EXECUTION HOLLOW AND THE PLAIN: FINDING A KETTLE LAKE ON A KAME TERRACE USING GPR AT WEST POINT, NEW YORK

We designed a survey to collect over 16 acres of Ground Penetrating Radar data to analyze glacial landforms from a large-scale perspective. Using a Sensors & Software LMX200 machine, we collected the data in one 50 foot by 50 foot grid at a time, which translates to over 200 grids. The endeavor will likely take multiple years to finish, but in this project we established a proof of concept and are already able to draw insights from patching together detailed data and viewing it all in a broader context.

The iconic parade grounds of West Point, New York, are referred to colloquially as “The Plain” and are landscaped on a kame terrace depositional feature from deglaciation after the Pleistocene. West Point is situated approximately 50 miles North of New York City, within the Hudson Highlands section of the New England Province. The site is also notable for its role in Revolutionary War history, the longest continuously garrisoned military installation in the United States, and for the last 218 years as home to the United States Military Academy. Very little post glacial modification has shaped the area any further, and much of the small-scale evidence of glacial landforms is often masked by alluvium and Holocene landscaping and development. In particular, a suspected kettle lake on The Plain known as Execution Hollow was infilled in the early 20^th Century for landscaping changes.

In the processed data, we move beyond the easy targets of urban landscapes such as sprinkler systems and utility pipes. When creating depth slices that are hundreds of feet across in both directions, we found that we must adjust our data processing methodology and use different gains and filters for viewing the data at such large scales. Context becomes an important factor, though, and the smaller scale analysis must still be used to ground-truth the big picture data. Mapping glacial features, and potentially validating the existence of the kettle lake, becomes an exercise in holistic understanding and dense data visualization.