Late-Quaternary landscape evolution and geoarchaeology of the Cottonwood River basin, Flint Hills, Kansas.

摘要

The pattern of cultural deposits in a fluvial context is controlled by the temporal and spatial pattern of late-Quaternary landscape evolution. Floodplain deposition, erosion and stability act as geologic filters by destroying, preserving, and modifying the cultural record. This study examines late-Quaternary landscape evolution in the Cottonwood River basin, located in the Flint Hills of eastern Kansas. The objectives of the study were to (1) identify and describe sediments and soils in the Cottonwood River valley and its tributaries, (2) determine radiocarbon ages of valley fills and construct an alluvial chronology for the Cottonwood River system, and (3) develop a predictive model for locating cultural deposits in the river basin. Data indicate that small valleys (third-order) were zones of net sediment storage during the early and late Holocene. Aggradation in large valleys in the early Holocene was punctuated by periods of landscape stability at ca. 10,500 and 8,800 14C yr B.P. Another period of landscape stability is recorded at ca. 2,500 yr B.P. in large valleys. Late-Holocene sediments in the larger valleys dating to the past ca. 4,000 14C yr B.P. grade into younger late-Holocene deposits dating to the past ca. 1,000 14C yr B.P. in the smaller valleys. Few middle-Holocene ages have been recorded in the basin. The entire basin appears to be a zone of net sediment erosion during the middle Holocene. These patterns of erosion, deposition and stability are attributed to major climatic changes during the late Wisconsinan and Holocene. Radiocarbon ages and alluvial stratigraphic information provide the basis for predicting where buried cultural deposits are likely to occur in the Cottonwood River basin.