Understanding the Subsurface of Garner Run and Bear Meadows through the eyes of Ground Penetrating Radar

Jean Jacques1, Christina Ntim1, Ann Malayil1, Tonian Robinson3,Kristina Keating1, Jorden L. Hayes4, Greg J. Mount5, Angelo Tarzona6, Yonesha Donaldson7, Jael Estrada1, Carolina Caro-Cano1, Roman DiBiase8, Joanmarie Del Vecchio9

Rutgers University-Newark1, Rutgers University-New Brunswick2, University of South Florida College of Arts and Sciences3, Dickinson College4, Resilient Environment Department, Broward County5, Georgia Institute of Technology6, University of Georgia-Athens7,Pennsylvania State University 8, Dartmouth College 9

The Critical zone (CZ) which extends from the top of the vegetation canopy to the free flowing groundwater in the subsurface is believed to support nearly all terrestrial life. Non-invasive Geophysical methods are useful for imaging the critical zone and studying large areas in a short time span. Specifically, methods such as ground penetrating radar, can quantify the depth of soil thickness which can help to understand how the CZ formation and its hydrogeologic processes. In this study we use GPR to determine the structure of the soil layer in the subsurface at two catchments in the Shale Hills Critical Zone Observatory in Pennsylvania: Bear Meadows Forest and Garner Run. Through this research we aim to compare and contrast these two sites which will broaden our understanding of the dynamic processes occurring at the Shale Hills Critical Zone Observatory. Using multiple antenna frequencies, our results indicated that radar wave propagation at the Bear Meadows catchment was limited by ~1 m thick clayey loam on the surface. Garner Run data sets show penetration up to 6 m depth and reveal structural variability. Data collected using GPR indicated both structural and geological differences underneath the study sites. Furthermore, data collected in the Critical Zone Observatories enables the identification of subsurface periglacial features. This research was conducted as part of the 2022 GNOMES program which aims to broaden participation in the geosciences by introducing a diverse group of undergraduate students to critical zone geophysics through a two-week field program.