Late Quaternary landscape history and geoarchaeology of two drainages on Black Mesa, northeastern Arizona, USA

Two approximately 5- to 6-km drainage segments on Black Mesa preserve unusually complete sequences of late Quaternary alluvium and soils. Radiocarbon- and tree-ring-dated alluvial and soil stratigraphy suggests entrenched paleoarroyos were beginning to aggrade at about >24,260, 11,070, 9660, 8800, 7060, 3500, 2140, and 1870 C-14 yr B.P. Using the quantity of sediment removal from post-A.D. 1900 arroyos as analogue, at least 77-200% of total valley alluvium has been removed and replaced by younger sediments during an estimated 11 late Pleistocene and Holocene erosion epicycles. Given that most (59%) of the 150 recorded prehistoric sites in the two study areas occur on valley floors where only about 3% of surface alluvium predates Lolomai phase Basketmaker II occupation (similar to1900-1600 yr B.P.), it may be inferred that pre-Lolomai phase Basketmaker II sites which may have been located along washes have been removed or buried by fluvial erosion. Identification of five buried hearths in alluvial sections, including White Dog and Lolomai phase Basketmaker II sites (dating about 3500 and 1870 C-14 yr B.P., respectively) and one possible Early Archaic site, supports this conclusion. (C) 2005 Wiley Periodicals, Inc.