HISTORICAL SEDIMENTATION IN TWO ADIRONDACK LAKES: A MULTIPROXY STUDY

Dimictic freshwater lakes in the Adirondack Park, northern NY, have been used to understand regional effects of Holocene climate and environmental responses. Today the Adirondacks are the largest area of publicly protected land in the contiguous U.S, but prior to its creation in 1892, the region was almost entirely deforested. During the Industrial Revolution, lakes such as Tupper Lake (TL) and Long Lake (LL) were important collection points for lumber headed to sawmills local and distant. And as natural sediment sinks, lakes record paleoenvironmental changes, including those in response to anthropogenic activities. The lakes cored in this study feature prominently in the industrial history of the Adirondacks due to their location on the Raquette River, a large watershed connecting the central highlands to the St. Lawrence River. With the aim of quantifying the effects of the lumber industry over historical time periods, six short cores ranging from 30 to 60 cm were collected in littoral regions of TL and LL. Cores were extruded, split, and described in high resolution, before being sampled for smear slide analysis, total organic carbon, and δ¹³C isotopic measurements of bulk sediment. Cores could not be reliably correlated within each lake due to a high degree of spatial variability in the littoral zone. Micaceous and diatom-rich silty clays dominated TL cores, while the LL record was characterized by distinct sand and mud beds, beds containing abundant wood chips, and significant organic material. From the smear slide analysis, fine sediments were comprised of ~20% intact diatom frustules. Coarser sediments displayed more fragmented diatoms, likely due to post-depositional reworking in a higher energy setting. Carbonates such as authigenic micrite and ostracods were not present. Data generated from the cores was analyzed within the historical context of TL and LL. Evidence of the proximity and impact of local sawmills in the form of macrofragments of wood was observed directly in LL. However, neither basin’s cores contained charcoal beds, which could have tied these records to large historical fire events. Ultimately, this study provides a baseline for anthropogenic impacts on paleoenvironment that can be helpful in distinguishing local paleoenvironmental changes from regional or global paleoclimatic ones.