USING MAGNETIC ANOMALIES TO MAP THE DISTRIBUTION OF GLACIAL DEPOSITS IN CENTRAL NEW YORK

Mapping the geographic distribution of glacial deposits in region with little to no exposure and heavy forest cover can be very difficult. Where some glacial deposit landforms can be obvious to identify using topographic maps and digital elevation models, mapping the details of these deposits, or the transition between various depositional environments can be nearly impossible without boreholes. During this investigation, high-resolution magnetic anomaly mapping was conducted between the transition of a drumlin and outwash deposits at the Rice Creek Field Station, Oswego, New York. The objective was to test the magnetic anomaly mapping as a tool to identify the details between the depositional environments. A Cesium vapor walking magnetometer (Geometrics Model G-859) with linked GPS was used to collect more than 40,000 readings within an area of approximately 1 square km over a period of about 5 hours. Additionally, magnetic susceptibility measurements were made on sediment samples in the lab and in the field to use in the final modeling of magnetic anomalies. Overall, the magnetic anomalies associated with the glacial deposits are low. Taking into account the diurnal variation and the total field magnetic field at the time of the survey, the magnetic anomalies are negative overall. The drumlin deposits correspond to a magnetic anomaly that is relatively the highest (-150 nT), with the outwash deposits producing a lower anomaly (--300 nT). The overall negative measurements are probably due to the high quartz content in both deposits. Drumlin deposits having higher overall anomalies suggest that the occurrence of metamorphic and igneous cobbles, boulders and eratics may be significant enough to produce a mappable magnetic contrast.