Tag: geology

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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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