Tag: geology

Click for full image.

Cool image time! The photo to the right, cropped and reduced to post here, was taken on June 21, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). The location is a very eroded crater at about 26 degrees north latitude. The image shows the crater’s crater floor, with a variety of bedrock-type features, sharp ridges, abrupt scarps, and flat smooth plateaus, with a hint of lobate glacial flows in the image’s southeast quadrant.

At 26 north latitude, it is unlikely that anything here is icy, unless it is very well protected by debris. Most of these features are almost certainly bedrock, though their formation could very well have been shaped by ice in past eons when this location was more amenable to water ice.

The wider MRO context camera image of the entire crater, plus the overview map, give a larger picture, and raise some interesting questions.
» Read more

Cool image time! The photo to the right, cropped, reduced, and rotated so that north is up, was taken on May 12, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows the strange lacy patterns seen routinely in the very high northern latitudes surrounding the Martian north pole.

Located in a region of the vast northern lowland plains dubbed Scandia Tholi, such features are apparently common here. From a 2011 geology paper of the region’s geological history:

We find that Scandia Tholi display concentric ridges, rugged peaks, irregular depressions, and moats that suggest uplift and tilting of layered plains material by diapirs and extrusion, erosion, and deflation of viscous, sedimentary slurries as previously suggested. These appear to be long-lived features that both pre-date and post-date impact craters.

The small circular feature near the bottom of the picture appears to be a mesa, and might be a pedestal crater, so old that the surrounding terrain has worn away and left the hardened-by-impact crater as a butte. To its right is a larger circular mesa with its scarp well eroded into hollows. This might also be a pedestal crater, or not.

The white lacy patterns could be frost, either water ice or dry ice. That the white lace tends to favor the north-facing slopes lends support to this guess. The photo was taken in the early spring, so the thin mantle of carbon dioxide that falls to cover the polar region south to sixty degrees latitude is only beginning to sublimate away.

Click for full image.

Cool image time! The photo to the right, rotated, cropped, and reduced to post here, was taken on June 17, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows a somewhat straight depression with several wider and deeper pits along it.

The feature immediately suggests sinkholes that exist because the ground is sagging into voids below ground. Yet, both the straight and circular depressions also appear filled, showing no evidence that they connect to any below ground cavities.

Are the sinks the result of a fissure produced by a graben, when two large blocks shift relative to each other to cause a fissure to appear? Or are they evidence of an underground lava tube? Or maybe they are the filled remains of a now mostly buried canyon carved by water or ice?

As always, a wider view helps clarify things, though whether it answers the question is uncertain.
» Read more

Click for full image.

Cool image time! The photo to the right, rotated, cropped, and reduced to post here, was taken on June 29, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). The location is in Mars’ glacier country, that strip of chaos terrain that runs about 2,000 miles along the transition zone between the northern lowland plains and the southern cratered highlands at 30 to 47 degrees north latitude. This particular feature is located in Deuteronilus Mensae, the westernmost region of that strip of chaos.

I call this glacier country because practically every image taken by MRO’s high resolution camera in this region suggests the presence of glacial material covered by a protective layer of debris. The photo to the right is typical, though a bit more puzzling because of the depressions that appear to run along highpoints.

As usual, the overview map below helps explain what we are looking at.
» Read more

Click for full image.

Cool image time! The photo to the right, cropped to post here, was taken on May 14, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows what the science team labels as “light-toned layered deposits.”

Their focus, rightly from a geologist’s perspective, is the contrast in color between different layers, suggesting different composition and thus a different formation history for each layer.

To me, what made this feature appealing is the thinness and number of its layers. It reminded me of fillo pastry, “unleavened flour dough formed into very thin sheets or leaves.”

If you look at the full image you will see that cropped section only covers one edge of a tongue-shaped plateau, with similar layers revealed along its entire cliff wall. It is almost like those layers have been peeling off for eons to leave the plateau behind.

The location below gives some context.
» Read more

Click for full image.

Time for another “What the heck?” image. The photo to the right, cropped to post here, was taken on May 18, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows what appears to be a series of white circular features aligned with a ridge line.

Are these eroded craters? Maybe, but their alignment with those ridges suggests otherwise. If you look at the full image, you will see further parallel ridges to the north and south, also with similar circular blobs lined along them. Furthermore, the flat surrounding terrain, part of the northern lowland plains north of the resurgences from Valles Marineris, has a scattering of very normal looking craters, with distinct rims and even some glacial material within. As this is at 44 degrees north latitude, the presence of glacial material inside craters is not surprising.

Thus, the white blobs are likely not craters, but some form of eruptive material from below, coming up along those ridges which are probably faultlines. The whiteness suggests that material is water ice, but this of course is unconfirmed.

The question is of course, why? What would cause water ice to erupt along these faultlines? And why are such features not seen elsewhere? Faults and underground ice are common on Mars. Yet, I don’t remember seeing features such as this in any other Martian images.

Click for full image.

A quick cool image! The photo to the right, rotated, cropped and reduced to post here, was taken by the high resolution camera on Mars Reconnaissance Orbiter (MRO) more than a decade ago, on June 1, 2010. I post it now because it is today’s MRO picture of the day, and is definitely cool. The caption:

One of a few “scaly-looking” inselbergs within regional platy-ridged flows in Elysium Planitia. This inselberg has a broken and blocky appearance with some of the blocks being tilted. Could this be the remnant of a once extensive mantling deposit? An inselberg is an isolated hill or mountain rising abruptly from a plain.

The wider image by MRO’s context camera below, also rotated, cropped and reduced to post here, illustrates even more forcefully how isolated this circular set of blocks is.
» Read more

Click for full image.

Cool image time! The photograph to the right, cropped and reduced to post here, was taken by the high resolution camera on Mars Reconnaissance Orbiter on May 27, 2021. A sample image, likely taken not as part of any specific scientist’s research but by the camera team in order to maintain the camera’s temperature, shows an area of the Martian northern plains that appears filled with rough scattered depressions, possibly caused by sublimation of buried ice.

The location, at 54 degrees north latitude, is far enough north to easily have a lot of buried ice. It is also only about 40 miles to the east of Milankovič Crater, where scientists have found many scarps that appear to have exposed layers of ice in their cliff faces.

However, the location has other components that must raise questions about this sublimating ice hypothesis.
» Read more

Click for full image.

Cool image time! The photo to the right, rotated, cropped, and reduced to post here, was taken by the high resolution camera on Mars Reconnaissance Orbiter (MRO) on April 25, 2021. It grabbed my attention because it possibly captures a whole range of Martian geological processes, all in one place, including evidence of quakes, of lava, of faults, and possibly of glaciers.

First, ignore the black rectangle, which is merely a small section of lost data.

The picture itself shows a wide north-south fissure, as indicated by the distinct western cliff and the fainter and less pronounced eastern cliff. This fissure, likely formed along a fault, was created when the crust was pushed and stretched upward by the pressure of underground volcanic magma, part of the long series of eruptions that formed the many similar and parallel north-south fissures south of the shield volcano Alba Mons.

The overview map below illustrates this fissure’s relationship with Alba Mons.
» Read more