Stratigraphic Analysis of Paired Vegetated Linear Dunes in the Nebraska Sand Hills Using Ground Penetrating Radar

Keywords: GPR, stratigraphy
Abstract Type: Poster Abstract

Abstract

There are three models of linear dune formation, and there is no agreement on which theory best explains their development. This research focuses on the stratigraphy, the internal sediment layering, of the Nebraska Sand Hills’ paired linear dunes to determine how the dunes there were formed. Sand dunes are given their shape by wind velocity and sand supply. Therefore, the shape of dunes and the internal layering of sediment within them are indicators of the wind regime and dune movements during formation and can be used to determine the correct formation model.

The GPR data was collected in herringbone-shaped transects centered in the trough between two paired linear dunes, extending over the crests. This pattern maximizes the visible internal layering within the dune. Systems and Software’s Pulse EKKO Pro was used for ground penetrating radar (GPR) as a non-invasive, high resolution means of viewing stratigraphy. Topographical data was collected every 2 meters using Topcon RL-H4C laser level. The data was collected using a relatively low frequency of 100 MHz, maximizing image depth while maintaining image resolution. The GPR transmitter and receiver were separated 1 meter apart and traces collected every 0.25 meters. The data collection lines varied from 45 meters to 150 meters long. GPS points were plotted at the beginnings and ends of transects to accurately record GPR data transect locations. Preliminary results show one dune in the pair having stratigraphic layers partially superimposed over the other’s, which could indicate different periods of sand deposition.