Understanding the kinds of activities humans performed in the past is vital, yet it is often difficult for archaeologists to identify activity areas at ephemeral sites. Chemical analysis of soils that have been modified by humans allows archaeologists to identify and understand past activities.

In western Alaska, Liam Frink and Kelly J. Knudson use activity area analysis at modern and archaeological seasonal subsistence occupations to elucidate past lifeways and provide a methodology for investigating ephemeral sites in the archaeological record. They recently completed fieldwork at Tununak on Nelson Island, funded by the National Science Foundation. This work expands upon and complements earlier work on the Yukon-Kuskokwim Delta, where even camps that were occupied for a few weeks have distinct, anthropogenic soil signatures in the slow-forming permafrost soils.