Click for full image.
Cool image time! The photo to the right, rotated, cropped, and reduced to post here, was taken on May 27, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO), and shows the clash of different layers on the western slope of a mountain within Mars’ largest canyon, Valles Marineris.
The scientist have labeled this a “possible angular unconformity.” In geology an unconformity generally refers to a gap in a series of layers, a period when instead of the layers being deposited they are being eroded away, leaving no record for that time period. An angular unconformity adds tilting to the older layers, which after erosion are then covered by new layers that are oriented somewhat differently.
Based on these definitions, what the scientists suspect is that the brighter layers to the left and lower down the mountain are older. After a period of erosion new layers were deposited on top at a different angle, forming the stripe of layers going from center left up to center right.
The swirly nature of the material on the top of the ridge suggests to me that these layers might be volcanic in nature, but that’s a pure uneducated guess. What some scientists do believe (but have not yet conclusively proven) is that the lower older layers are sediments laid down by an ancient lake that once filled the canyon here.
The overview map below provides a wider view and some context.
The white box marks the location of this image. This particular part of Valles Marineris is also its widest, and is dubbed Melas Chasma.
From this mountain slope the rims of Valles Marineris are a hundred miles away in both directions. The canyon itself is about 29,000 feet deep at this point, which means if placed at the canyon’s bottom the peak of Mount Everest would still be below the rim.
This particular mountain is itself somewhere between 16,000 to 19,000 feet high. If it was in the U.S. it would be among the nation’s highest peaks.
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