Tag: geology

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It is time for two cool images! The picture to the right, cropped, reduced, and sharpened to post here, was taken on May 10, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO), and is one of two glaciers imaged by MRO in May that are among a whole series of glaciers flowing down the south wall of the same mesa.

The red dot in the inset and on the overview map above marks the location of the picture to the right. The white dot marks the location of the May 27, 2023 picture, which can be seen here.

The unnamed 10,000-foot-high mesa from which these glaciers flow, located in the middle of the 2,000-mile-long northern mid-latitude strip I dub glacier glacier country, is about 41 miles long and 18 miles wide at its widest point. The glacier to the right falls about 6,000 feet in about four miles, making the grade steep, ranging from 15 to 23 degrees. That steepness explains the split in the glacier, as it flowed around a huge piece of higher bedrock in the middle of this descending hollow.

Both images provide further evidence of the dominance of glaciers in this mid-latitude region. While the glaciers are all covered with dust and debris to protect the ice, and are also thought at present to all be inactive, they also all suggest a very dynamic Martian geological and climate history, one that will likely come alive again as the planet’s rotational tilt naturally shifts back and forth from its present 25 degree tilt to 11 to 60 degrees.

The glaciers also show us again that Mars is not a dry desert, but above 30 degrees latitude it is an icy desert much like Antarctica. Colonists will have no trouble finding water.

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Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken on March 31, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

In labeling this picture the science team focused on the many layers visible in these swirls, all suggesting a series of cyclical events, each laying down a new layer over many eons.

What caused the swirls? Looking at the lower right quadrant it appears that they were glacial, with the flow to the northwest but with each glacial layer smaller and not reaching as far.

This theory falls apart however at the curved depression, which instead suggests the swirl was traveling along a meandering canyon, going from the lower left to the upper right. If so, the curved depression is even more baffling. If ice it could have sublimated away, but its sharp edges suggest this isn’t ice but maybe a lava flow.
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Cool image time! The picture to the right, cropped and reduced to post here, was taken on May 25, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). The scientists describe these cones as “longitudinally aligned cones,” but this is puzzling since the alignment runs from the northwest to the south east, not north-south along the longitude.

No matter. The alignment is in itself the mystery, especially because the full image shows many more strings of cones in this area, all running from the northwest to the southeast. The strings also are all curved in the same way, sagging to the southwest as if expressing a wave flowing in that direction.

What could create these strings of cones? The overview map below gives us a hint.
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Today’s cool image illustrates the once violent and active volcanic past of Mars, now long dormant. The picture to the right, cropped, reduced, and sharpened to post here, was taken on May 11, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows what the scientists label as a “vent and channel” located high on the northeast flanks of the giant volcano Arsia Mons.

The rim around the vent suggests that lava had once bubbled up out of the vent and hardened around it, as most of the lava flowed downhill along the channel. And though this vent appears to be the source of this channel, it is not. The channel continues to the southwest uphill until it reaches the edge of Arsia Mons’ caldera, a region where there are many such vents, many much larger and deeper than this one.
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Cool image time! The picture to the right, rotated, cropped, rotated, and sharpened to post here, was taken on June 3, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows the eastern half of a six-mile-wide unnamed crater with a depth of about 1,500 to 2,000 feet from rim to floor.

What makes this picture significant is the patchy material in the center of that crater floor, some of which looks almost like very old peeling paint. It also resembles the kind of glacial features routinely seen in many craters poleward of 30 degrees latitude on Mars.

Is this another example of such glacial features? If so, its location is what makes it significant.
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Cool image time! The picture to the right, rotated, cropped, and reduced to post here, was taken on April 18, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows only one of many flat-topped mesas in a chaos terrain region dubbed Oxia Chaos.

The mesa top is about 540 feet above the floor of the canyon to the north, which in turn is about 840 feet below the flat terrain north of it. That flat terrain to the north is not part of the chaos terrain, however, but the northern rim of the plateau that surrounds the chaos. Moreover, this particular piece of rim is separating from the plateau, as shown near the top of this January 16, 2008 context camera image from MRO. At some point in the future it will break off and fall into that canyon and on top of this mesa.
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Cool image time! The picture to the right, cropped and reduced to post here, was taken on April 30, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows the rim of a seventeen-mile wide crater, and was the scientists label a “gully without apron,” meaning that though something has caused material to disappear within that gully, beginning high on the rim wall, there does not appear to be any piled up apron or debris at the gully’s base.

The blue colors imply the possibility of frost within the gully, while the orange suggests dust or coarse surface material.

The cracks emanating away at right angles from the gully’s base suggest glacial ice, which makes sense based on the location.
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In looking through new images from Mars Reconnaissance Orbiter (MRO), I sometimes stumble some very strange things, with today’s cool image an example. The picture to the right, rotated, cropped, and reduced to post here, was taken on May 7, 2023 by MRO’s high resolution camera, and shows the western half of a two-mile-wide crater with a very weird rim, almost as if a person had decided he wanted to reshape it with a filigree pattern.

Though only two-miles wide, this crater actually has been named Johnstown. I suspect this is because of its strange rim, prompting a research effort and the need to provide it a name. Why the rim has this repeating pattern of gaps, however, is beyond my pay grade to explain, and I have been unable to track down any research papers about it. The nearby surrounding surface suggests vaguely the possibility that this is a caldera, not an impact crater, but even so why would the rim of the caldera have these regular breaks?
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Today’s cool image takes us to one of Mars’ biggest canyon systems that while linked to Valles Marineris, the biggest Martian canyon of them all, is considered a separate canyon system because it is made up of a labyrinth of criss-crossing canyons instead of a single major canyon line.

In fact, its name is Noctis Labyrinthus, as shown on the overview map to the right. In many ways its complex pattern is reminiscent of the chaos terrain seen mostly in Mars’ mid-latitudes, but there are major differences. The rectangle marks the area we shall zoom into below to show these differences as well as to feebly illustrate the grand scale of these canyons.

First, the formation of these canyons is closely linked to the volcanic events that formed the three giant volcanoes to the west. They are also strongly linked (in ways not yet fully understood) with the suspected catastrophic floods that drained from Noctis, through Valles Marineris, and out into the northern lowland plains to the east, eons ago when this dry equatorial region could have been wet.
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Today’s cool image once again illustrates that the things that orbiters photograph on the Martian surface are not always what they seem at first glance. The picture to the right, cropped, reduced, and sharpened to post here, was taken on March 23, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows what the scientists label as “layering” in this small mile-wide crater.

That layering, seen on both the interior and exterior slopes of its circular rim, is what makes this crater puzzling. It suggests this crater was not formed by an impact, but by volcanism. The layers suggest repeated eruptive events. That the crater sits above the surround plain by about 100 feet strengthens this conclusion.

And yet, a look at the overview map below suggests this conclusion is premature.
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Cool image time! The picture to the right, rotated, cropped, reduced, sharpened, and annotated to post here, was taken on April 8, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

The picture shows a terrain of swirls and terraced mesas. Because the shadows are deceptive, I have annotated the picture to show the actual drainage pattern of those swirls, suggesting that whatever material forms these swirls is not only draining about 200-250 feet down into the low point at the picture’s center, the swirls are also draining toward the small 1,000-foot-wide crater in the upper left. That crater however appears to lie on top of the swirls, which means it came after them.

What are the swirls made of?
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Cool image time! The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on April 16, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows in the center an ancient tongue of lava flow that is surrounded by thick dust fields on the north and the south.

The arrow indicates the downhill grade. It also shows the direction of the prevailing winds, downhill to sculpt the volcanic ash into long streamers of parallel grooves, with obvious eddies forming around bits of older lava that still stick up through the ash. On the lava flow can also be seen one small volcano cone, on the picture’s right edge, suggesting that either during this flow or after it hardened magma bubbled up from below.

The location is fascinating, and in fact puts this picture into its much more spectacular context.
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Cool image time! The picture above, rotated, reduced, and brightened slightly to post here, was taken on April 13, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It cuts a swath across an eleven-mile-wide crater only about 500 miles from the edge of Mars’ north pole ice cap.

The overview map to the right marks its location, as indicated by the white dot on the right edge of the map. The inset shows the soft and likely icy nature of the surface in which this impact occurred. The crater resulted in a secondary outside ripple, that quickly hardened after impact.

The image was taken during spring, shortly after the sun’s light hit this crater. The cracks in the ice indicate long term sublimation that is slowly reducing the amount of water ice inside the crater. Like mud cracks in the desert after a puddle has evaporated, the ice here is cracking to produce polygon fractures.

It is also very likely that everything here is coated with a thin mantle of clear dry ice, deposited as snow from the atmosphere in the winter and then sublimating away with the coming of spring. That spring dry ice sublimation is likely ongoing, and this picture is probably an attempt by scientists to detect that process.

Why the surface colors shift from aquablue to orange might have to do with that sublimation process, or it might be revealing areas covered with dust (orange). That the northern parts of the strip is blue and the southern parts orange suggests the former. Or not. I don’t have enough information to answer this question with any confidence.

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Cool image time. The picture to the right, cropped to post here, was taken on March 14, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). Dubbed simply a “terrain sample,” this image was likely taken not as part of any specific research project, but to fill a gap in the camera’s schedule in order to maintain its temperature by taking regular images. When the camera team needs to do this, they try to find interesting locations not previously photographed. Sometimes the photos turn out somewhat boring. Most of the time however they capture something very intriguing.

In this case, the intriguing feature of this picture is its stippled surface that seems to overlay a relatively flat surface underneath, with some faint covered craters visible. On top are several more recent craters that suggest either the impact landed in very soft material, thus producing little ejecta and no crater rims or the craters are not craters but sinks, places where the ground is subsiding due to some underground process.
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