GROUND PENETRATING RADAR IN SUPPORT OF MASTODON STUDIES IN NEW YORK

Tests of ground penetrating radar (GPR) were carried out at three mastodon sites in New York: the Gilbert site (Chemung Co.), the Hyde Park Site (Dutchess Co.) and the Java Site (Wyoming Co.). The GPR systems used were the Pulse Ekko 100 (Gilbert, Hyde Park) and Noggin 250 (Java) from Sensors and Software. The PE 100 was equipped with 50, 100 and 200 Mhz antennae; the Noggin operates at 250 Mhz. A key issue prior to these surveys was whether radar penetration in the clay rich glacial cover would be adequate to probe depths of interest to paleontology with adequate resolution. The Gilbert site experience provided the most promising results. Because the GPR study was carried out well after excavation was underway, profiling was logistically restricted to flanking areas in the kettle deposits within which the mastodon was found. The survey was implemented by mounting the 100 Mhz GPR antennae on a plastic sled that was then pulled (often floated) over the kettle. The Gilbert GPR profiles are dominated by strong reflections from an interface at depths up to 1.5 m whose subsurface shape (in 3D) mimicked the surface morphology of the kettle. This interface is interpreted to correspond to a clay layer found to overlie the nearby bone bed. GPR with the higher frequency (250 Mhz) Noggin at the Java site achieved lower penetration (ca 0.5 m). However 3D Noggin surveys at the Java site revealed several anomalies that were found to correspond to buried rocks. A short test survey with the sled configuration was carried out across the Hyde Park site before draining. Water bottom and subbottom reflectors were traced at depths approaching 3 m at 100 Mhz (.5 m at 200 Mhz). Unfortunately, equipment malfunctions led to a premature halt at Hyde Park before surveys reached what proved to be the bone locations. Given the lack of data directly over known bones, the efficacy of GPR for direct detection of mastodon remains is still unclear. However, this limited survey experience does confirm that GPR can penetrate to paleontologically significant depths in the glacial materials of northeastern New York, and that GPR represents a practical method of delineating, in 3D, glacial stratigraphy relevant to understanding the geological context of Mastodon deposits.