Reull Valles – Behind The Black

Brain terrain in and around pedestal crater on Mars

May 16, 2023 1:13 pm Robert Zimmerman

Click for original image.

Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken on March 10, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

As I noted in a cool image only two weeks ago, brain terrain is a geological feature wholly unique to Mars that planetary geologists still do not understand or can explain. They know its knobby interweaving nodules (resembling the convolutions of the human brain) are related to near surface ice and its sublimation into gas, but no one has much confidence in any of the theories that posit the process that forms it.

In this case the brain terrain not only fills the crater, it appears to surround it as well, but only appearing at spots where a smooth top layer has begun to break apart. Moreover, the crater appears to be a pedestal crater, whereby much of the less dense surrounding terrain has vanished, leaving the compacted crater sitting higher.
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Eroding glacial ice on Mars, dipping in the wrong direction

August 25, 2022 1:00 pm Robert Zimmerman

Click for full image.

Today’s cool image is a variation of a similar phenomenon shown in a cool image I posted in July, dipping terraced layers stepping downhill toward a cliff face, rather than away from the cliff as you would expect. That previous example was located in chaos region in the northern mid-latitudes that I dub glacier country.

This example is instead found a completely different region of Mars, halfway across the planet. The photo to the right, cropped, reduced, and annotated to post here, was taken on March 1, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). The arrows indicate the downward trend of those dipping layers, toward the cliff face.

The overview map below provides the context.
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The icy Reull Valley of Mars

April 25, 2022 12:33 pm Robert Zimmerman

Click for full image.

Cool image time! The photo to the right, cropped and reduced to post here, was taken on February 20, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows the eroded floor of a 10-mile-wide very obscured unnamed crater that sits above the northern wall of a canyon dubbed Reull Valles.

For reference the interior slope of the crater’s southern rim is labelled. The crater sits at 40 degrees south latitude. Thus, this crater is inside the 30 to 60 degree mid-latitude bands where scientists have found many glaciers on Mars. The eroded floor of this crater appears to confirm this conclusion. In the full photo the erosion is even more pronounced, as well as more chaotic, farther from that rim to the north.

Because Reull Valles sits inside that southern glacial band, it is home to much evidence of ice. The overview map below provides the context.
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A river valley floor on Mars

February 18, 2019 12:50 pm Robert Zimmerman

Overview of Reull Valles region

Today’s cool image focuses in on a Mars Reconnaissance Orbiter (MRO) uncaptioned photograph taken of the valley floor of Reull Vallis, a meandering canyon that drains into Hellas Basin, the bottom of Mars.

The image on the right is not that photograph. Instead, it is an overview of the area surrounding it. The image location is indicated by the black cross, dead center within the floor of Reull Vallis itself. This valley, as well as Dao and Niger to the northwest but lower in elevation are all thought to have been formed from flowing water, all of which apparently drained from the east and to the west into Hellas Basin.

This last detail is very important and bears repeating before looking at today’s subject image. The river that formed Reull Vallis flowed from the east to the west. Now for that picture.
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