INTERIOR SEDIMENTARY STRUCTURE OF THE JACKSVILLE ESKER, PENNSYLVANIA
GPR data was acquired using a Mala GPR with a 100MHz antenna set with a trace interval of one centimeter. The data of the interior of the esker was excellent due to the low clay and silt content. Processed data revealed sedimentary layers of varying thicknesses continuously pinching in and out. The data also shows several large entrained boulders along the bottom of the profile with intermixed cobbles throughout.
The data indicates a high energy environment with very little overall organization beyond a group of foreset beds in the North – Western area of the esker. Flow within the esker would have been fluctuating both seasonally and daily. Depending on environmentally controlled conditions the esker beds would have time to set and become more resilient while others would be immediately scoured away with the next high flow. The study shows that the esker has no discernible interior structure and that the sedimentary structure is based on local constraints of available volume for flow, the volume of the flow itself as well as velocity and what is being transported.This study provides insight to the outflow characteristics of a continental size ice sheet immediately at the terminus in regards to outflow and sedimentary load.