Deposition and pedogenesis of periglacial sediments and buried soils at the Serpentine Hot Springs archaeological site, Seward Peninsula, AK

Abstract

Soil micromorphology is an excellent tool for relating quantitative laboratory data to soil development in complex pedogenic settings. This study utilizes micromorphology, scanning electron microscopy, bulk soil geochemistry, clay mineralogy, and particle-size analysis to reconstruct the depositional and pedogenic history of the Serpentine Hot Springs fluted point site on the Seward Peninsula, Alaska. Sediment deposition occurred via colluviation, which dominated during the late glacial period and early- to middle-Holocene, and aeolian processes, which dominated during the Younger Dryas (YD) and late Holocene. Two buried soils are present: one dating to the Holocene Thermal Maximum (HTM) and the other dating just before the Neoglacial period. Pedofeatures fall into four categories: 1) cryogenic features; 2) clay illuviation features; 3) podzolization/redox features; and 4) anthropogenic features. The spatial relationships among these features provides insight into the pedogenic history of the soil. The HTM soil is characterized by clay illuviation, suggesting warm, mildly acidic, well-drained soil conditions. The pre-Neoglacial soil is characterized by incipient placic horizon development and podzolization, indicative of moist, acidic, variably drained conditions. Cryogenic features associated with late Holocene Neoglaciation dominate the modern soil. Despite cryogenic activity and the presence of permafrost, the cultural stratigraphy of the site remains intact.