Bouncing Boulders Point to Quakes on Mars

A preponderance of boulder tracks on the red planet may be evidence of recent seismic activity.

If a rock falls on Mars, and no one is there to see it, does it leave a trace? Yes, and it’s a beautiful herringbone-like pattern, new research reveals. Scientists have now spotted thousands of tracks on the red planet created by tumbling boulders. Delicate chevron-shaped piles of Martian dust and sand frame the tracks, the team showed, and most fade over the course of a few years.

Rockfalls have been spotted elsewhere in the solar system, including on the moon and even a comet. But a big open question is the timing of these processes on other worlds — are they ongoing or did they predominantly occur in the past?

A study of these ephemeral features on Mars, published last month in Geophysical Research Letters, says that such boulder tracks can be used to pinpoint recent seismic activity on the red planet. This new evidence that Mars is a dynamic world runs contrary to the notion that all of the planet’s exciting geology happened much earlier, said Ingrid Daubar, a planetary scientist at Brown University who was not involved in the study. “For a long time, we thought that Mars was this cold, dead planet.”