Click for original image. Click here for the context camera image.
Cool image time! The center of the photo to the right was taken by the high resolution camera on Mars Reconnaissance Orbiter (MRO) on September 5, 2021. For posting here I have rotated, cropped, and reduced it, as well as added to each side the lower resolution context camera image of this region.
The ground slopes downhill to the north. Make sure you click on the image to see the full resolution version. In only a few miles the terrain changes from a mound with small knobs to a smooth area with few knobs to a chaotic area where the larger ridges and knobs are the dominant feature, with hollows and canyons in between.
You should also take a look at the full context camera image. Just to the southeast of the above picture is a large depression that looks like it has been filled with lava, with its western rim covered by that flow. Scientists have taken a lot of high resolution pictures of this depression with MRO, trying to decipher its geology.
The white dot on the overview map to the right shows the location of this photo, on the northwest lower flanks of the giant volcano Arsia Mons. The black dots are all the cool images of pits that I have featured in previous posts on Behind the Black.
This location is in the equatorial regions, so nothing here is likely the result of water ice. Instead, we are looking at the variety of geological shapes the fast moving lava of Mars can take as it covers the ground and solidifies.
As always, something familiar on Earth (lava) behaves on Mars in not quite the same way. We could be looking at the two types of lava that the Hawaiians named pahoehoe for smooth lava and a’a for rough lava, but the scales are different and the Martian lavas are not really the same.
In fact, other than stating these are lava flows that came out of a volcano, it is likely a mistake to think they are the same as Earth lava flows. This is Mars, a different planet with a very different history. We need to recognize that at all times.
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