David W. May

Holocene alluvial fills in the South Loup Valley, Nebraska

Abstract Four Holocene alluvial fills are present in Nebraskas South Loup River valley. Fill IV, the oldest and thickest, was deposited between 10,200 and 4800 14 C yr B.P.; Fill III has an age of about 3000 14 C yr B.P.; Fill II is younger than 2100 and older than 900 14 C yr B.P.; and Fill I is younger than 900 14 C yr B.P. Regional contemporaneity of valley alluviation in the eastcentral Great Plains suggests that climate has controlled long-term sediment storage in the South Loup River valley.

LATE HOLOCENE VALLEY-BOTTOM AGGRADATION AND EROSION IN THE SOUTH LOUP RIVER VALLEY, NEBRASKA

Radiocarbon ages of humates, bone collagen, and wood cellulose are used to construct a chronology of valley-bottom aggradation and erosion in the South Loup River Valley in central Nebraska for the past 4800 years. Three episodes of floodplain aggradation are evident from alluvial stratigraphy and radiocarbon ages at four localities. The first episode of aggradation occurred from before 3500 yr B.P. until at least 3000 yr B.P., following deep incision of the valley. The second interval of slow aggradation on the floodplain and soil formation on terraces occurred between 1800 and 1050 yr B.P. A third, rapid episode of valley-bottom aggradation occurred sometime after 1050 yr B.P. Episodes of floodplain erosion during high-magnitude floods occurred before, between, and after these intervals of aggradation. Published radiocarbon ages of peat beds, organic-rich alluvial strata, and buried soils in the North and Middle Loup River Basins reveal that the intervals of aggradation that are documented in the South ...

Site structure and activity organization at a late paleoindian base camp in western nebraska

Paleoindian archaeology on the Great Plains is often characterized by the investigation of large mammal kill/butchery bonebeds with relatively high archaeological visibility. Extensively documented aspects of Paleoindian behavioral variability include the form and composition of weaponry systems, hunting strategies, carcass exploitation, and hunter mobility. Non-hunting oriented aspects of settlement and subsistence behavior are less documented. Information from Component 2 at the O.V. Clary site, in Ash Hollow, western Nebraska, lessens this imbalance of knowledge. It provides a fine-grained, spatially extensive record of Late Paleoindian (Allen Complex) activities at a winter base camp occupied for 5-7 months. This paper highlights elements of site structure and activity organization, emphasizing domestic behaviors including hearth use, site maintenance, and hide working. ArcGIS 9.3.1 (ESRI) and GeoDa 0.9.5-1 (Anselin 2003; Anselin et al. 2006) are employed in conjunction with middle-range observations and expectations to document and interpret spatial patterning in the distribution of over 57,000 artifacts, ecofacts, and red ochre nodules. More broadly, results are related to two models of Paleoindian residential mobility: the place-oriented model and the high-tech forager model. Rather than mutually exclusive scenarios, Component 2 indicates that these models reflect complementary structural poses within the overall behavioral system.

Geospatial Technologies as a Vehicle for Enhancing Graduate Education and Promoting the Value of Geography

Geospatial technologies (GSTs), such as geographic information systems, global positioning systems and remote sensing, present an avenue for expanding the already strong interdisciplinary nature of geography. This paper discusses how GSTs served as a common thread for a crosscutting faculty institute that was established to enhance graduate student teaching and learning at a comprehensive university. Results of this institute demonstrate that this effort advanced graduate education and promoted the value of geographic scholarship across the university.

Properties of a 5500-year-old flood-plain in the Loup River Basin, Nebraska

Abstract Flood-plain aggradation within the Loup River Basin of central Nebraska was episodic and alternated with incision throughout much of the Holocene. A widespread episode of flood-plain stability, however, occurred about 5700–5100 cal. year BP. The purpose of this paper is to describe the properties of this buried flood-plain at six sites in the basin, to consider why the properties of the buried flood-plain vary from site to site, and to evaluate possible reasons why the Loup River flood-plains stabilized 5500 years ago. Episodic valley-bottom aggradation was common during flood-plain formation at five of the six sites. The radiocarbon ages, particle-size data, and organic-carbon data for the buried flood-plain reveal that valley-bottom aggradation generally slowed between about 5700 and 5100 cal. year BP. Erratic down-profile changes in percentages of sand, clay, and organic matter indicate flood-plain sedimentation and soil formation were often episodic. Sand and clay rarely show a steady fining-upward trend. Organic matter fluctuates with depth; at some sites multiple, incipient A horizons were buried during waning valley-bottom aggradation. At two localities, the buried flood-plain is evident as a clay-rich stratum that must have been deposited in a paleochannel. Flood-plain stabilization between 5700 and 5100 cal. year BP probably occurred in response to the effects of external climate forcing on vegetation and hydrologic changes. Flood-plains of other rivers in the central Great Plains also stabilized at this time, further supporting a climatic explanation for slowing of valley aggradation and formation of a flood-plain at this time. Recognition of buried flood-plains is important to both soil mapping in valleys and to the discovery of cultural resources in valleys.

The angus mammoth: A decades-old scientific controversy resolved

The Angus Mammoth site in south-central Nebraska has been controversial since its discovery in 1931 when a fluted artifact was reported to be associated with the mammoth. For nearly 80 years it has not been known if Angus was a paleontological site predating the human occupation of North America as has been asserted by some geologists and paleontologists, or an archaeological site dating to the late Pleistocene as has been advocated by some archaeologists. Geomorphic study and luminescence dating have finally solved the problem after nearly eight decades. Although microwear and technological analyses have determined that the Angus biface is an authentic artifact, TL and IRSL dates have shown that the matrix above the mammoth is much too old for a mammoth/fluted point association to be valid.

Soils and Geomorphology of the Lower Little Cedar River Valley, Northeast Iowa

Few studies exist of the alluvial stratigraphy and geomorphology of the Iowan Surface landform region. We investigated the alluvial stratigraphy, soils, and geomorphology along a section of the lower Little Cedar River to aid in understanding the processes forming this landform region. We used terrace- and floodplain-surface height above the Little Cedar River, soil development, sedimentological characteristics, and stone lines to distinguish alluvial units and landforms. Three Pleistocene surfaces were mapped in the valley, including two terraces and an erosion footslope. The soils and sedimentary characteristics of these surfaces are extremely variable and are used to interpret geomorphic forces acting on the landscape. Holocene alluvial units identified include three terraces and the modern floodplain. Elsewhere in the Midwest, these units have been described as the DeForest Formation, and include the Camp Creek, Roberts Creek, and Gunder Members. The most strongly developed Holocene soils are found within the Gunder Member. Profiles exhibit either A/Bt/C or A/Bw/C horizonation. Soils in Roberts Creek alluvium are not as developed as those in the Gunder Member. These profiles are predominately A/Bw/C. Soil development within Camp Creek alluvium is minimal with A/C profiles.