This image suggestion outlines a contact between gypsum-rich dunes in Olympia Undae and flat-lying layers of the basal (or bottom) unit.
Our goal is to look for a stratigraphic and compositional comparison between the dunes and the basal unit.

ID: ESP_070833_2605
date: 5 September 2021
altitude: 316 km

https://uahirise.org/hipod/ESP_070833_2605
NASA/JPL-Caltech/UArizona