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Cool image time! The photo to the right, cropped and reduced to post here, was taken on April 9, 2022v by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows a series of parallel zig-zag ridges in a flat, knobby terrain.

I don’t presume to explain this at all. According to one research paper,

This interplana region consists of extensive networks of ridges—the eponymous Aeolis Dorsa—and is interpreted as having formed by topographic inversion of fluvial and alluvial deposits.

Why these ridges zig-zag however does not seem to fit into either a fluvial or alluvial explanation, both of which involve the flow of water. The quote implies these could be inverted stream channels (where the compacted streambed becomes a ridge when the surrounding terrain erodes away), but once again, the distinct zig-zag pattern seems wrong. Rivers meander, but they don’t generally turn right and left so sharply. And why should we see parallel zig-zags? This doesn’t seem to fit with a river channel origin.

The particular location, as shown on the overview map below, is close to the dry Martian equator, on the edge of Medusae Fossae Formation, the largest field of volcanic ash dust on Mars.

The white dot about 500 miles to the east of Curiosity marks the location of these zig-zag ridges. The proximity of Medusae, with its vast supply of dust, makes me wonder if we are looking at some form of dune, now hardened and eroded many eons after its formation.

This is however a guess, and should not be taken at all seriously. The suggestion in the science paper above is far more likely. For example, if these are inverted river channels, erosion over eons could have caused the meanders to sharpen into these abrupt turns.

Then again, I remain skeptical. I wonder also if we are looking at extrusions through faults, caused by volcanic activity.

Ah, the wonder of the universe. It is so much fun to attempt to untangle its mysteries.