record suggests that human occupation shifted towards small depressions, or pans, on the Libyan Plateau, an area considered uninhabitable by previous researchers. Most of the Middle Paleolithic, Terminal Paleolithic, and Neolithic cultural deposits are associated with the pans. Reduced variability in the geomorphic setting of sites during the Terminal Paleolithic/Neolithic compared to the Middle Paleolithic may reflect reduced effective precipitation during the early Holocene. It is likely that monsoonal summer rains of central Africa periodically penetrated at least as far north as Kharga during the Terminal Paleolithic and Neolithic, supplying water to the pans and wadis. Hence, while wadis and many springs became dry during the Pleistocene–Holocene transition (∼10,000 yr B.P.), the pans remained seasonal ponds with sufficient vegetation to attract game and people to a region that was otherwise a desert.

Geoarchaeology of the Akrotiri Aetokremnos rockshelter, Southern Cyprus

Akrotiri Aetokremnos is a collapsed rockshelter on the southern coast of Cyprus. Excavations revealed a 1-m-thick package of sandy deposits preserved beneath massive roof-fall blocks. These deposits contained cultural materials in direct association with extinct pygmy hippopotamus and other fauna. Based on 31 radiocarbon assays, the site was occupied around 10,600 B.P. Four major stratigraphic units were defined, with cultural features and artifacts concentrated in Strata 2 and 4. Most of the sediments that accumulated in the rockshelter are a product of roof fall, disintegration of bedrock (attrition), and wind action. In addition, a small volume of slopewash entered the back of the shelter through solution cavities and is confined to less than 5% of the site. Although some of the strata have been slightly affected by leaching and clay translocation, there is no evidence of soil development in the shelter. The physical and geochemical properties of the strata indicate that the sediments and associated cultural materials rapidly accumulated on the floor of the shelter soon before the roof collapsed and isolated the underlying deposits from subareal weathering and other site-disturbance processes.

Use and Analysis of Soils by Archaeologists and Geoscientists

Archaeologists generally recognize that there is a relationship between cultural deposits and associated soils and landforms. However, their understanding of what a soil is, as well as what soils can reveal about site formation processes, landscape development, and environments of the past varies greatly. Although archaeologists should not be expected to have a complete grasp of pedology, they should be capable of recognizing and interpreting soils in an archaeological context in order to fully comprehend the record of the human past.

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.

Not such a new light: a response to Ammerman and Noller

Abstract Ammerman and Noller (2005) question several aspects of investigations at the early Holocene site of Akrotiri Aetokremnos in Cyprus. Here we address their criticisms, paying particular attention to three ambiguities that they noted. We also suggest that their claim to having discovered contemporary sites may be premature.

Geomorphology and Stratigraphy

Geomorphic investigations were conducted at 13HA385 in 1997, 1998, and 1999 (corresponding with the Phase I-III archaeological investigations). The primary goal of these investigations was to place the sites archaeological record in a geologic context. Soils and stratigraphic units were defined and described, and sedimentary environments were reconstructed. The geomorphic and soil-stratigraphic data provided the basis for interpreting site formation processes at 13HA385. In addition, these data, combined with temporal information gleaned from radiocarbon assays, were used to reconstruct the history of human occupation at 13HA385.

The first occurrence of a toxodont (Mammalia, Notoungulata) in the United States

This is the publishers version, also available electronically from http://www.tandfonline.com/doi/abs/10.1080/02724634.2012.711405#.U1qJK4UvDGJ.

A Middle Archaic burial from east central Kansas

In late 2001, investigators excavated a solitary Middle Archaic burial from the Plains-Prairie border in east-central Kansas. The burial was contained in a dissected colluvial apron at the foot of the valley wall, in a soil horizon that began accumulating around 9000 B.P. Burial goods include deer bone, a drill, and a side-notched projectile point/knife, the morphology of which is consistent with side-notched Middle Archaic points of the North American Central Plains and Midwest. Use-wear analysis shows that the stone tools were used before being placed with the burial and were not manufactured specifically as burial goods. A radiocarbon assay of the deer bone in direct association with the burial yielded a radiocarbon age of 6160 ± 35 B.P. This is one of only a few burials older than 5,000 years in the region. Comparison of this burial to other coeval regional burials shows similarities in burial practices.