UPLAND RELICT PERIGLACIAL LANDFORMS IN SOUTHERN NEW ENGLAND

Relict periglacial landforms dating back to post-glacial permafrost conditions 15,500 to 14,500 years BP have been recognized by many researchers in southern New England. The most commonly discussed example of these landforms are circular, rimmed depressions called pingo, palsa or lithalsa scars, found dominantly within the exposed lake bottom sediments of previous drained glacial lakes. More recently, due to availability high resolution topographic data (LiDAR), similar circular, rimmed depressions have been recognized in upland areas away from drained lake basins and underlain by glacial till. In 2022, we reported on the results of a study focused on one such depression in Massachusetts, with a basal age of 14,530 cal yrs BP. Here, we present the results of another such study in Connecticut, within Owen Mortimer Land Preserve in the Town of Simsbury. We collected 4 sediment cores within circular depressions at this site. Cores were analyzed for organic content (LOI), elemental analysis (pXRF), grain size, and radiocarbon dating. Calibrated radiocarbon dating results from the largest and best example at the site range from 15,070 to 15,480 cal yrs BP, with these age separated by 100 cm - suggesting rapid infilling over this time. Overall, these results are consistent the notion that these landforms are related to permafrost conditions 15,500 to 14,500 years, rather than them being a proglacial feature such a small recessional moraine or ice rampart.