THE PICTURE EMERGES: LARGE SCALE GPR SURVEYING TO REVEAL BURIED LANDMARKS AND GEOMORPHOLOGY HIDDEN IN PLAIN SIGHT

Approximately 100 years ago, a complete battery complex for two coastal artillery mortars was buried at West Point, New York, when the decision was made to expand the parade field. The mortars are more commonly referred to as “cannons” and are 12-inch diameter, 15-feet long, mounted on carriages that are 92,000 pounds. Normally these would be easy to find with Ground Penetrating Radar (GPR), but the mortars are likely placed just underneath a large set of mounted metal bleachers which are impossible to survey beneath. Historic photos of the complex exist, as well as aerial photos which have been georeferenced to today’s landscaping. Over more than two decades, student-led geophysical investigations have hunted for these artifacts in the subsurface and last year several students finally made strong conclusions to definitively locate the “cannons” in the field. Their renewed methodology took a broader view of the area and took advantage of new GPR capabilities to visualize high resolution depth slices over large areas with relatively quick and easy data collection.

In this study, we continue the work to map the subsurface features of the entire area beyond just the buried 900 square feet structure. The multi-year project requires patching together hundreds of smaller 50 foot by 50 foot grids of processed GPR data to eventually cover an area over 16 acres in size. We hope to reveal the bedrock geomorphology in the area, characterize the suspected kettle lake that was mapped since Revolutionary War times, and expose other glacial features associated with this kame terrace on the banks of the Hudson River. The kame terrace is still recognizable as a glacial depositional feature remaining from Pleistocene deglaciation, and has been preserved in the landscaping that is so iconic to West Point: the parade grounds known as “The Plain.” The suspected kettle lake has a legendary status from recent history and was known as “Execution Hollow” on maps and in stories.