Tag: geology

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Cool image time! The picture to the right is taken from a global mosaic created from images taken by the wide-view context camera on Mars Reconnaissance Orbiter (MRO). The original source image was probably a photograph taken on February 15, 2020.

I normally begin with an image from MRO’s high resolution camera, but the only images that camera took of this crater did not show it entirely. This context camera shows it in all its glory, what to my eye appears to be one of the weirdest craters I’ve seen on Mars.

First, note its oblong shape — 5.5 miles long and 3.7 miles wide — which appears to narrow to the southeast. It certainly appears that if this crater was caused by an impact, the bolide came in at a very low angle from the northwest, plowing this 700-foot-deep divot as it drove itself into the ground. Research has shown that an impact has to come in almost sideways to do this. Even at slightly higher angles the resulting craters will still appear round.

But wait, there’s more!
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Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken on September 20, 2025 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

The camera team describes these features as “ridges,” which in one sense is entirely true. The features are ridges that rise above the surrounding plain. The problem is that they are also cracks, with most showing a distinct central fissure in their middle.

Such double ridged cracks are reminiscent of the surface of dried mud or paint, when it begins to crack and shrink. The surface on each side of a crack pulls away, rising upward slightly as it does so. Is that what we are seeing here, the drying of this surface?

As always, location is critical to understanding the Martian geology.
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Cool image time! The picture to the right, rotated, cropped, reduced, and enhanced to post here, was taken on September 24, 2025 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

The science team labels this as an “avalanche scarp”. At first glance it appears we are looking at a major mass wasting event flowing downward to cover the lighter banded terrain near the bottom of the picture.

The problem is that the overlying material didn’t move as an avalanche down onto that lighter material. Note that it has within it its own layers. To have flowed over that lower terrain it would have had to do that coherently, its many layers moving in unison. This doesn’t seem probable, though who knows considering the alien nature of Mars.

So what is going on? And why was this picture taken?
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Cool image time! The picture to the right, cropped to post here, was taken on September 27, 2025 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

The science team labels this “scallop-hosting mantle”. In other words, the surface here has a mantle of material that is for a variety of reason cracking and producing these north-facing scallops. That mantle also appears layered, since it descends downward in terraced steps as you travel north. This particular terrace drops about 40 feet.

Scientists believe [pdf] these scallops are formed in connection with the sublimation of underground ice.

According to [one hypothesis] scallop formation should be ongoing at the present time. Sublimation of interstitial ice could induce a collapse of material, initially as a small pit, then growing southward because of greater solar heating on the southern side. Nearby scallops would coalesce together as can be seen to have occurred.

In the case of the image to the right, this sublimation is also accompanied by a drying process similar to cracks one sees in dried mud. As the ice sublimates away the remain material shrinks and cracks.
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Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken on September 29, 2025 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

The picture shows what the science team labels as a “fringe of perennial ice.” For this picture, north is down. The white stuff on the top half of the image is that perennial ice, while the dark material at the bottom is likely a mixture of dust and debris that is still impregnated with ice.

Mars is a very icy world. Orbital data now suggests that above 30 degrees latitude there is a lot of near surface ice, though it is often mixed in with the red planet’s ample dust, blown there for eons. This location however shows us a place where that ice is on the surface, and is generally pure.

That does not mean however this will be a good location to establish a colony.
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Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken on September 30, 2025 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

The scientists label this image with the term “layers”, but to my eye this is kind of an understatement. The geology in the top half of this picture is more than simply layers, it is an example of that unique Martian geological feature dubbed “brain terrain”, but on steroids.

No one yet knows what causes brain terrain, though scientists think it is related to the sublimation of near surface ice. Normally the tubelike formations are much smaller, only ten to thirty feet long, not hundreds of feet as we see here.

In this case the location of these features makes their formation even more puzzling, as there is no near surface ice found here.
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Cool image time! The picture to the right, cropped to post here, was taken on August 24, 2025 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

The camera team labels this simply as a “terrain sample,” which usually means it was not taken as part of any specific research request, but to fill a gap in the camera’s schedule in order to maintain its proper temperature. When they need to do this, they try to find interesting things to photograph, and mostly succeed.

At first glance the picture to the right does not appear that interesting. If anything it shows an endless expanse of mottled terrain, with no features of any interest at all. This sameness however is what makes this picture and landscape intriguing. What caused it to look this way?
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Cool image time! The picture to the right, cropped and reduced to post here, was taken on August 26, 2025 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). While the full image shows what the camera team labels as the “ridges” that cover this area, the most prominent feature in the whole landscape is this half-mile-wide pedestal crater, sitting about 50 to 100 feet above the surrounding terrain.

What makes this strange butte so weird is the plateau on top, criss-crossed with ridges and hollows in a manner that defies any obvious geological explanation.

Pedestal craters are not uncommon on Mars, and in fact a bunch of others are found throughout this region. The theory for their formation is that they formed when the surface here was much higher. The impact made the crater floor more dense and resistant to erosion, so as the surrounding terrain wore aware the crater ended up being a butte.

However, pedestal craters usually have relatively smooth tops, making this crater another example of a “What the heck?” image.
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Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken on August 26, 2025 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

The camera team labels this “Monitoring New Impact Site.” The fresh impact, indicated by the three dark patches just left and up from center, is actually not that fresh. It was first photographed by MRO on September 27, 2008. This newer picture is to see if anything significant had changed in the subsequent seventeen years.

In comparing the two pictures, the only change that is obvious is that the patches have faded and become less distinct. Nothing else appears different.

The surrounding terrain however is interesting in its own right. The landscape is remarkably flat, though it has that meandering ridge coming out from that lighter patch in the lower right. What are we looking at?
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Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken on August 30, 2025 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

Dubbed a “channel” by the MRO science team, it shows us a meandering canyon with a floor that seems filled with corroded linear features seen frequently on Earth glaciers. Here, the linear ridges appear broken, in many places missing, and in other places so broken their linear nature disappears.

If this was on Earth and I was a global warming activitist, I would immediately claim that the glacier has been evaporating away due to a warming climate caused by SUVs and Republican intransigence. This however is on Mars, where there are no SUVs or Republicans. So what is going on?
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Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken by the high resolution camera on Mars Reconnaissance Orbiter (MRO) and downloaded on August 3, 2025. Labeled as a “terrain sample,” such images are usually taken not as part of any specific research request but because the camera team needs to fill a gap in the camera’s schedule so as to maintain its proper temperature. When they do this, they always try to pick interesting targets within the time window, and usually succeed.

In this case, the camera team picked a location in the middle of Isidis Planitia, one of Mars’ four biggest basins thought to have been formed from a major impact several billion years ago, focusing on an area covered with these strange knobs that have craterlike depressions at their peaks.

According research published in 2010 [pdf], it is believed these cones — all of which are only a few feet high — are the result of volcanic activity following the impact that formed Isidis four billion years ago. In a sense, they are leftover pimples from that impact and the subsequent volcanic activity within that melted basin.
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Cool image time! The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on August 4, 2025 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

The science team labels this a “concentric fill crater,” a term used by planetary scientists for Martian craters that appear to be filled with glacial material. That certainly appears to be the case, but this 3.5-mile-wide unnamed crater also appears to have been warped by the ice that impregnates the ground all around it.

The overview map above explains why. The white dot marks the location, on the eastern end of the 2,000-mile-long northern mid-latitude strip that I label glacier country, because almost every image in this region shows similar glacial features. Though it is hard to tell from the inset, all the craters here have similar glacial material within them, and the ground surrounding them also appears glacial in nature.

This particular location is at 40 degrees north latitude. While it might be difficult to establish a colony here, on ground that appears so unstable, going 700 to 800 miles to the southeast would put you in what is considered one of Mars’ prime mining regions. Thus, with the right equipment mining operations would have accessible water not that far away.

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Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken on June 23, 2025 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). This one-mile-wide unnamed crater was a featured image last week by the science team. As noted in the caption, written by Chris Okubo of the U.S. Geological Survey:

This area was covered by a large flood of lava, which we see as the generally flat areas surrounding the crater. As the lava flowed across, some of it flowed into this crater through a low spot along the crater rim.

Once in the crater, the lava heated ground water or ground ice in the floor, causing the water to boil and turn into steam. This steam then exploded through the overlying lava and created small, ring-shaped formations. These are called ”rootless cones,” and they record the presence of ground water or ground ice in the crater floor at the time of the lava eruptions.

In other words, when this crater was flooded with hot lava, it was filled with ice or water. That fact is significant because of the crater’s location, as shown in the overview map below.
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