The micromorphology of loess‐paleosol sequences in central Alaska: A new perspective on soil formation and landscape evolution since the Late Glacial period (c. 16,000 cal yr BP to present)

The middle Tanana Valley of central Alaska contains a well‐preserved record of human occupation and paleoenvironmental change since the Late Glacial period (c. 16,000 cal yr BP) and is a critical region for understanding human dispersal into the Americas. Micromorphology analysis of soils and sedime...

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Bibliographic Details
Published in:Geoarchaeology 2020-09, Vol.35 (5), p.701-728
Main Authors: Kielhofer, Jennifer, Miller, Christopher, Reuther, Joshua, Holmes, Charles, Potter, Ben, Lanoë, François, Esdale, Julie, Crass, Barbara
Format: Article
Language:English
Subjects:
Archaeological sites
Bioturbation
central Alaska
Dispersal
Heterogeneity
Holocene
Humification
Late Pleistocene
Latitude
loess‐paleosol stratigraphy
micromorphology
Organic matter
Soil formation
Soils
Stratigraphy
subarctic
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Summary:The middle Tanana Valley of central Alaska contains a well‐preserved record of human occupation and paleoenvironmental change since the Late Glacial period (c. 16,000 cal yr BP) and is a critical region for understanding human dispersal into the Americas. Micromorphology analysis of soils and sediments from six archaeological sites yields valuable information about soil formation processes and landscape evolution during the Late Glacial and into the Holocene. At the macroscale, site stratigraphies are very similar, and thin organic‐rich layers (locally known as “stringers”) are commonly interpreted as buried soils. However, at the microscale, these layers exhibit significant differences in the degree of bioturbation, organic matter humification, and boundary abruptness, indicating that pedogenesis was not the sole process at every site. In this way, our microscale analysis addresses issues of equifinality related to site formation interpretations, a persistent problem with subarctic and high‐latitude stratigraphy. Additionally, this study reveals a certain level of landform and landscape instability within a broader trend of regional increases in pedogenesis and vegetation coverage, adding to the existing model of heterogeneity across this subarctic landscape. Here we demonstrate the utility of micromorphology to test field interpretations and improve models of Late Glacial landscape evolution in high‐latitude contexts.
ISSN:0883-6353
1520-6548
DOI:10.1002/gea.21807