TUESDAY DINNER - Co-Hosted with HMPGA
as part of Geology Days 2024

Unglued: The Pleistocene Legacy and Climate Change Future of New York State’s Landscape

Andrew Kozlowski, Ph.D., P.G.,  New York State Geological Survey

Social Hour - 5:30 PM

Dinner - 6:30 PM

Presentation - 7:30 (1 PDH)

Abstract

New field mapping and subsurface investigations by the New York State Geological Survey support previous suggestions that New York State was glaciated multiple times during the Pleistocene. If the climate record preserved in the Greenland Ice Cores and in benthic organisms from marine deposits are comparable, New York State may have experienced as many as 20 glaciations. The erosion and deposition of repeated continental glaciers profoundly impacted the landscape of New York State. The relic glacial landforms in New York and elsewhere in the Great Lakes region archive the geologic processes during a much colder climate. However, prior to the landscape transformation during the Pleistocene the interaction of geologic structure and erosional processes developed drainage patterns on bedrock during the Paleogene and Neogene periods, building a unique physiography of questas and escarpments. Numerous large valley systems encouraged the direction of ice flow during glacial periods until ice sheets thickened and overrode the landscape. Expansive proglacial lakes developed before, during and after glaciation as meltwater became impounded by isostatic depression or ice-dams. Fine-grained sediments deposited in former glacial lake basins can be extensive and exceed 122 meters in thickness. Laminated and rhythmic bedded silt-clay deposits typically have low shear strengths and are commonly prone to failure. At the end of the last glaciation as glaciers retreated and lakes drained, changes in base level resulted in the initiation of modern stream systems.

Incision of streams responding to new base levels at onset of Holocene driven by meteoric waters likely triggered a period of active mass-wasting and landslide activity. However, that landscape eventually established a new equilibrium with Holocene climate and stream systems and hillsides stabilized.

Yet, the past few decades provide clues that perhaps a new climate-equilibrium is underway. More frequent and intense precipitation events strongly suggest that change from a warming climate will result in new landscape adjustments in the coming decades including increased landslides and slope-failures. The stabilized landscape of the Holocene that society has built over will adjust, creating extensive challenges to communities and infrastructure. Professional geologists will play an essential role to map hazard prone areas, educate the public, mitigate slope-failures, and help engineer solutions to a landscape that readjusts to a new climate reality.