A GLACIAL-GEOLOGIC RECORD OF ICE RETREAT IN NORTH-CENTRAL MAINE, USA

The termination of the last ice age (17.8-11.7 ka) provides a unique view into how the global climate system functions during times of rapid warming. Extreme seasonality, with unequal temperature changes in summer and winter, may have been a key feature of abrupt climate changes during the termination in the North Atlantic region. To begin to sort out seasonal variation, we aim to develop a record of summer temperature fluctuations from the glacial-geologic record of north-central Maine. Here, we present the results of glacial-geomorphic mapping and ¹⁰Be exposure ages of glacially transported boulders on moraines, including a newly discovered moraine in the lowlands south of Katahdin. Our preliminary ¹⁰Be dates suggest significant ice-surface lowering 16 – 15 ka, during the latter part of Heinrich Stadial 1 (HS1: 17.8 - 14.7 ka), which may indicate warmer than average summer temperatures during this time. We will discuss the implications of our results with regard to the seasonality hypothesis.