Multi-proxy paleoenvironmental data from Paulina Marsh inform human-environmental dynamics in the Northern Great Basin U.S.A.

Understanding the dynamics between climate change and human adaptive strategies is a longstanding question driving paleoecological and archaeological research in North America's Great Basin. We present multiproxy data from five sediment cores retrieved from Paulina Marsh in the Fort Rock Basin, Oregon, an area renowned for its archaeology but lacking the paleoenvironmental data needed to fully contextualize those records. Radiocarbon, pollen, particle size, elemental, and charcoal analyses of one core, and geochronological data from four additional cores, reveal fluctuating vegetation communities, hydrologic conditions, and fire histories during the Early and Late Holocene that are consistent with models proposed to explain changing settlement-subsistence patterns in the region. There was likely an emergent marsh or meadow and an absence of Juniperus at the core site during the Early Holocene. Middle Holocene deposits are not present due to a geologic unconformity, perhaps because of channel migration and climatic aridity. Late Holocene sediments record a more mesic meandering stream system between ∼3900 and 2200 years ago, followed by an increase in xeric-adapted vegetation in the last 2000 years. The lack of Juniperus pollen in the Early Holocene sediments inform ongoing debates about Juniperus spread in the Great Basin. These data represent the first Early Holocene pollen record from the Fort Rock Basin and are one of few lowland vegetation histories of this age in the region. This study contributes to our understanding of past ecology in semi-arid environments, provides new context for archaeological interpretations, and establishes a framework for future work in the region.