Gullies lying on the northeast slopes of Triolet Crater (about 11.6 km in diameter ), are located in the Southern Highlands just east of Gorgonum Chaos. Some gullies have eroded through resistant layers up to the crater rim.

At the downslope are fans of debris that overlap with those of nearby gully systems, suggesting that there were multiple periods of gully activity in this region. Just south of the gullies is a large fracture that cuts through the crater rim. This fracture is part of the Sirenum Fossae system that slices across the region for over 1,000 kilometers from the northeast to the southwest.

Because this fracture (or “fossae”) cuts through the rim and ejecta blanket of Triolet Crater, this means that the crater is older than the fracture. This is known as a cross-cutting relationship and demonstrates a basic principle in geology known as the “law of superposition.”

Written by: Ginny Gulick (narration: Tre Gibbs)  (24 January 2023)

This is a stereo pair with ESP_075675_1425.