Remnant moraine on Mars
Click for full image.
Cool image time! Using both Martian orbiters and rovers scientists are increasingly convinced that Mars has lots of buried glaciers in its mid-latitudes. These glaciers are presently either inactive or shrinking, their water ice sublimating away as gas, either escaping into space or transporting to the colder poles.
The image to the right, cropped and reduced to post here, shows some apparent proof of this process. Taken by the high resolution camera of Mars Reconnaissance Orbiter (MRO) on December 23, 2019, it shows a weird meandering ridge crossing the floor of a crater. The north and south parts of the crater rim are just beyond the cropped image, so that the gullied slope in the image’s lower left is actually a slope coming down from that rim.
My first reaction upon seeing this image was how much that ridge reminded me of the strange rimstone dams you often find on cave floors, formed when calcite in the water condenses out at the edge of the pond and begins to build up a dam over time.
This Martian ridge was certainly not formed by this process. To get a more accurate explanation, I contacted Dan Berman, senior scientist at the Planetary Science Institute in Arizona, who had requested this image. He explained:
The ridge in the image is of glacial origin. The glacier once flowed from the hill to the lower left of the image (flow to the upper right), and most of the ice has since sublimated away, and the surface is now covered by gullies and their apron deposits. Parts of the ridge may represent the furthest margin of the glacier and may still contain ice. The layering seen in the ridge could indicate that it formed over a series of depositional cycles, when ice and dust fell atmospherically, likely during periods of high Martian obliquity. Parts of the ridge may be moraine like features, where the glacier pushed material as it flowed.
His reference to “high Martian obliquity” has to do with the large changes to Mars’ inclination that occur repeatedly over time. Right now the planet has a tilt similar to the Earth, 25 degrees. In the past that tilt was as much as 60 degrees, during which the mid-latitudes where this crater is located (43 degrees south) were actually colder than the poles. Then, water was cycling from the poles to the mid-latitudes where it fell as snow, causing these glaciers to flow and push their moraines before them.
At today’s 25 degrees inclination, the glaciers at the mid-latitudes are either inactive, or sublimating away. This is what happened here, exposing the underlying gullies that had been carved out by the moving glacier and its melting water. The moraine, made of rocks and dirt pushed down by the glacier, formed the ridge at the foot of the glacier, and remains there after the glacier has largely disappeared.
The location of this crater is also interesting, as it sits at the northern margin of Argyre Basin, the second largest basin on Mars that was probably caused by a major impact event. The overview map to the right gives a sense of its location on Mars, in the southern cratered highlands south of Valles Marineris.
Though Argyre Basin is more than a thousand miles across with a depth greater than three miles, for no understandable reason none of my previous cool images have been located in it. This image ends that drought.
Just for fun, I might do a survey of old MRO high resolution images in Argyre. I am sure there are other very cool images there that I have missed.
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.
Click for full image.
Cool image time! Using both Martian orbiters and rovers scientists are increasingly convinced that Mars has lots of buried glaciers in its mid-latitudes. These glaciers are presently either inactive or shrinking, their water ice sublimating away as gas, either escaping into space or transporting to the colder poles.
The image to the right, cropped and reduced to post here, shows some apparent proof of this process. Taken by the high resolution camera of Mars Reconnaissance Orbiter (MRO) on December 23, 2019, it shows a weird meandering ridge crossing the floor of a crater. The north and south parts of the crater rim are just beyond the cropped image, so that the gullied slope in the image’s lower left is actually a slope coming down from that rim.
My first reaction upon seeing this image was how much that ridge reminded me of the strange rimstone dams you often find on cave floors, formed when calcite in the water condenses out at the edge of the pond and begins to build up a dam over time.
This Martian ridge was certainly not formed by this process. To get a more accurate explanation, I contacted Dan Berman, senior scientist at the Planetary Science Institute in Arizona, who had requested this image. He explained:
The ridge in the image is of glacial origin. The glacier once flowed from the hill to the lower left of the image (flow to the upper right), and most of the ice has since sublimated away, and the surface is now covered by gullies and their apron deposits. Parts of the ridge may represent the furthest margin of the glacier and may still contain ice. The layering seen in the ridge could indicate that it formed over a series of depositional cycles, when ice and dust fell atmospherically, likely during periods of high Martian obliquity. Parts of the ridge may be moraine like features, where the glacier pushed material as it flowed.
His reference to “high Martian obliquity” has to do with the large changes to Mars’ inclination that occur repeatedly over time. Right now the planet has a tilt similar to the Earth, 25 degrees. In the past that tilt was as much as 60 degrees, during which the mid-latitudes where this crater is located (43 degrees south) were actually colder than the poles. Then, water was cycling from the poles to the mid-latitudes where it fell as snow, causing these glaciers to flow and push their moraines before them.
At today’s 25 degrees inclination, the glaciers at the mid-latitudes are either inactive, or sublimating away. This is what happened here, exposing the underlying gullies that had been carved out by the moving glacier and its melting water. The moraine, made of rocks and dirt pushed down by the glacier, formed the ridge at the foot of the glacier, and remains there after the glacier has largely disappeared.
The location of this crater is also interesting, as it sits at the northern margin of Argyre Basin, the second largest basin on Mars that was probably caused by a major impact event. The overview map to the right gives a sense of its location on Mars, in the southern cratered highlands south of Valles Marineris.
Though Argyre Basin is more than a thousand miles across with a depth greater than three miles, for no understandable reason none of my previous cool images have been located in it. This image ends that drought.
Just for fun, I might do a survey of old MRO high resolution images in Argyre. I am sure there are other very cool images there that I have missed.
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.
“formed when calcite in the water condenses out at the edge of the pond”
Good analogy! However, from a chemist’s view, that would be crystallizes not condenses.
A profile of the land would certainly help ones perspective.