Eolian processes, ground cover, and the archaeology of coastal dunes: A taphonomic case study from San Miguel Island, California, U.S.A.

Abstract

Geomorphological evidence and historical wind records indicate that eolian processes have heavily influenced San Miguel Island environments for much of the Late Quaternary. The island is almost constantly bombarded by prevailing northwesterly winds, with peak velocities exceeding 75 km/h and wind gusts reaching over 100 km/h. These strong winds played an important role in the location, formation, and preservation of the island's more than 600 archaeological sites. Excavation and surface collection at a stratified Middle and Late Holocene archaeological site on the island's north coast suggest that wind related disturbances result in significant displacement of light fish bones, produce concentrations of shellfish and heavy mammal bones, and cause significant abrasion, etching, and polishing of bones, shells, and artifacts. These data illustrate that wind not only alters surface materials but can significantly disturb subsurface deposits to a depth of at least 20 cm. Working in concert with a variety of taphonomic processes, wind can play a fundamental role in the preservation of archaeological sites and careful scrutiny during excavation and laboratory analysis is required to delineate its effects. (Schä fer, 1972:37).

Wind erosion and intensive prehistoric agriculture: A case study from the Kalaupapa field system, Moloka'i Island, Hawai'i

“…Although recent studies cite wind erosion as a major problem for modern farmers (Sterk, 2003), a key variable effecting nutrient levels in ecosystems (Chadwick et al, 1999;Kurtz et al, 2001;Reynolds et al, 2001;Riksen and De Graaff, 2001;Okin et al, 2004), and a potentially major force impacting archaeological site formation (Rick, 2002), it has received scant consideration in geoarchaeological studies of agricultural development compared with more easily quantifiable environmental costs, such as vegetation change or fluvial erosion (Redman, 1999). Here we analyze the spatial distribution of soil nutrients to document increased wind erosion associated with the transformation of a forested landscape into an intensively cultivated field system on Kalaupapa Peninsula, Moloka'i Island, Hawai'i.…”

Comparing Faunal Remains and Subsistence Technology at CA-SMI-507: A 9,000-Year-Old Paleocoastal Shell Midden on San Miguel Island, California

“…This could be due to deflation, as the high winds that buffet San Miguel Island can abrade bones and remove lighter elements (Rick 2002;Rick et al 2006). No vertebrate remains were observed in intact soil exposures at the site and no teeth or heavier bones-often found on the surface of deflated Late Holocene sites in the area-were found, however, despite the fact that many surface shells appear to be only lightly abraded.…”

Coastal dune hydrology and its influence on maritime occupation sites (12–0.2 ka) in a semiarid island, San Miguel, California, USA

“…Thin weathered late‐Pleistocene dune/loess soils cap the shallow bedrock strata in the interior of the island (Johnson, ; Peterson, Erlandson, et al, ). Reactivations of the shallow dune deposits that cross San Miguel have likely followed episodic devegetation, including widespread vegetation stripping, dune destabilization, and soil erosion associated with historical overgrazing (Johnson, ; Rick, ). Today San Miguel generally lacks perennial lakes or streams (Engle, ), but it likely developed ephemeral freshwater catchments and drainages associated with island’s eolianites, calcium carbonate‐rich dune sand, and associated late‐Pleistocene caliche subsoils (Johnson, , ; Muhs et al, , ; Peterson, Erlandson, et al, ).…”

“…Where they have not been lost to historical erosion from livestock overgrazing and subsequent eolian deflation, these dune deposits protected cultural materials from subaerial weathering and preserved the stratigraphic context and chronology of site occupations. Extensive historical erosion of the dunes (Rick, ) has exposed older soil surfaces and numerous Paleocoastal archaeological sites, where artifacts have been identified and dated from ~12.2 to ~8 ka (Braje, Erlandson, & Rick, ; Erlandson & Braje, ).…”