Erosion at the edge of Mars’ biggest volcanic ash field
Click for full image.
Cool image time! The photo to the right, rotated, cropped, reduced, and sharpened to post here, was taken on August 13, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It is another fine example of the wind-blown sculpted terrain that one finds routinely in Mars’ largest volcanic ash field, dubbed the Medusae Fossae Formation. About the size of India, this gigantic field is thought to be the source of most of the dust on Mars.
This particular location sits on the northernmost edge of that huge field. The elongated mesas mark the field’s edge, disappearing to the north but becoming thick and extensive to the south. The prevailing southeast-to-northwest winds have acted to clean most of the ash away.
We can get an idea about how deep and pervasive that field once was at this location by the pedestal crater in the middle right. Once, the floor of that crater was below the top of the ash field. At that time, the top of the dunes marked the general ground level across this entire image. Over time, the winds blew most of this material away, but the denser packed floor of the crater resisted that erosion, and thus now stands above the surrounding terrain.
The more normal-looking craters nearby could have occurred before the ash was deposited, or after it was blown away. The impact that created the pedestal crater however occurred when the ash covered everything here.
The white cross on the overview map to the right marks the location of this image. If you look close at the full resolution image, you will see that these mesas are made up of multiple layers, with each layer likely the result of a nearby major volcanic eruption from one of the many mammoth volcanoes to the east and west. The flat terrain on which they sit is likely a hard lava flood plain, not ash. This flood lava was likely laid down first, then covered with the volcanic ash, which has now blown away.
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In 2020 when the world panicked over COVID I wrote that the panic was unnecessary, that the virus was apparently simply a variation of the flu, that masks were not simply pointless but if worn incorrectly were a health threat, that the lockdowns were a disaster and did nothing to stop the spread of COVID. Only in the past year have some of our so-called experts in the health field have begun to recognize these facts.
Your help allows me to do this kind of intelligent analysis. I take no advertising or sponsors, so my reporting isn't influenced by donations by established space or drug companies. Instead, I rely entirely on donations and subscriptions from my readers, which gives me the freedom to write what I think, unencumbered by outside influences.
You can support me either by giving a one-time contribution or a regular subscription. There are four ways of doing so:
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Click for full image.
Cool image time! The photo to the right, rotated, cropped, reduced, and sharpened to post here, was taken on August 13, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It is another fine example of the wind-blown sculpted terrain that one finds routinely in Mars’ largest volcanic ash field, dubbed the Medusae Fossae Formation. About the size of India, this gigantic field is thought to be the source of most of the dust on Mars.
This particular location sits on the northernmost edge of that huge field. The elongated mesas mark the field’s edge, disappearing to the north but becoming thick and extensive to the south. The prevailing southeast-to-northwest winds have acted to clean most of the ash away.
We can get an idea about how deep and pervasive that field once was at this location by the pedestal crater in the middle right. Once, the floor of that crater was below the top of the ash field. At that time, the top of the dunes marked the general ground level across this entire image. Over time, the winds blew most of this material away, but the denser packed floor of the crater resisted that erosion, and thus now stands above the surrounding terrain.
The more normal-looking craters nearby could have occurred before the ash was deposited, or after it was blown away. The impact that created the pedestal crater however occurred when the ash covered everything here.
The white cross on the overview map to the right marks the location of this image. If you look close at the full resolution image, you will see that these mesas are made up of multiple layers, with each layer likely the result of a nearby major volcanic eruption from one of the many mammoth volcanoes to the east and west. The flat terrain on which they sit is likely a hard lava flood plain, not ash. This flood lava was likely laid down first, then covered with the volcanic ash, which has now blown away.
Readers!
Please consider supporting my work here at Behind the Black. Your support allows me the freedom and ability to analyze objectively the ongoing renaissance in space, as well as the cultural changes -- for good or ill -- that are happening across America. Fourteen years ago I wrote that SLS and Orion were a bad ideas, a waste of money, would be years behind schedule, and better replaced by commercial private enterprise. Only now does it appear that Washington might finally recognize this reality.
In 2020 when the world panicked over COVID I wrote that the panic was unnecessary, that the virus was apparently simply a variation of the flu, that masks were not simply pointless but if worn incorrectly were a health threat, that the lockdowns were a disaster and did nothing to stop the spread of COVID. Only in the past year have some of our so-called experts in the health field have begun to recognize these facts.
Your help allows me to do this kind of intelligent analysis. I take no advertising or sponsors, so my reporting isn't influenced by donations by established space or drug companies. Instead, I rely entirely on donations and subscriptions from my readers, which gives me the freedom to write what I think, unencumbered by outside influences.
You can support me either by giving a one-time contribution or a regular subscription. There are four ways of doing so:
1. Zelle: This is the only internet method that charges no fees. All you have to do is use the Zelle link at your internet bank and give my name and email address (zimmerman at nasw dot org). What you donate is what I get.
2. Patreon: Go to my website there and pick one of five monthly subscription amounts, or by making a one-time donation.
3. A Paypal Donation or subscription:
4. Donate by check, payable to Robert Zimmerman and mailed to
Behind The Black
c/o Robert Zimmerman
P.O.Box 1262
Cortaro, AZ 85652
You can also support me by buying one of my books, as noted in the boxes interspersed throughout the webpage or shown in the menu above.
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