Tag: geology

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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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Cool image time! The picture to the right, cropped, reduced, and enhanced to post here, was taken on May 31, 2025 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

The camera team label this “patterned ground.” And it is indeed. Though the topography is almost flat for large distances, the ground itself has these various patterns on it, from meandering small ridges to stippled roughness to very smooth sections.

The location is at 4.6 degrees north latitude, in the dry equatorial regions of Mars. No near surface ice created these features. All we can deduce from this picture is that this landscape is relatively young, as there are no craters seen.

So what caused these features? The location as always provides a clue.
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Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken on June 29, 2025 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It falls into what I call my “What the heck?!” category of Martian land-forms, simply because their shape is so strange and inexplicable it is difficult to conceive a geological process that could create them.

Nor does it help much that we know what these land-forms are made of. The white dot on the overview map above marks the location, inside the 2,000-mile-wide northern mid-latitude strip I label glacier country, because almost every image taken shows glacial features. In this case, this strange geology is located on the floor of a canyon that is part of a large region of chaos terrain, a landscape typical of glacier country. This floor, as well as all the low areas, seems filled with glacial flows. This particular canyon appears to roughly flow downhill to the northwest, though the downhill grade in the entire region varies widely in all directions.

Based on all the orbital data, these flows are glacial in nature, the ice protected by a thin top layer of dirt and debris. The strange features at the top of all the small mesas in the picture above suggest that the wind possibly blew off the dirt and debris, exposing the ice and allowing it to sublimate away. This in turn produced the knobby hollows at the top of each mesa.

I am guessing, and no one should trust my guess considering I only make believe I’m a geologist on the internet.

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In honor of our just completed visit to the south rim of the Grand Canyon, today’s cool image takes us to another location on Mars that to me appears a perfect place to install some hiking trails. The picture to the right, cropped, reduced, and sharpened to post here, was taken on June 30, 2025 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

The image shows a two-mile wide canyon with a number of scattered narrow mesas within. The north and south rims rise about 550 feet above the canyon floor. The two mesas labeled “A” and “B” rise about 200 and 100 feet respectively.

The hiker in me immediately imagines what a great hike it would be to go up the western nose of either ridge and walk along its crest. The knife-edge nature of ridge “A” would mean that for a large majority of the hike you’d be at the north and south edges at the same time.
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Today’s cool image returns to the Martian north pole. The picture to the right, rotated, cropped, reduced, and enhanced to post here, was taken on July 3, 2025 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows the top of a ridge near the edge of that icecap, with dunes visible in the hollow several thousand feet below.

The angle of this picture does not show us the many layers on the cliff leading down to those dunes. It does show evidence, however, of the top few layers on the flat crest of that ridge. The white lines delineate those layers, each line marking the edge of a series of wide terraces.

The dunes in the canyon below are of interest because their source is likely the dust that is mixed into thick icecap’s ice. As that ice sublimates away on the face of the cliff, the dust falls into the canyon, where it is trapped.
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Cool image time! The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on July 1, 2025 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

The science team labels it clumsily as “North Polar layered deposits structural geology in icy layers”. What we see are the many layers that make up the north polar cap, produced by the red planet’s many climate cycles that scientists think Mars has undergone over the eons as the red planet’s rotational tilt, or obliquity, rocked back and forth from 11 degrees inclination to as much as 60 degrees. At the extremes, the ice cap was either growing or shrinking, while today (at 25 degrees inclination) it appears to be in a steady state.

These layers are a mixture of ice and dust. The variations from dark to light likely indicate changes in the amount of dust in the atmosphere. Dark layers suggest the atmosphere was more dusty due to volcanic eruptions. Light layers suggest the planet’s volcanic activity was more subdued.

At least that’s one hypothesis.
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Cool image time! The picture to the right, cropped and sharpened to post here, was taken on July 2, 2025 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

Labeled simply as “wavy terrain” by the MRO science team, it shows a relatively flat plain of hollows and terraced ridges that suggest the prevailing winds come from the west-southwest. As they blow, they slowly cause the layers of material to peel away, exposing those terraces.

This wavy landscape extends for many miles to the west, covering a region 135 by 160 miles in area. The layering and wavy nature of the terrain suggests the material here is fragile and easily peeled away by the winds of Mars’ very thin atmosphere. Think of the sandstone that forms Monument Valley and Canyonlands in the southwest United States, shaped almost entirely by wind.

And in fact, the overview map below confirms this.
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