Black dunes and weird hills on Mars
Click for full image.
Cool image time! Or I should say a bunch of cool images! The photo on the right, rotated, cropped, reduced, and annotated by me, was taken by the high resolution camera on Mars Reconnaissance Orbiter (MRO) on February 3, 2020. An uncaptioned image, it was entitled “Arabia Terra with Stair-Stepped Hills and Dark Dunes.” Arabia Terra is one of the largest regions of the transition zone on Mars between the northern lowland plains and the southern cratered highlands. It is also where Opportunity landed, and where Europe’s Rosalind Franklin rover will land, in 2022.
This image has so many weird and strange features, I decided to show them all, Below are the three areas indicated by the white boxes, at full resolution. One shows the black dunes, almost certainly made up of sand ground from volcanic ash spewed from a long ago volcanic eruption on Mars.
The first image shows a close up of the black dunes. What I find interesting is that these large dunes appear to sit on top of a series of parallel ridges of lighter material. Those ridges could be very old sand dunes themselves, now hardened into a type of sandstone.
Over time the darker sand dunes crept over them, blown as separate clumps traveling as units, the sand on top blown off to fall to the base to be covered by later windblown sand, almost like an eddy in a river.
The two dune features also appear to show a change in prevailing winds. With the newer black dunes the wind blows from the northwest to the southwest. If the lighter older parallel ridges were once dunes, the wind apparently blew in a direction 90 degrees different.
Then again, those lighter ridges might not have been wind-driven dunes. Instead, they have been caused by lapping water at the edge of a shallow sea to the north. In the full image we can see ridges oriented in this manner in several other places, and all appear to be aligned facing the lower flat region at the top of the photograph.
The second and third images to the right show several of the stair-stepped hills seen near the bottom of the photograph. These once again suggest to me the lapping of water at different depths at different times, like we are looking at the dried-out shoreline of an ancient ocean. Once, that ocean surrounded these mesas, and as the sea level changed it caused the terraced erosion.
Later, and for a long time since, wind has further shaped these mesas, which might have once been chaos terrain, but with time were eaten away until only some knobs and terraced hills remain.
Or not. My guess is as good as yours.
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! Or I should say a bunch of cool images! The photo on the right, rotated, cropped, reduced, and annotated by me, was taken by the high resolution camera on Mars Reconnaissance Orbiter (MRO) on February 3, 2020. An uncaptioned image, it was entitled “Arabia Terra with Stair-Stepped Hills and Dark Dunes.” Arabia Terra is one of the largest regions of the transition zone on Mars between the northern lowland plains and the southern cratered highlands. It is also where Opportunity landed, and where Europe’s Rosalind Franklin rover will land, in 2022.
This image has so many weird and strange features, I decided to show them all, Below are the three areas indicated by the white boxes, at full resolution. One shows the black dunes, almost certainly made up of sand ground from volcanic ash spewed from a long ago volcanic eruption on Mars.
The first image shows a close up of the black dunes. What I find interesting is that these large dunes appear to sit on top of a series of parallel ridges of lighter material. Those ridges could be very old sand dunes themselves, now hardened into a type of sandstone.
Over time the darker sand dunes crept over them, blown as separate clumps traveling as units, the sand on top blown off to fall to the base to be covered by later windblown sand, almost like an eddy in a river.
The two dune features also appear to show a change in prevailing winds. With the newer black dunes the wind blows from the northwest to the southwest. If the lighter older parallel ridges were once dunes, the wind apparently blew in a direction 90 degrees different.
Then again, those lighter ridges might not have been wind-driven dunes. Instead, they have been caused by lapping water at the edge of a shallow sea to the north. In the full image we can see ridges oriented in this manner in several other places, and all appear to be aligned facing the lower flat region at the top of the photograph.
The second and third images to the right show several of the stair-stepped hills seen near the bottom of the photograph. These once again suggest to me the lapping of water at different depths at different times, like we are looking at the dried-out shoreline of an ancient ocean. Once, that ocean surrounded these mesas, and as the sea level changed it caused the terraced erosion.
Later, and for a long time since, wind has further shaped these mesas, which might have once been chaos terrain, but with time were eaten away until only some knobs and terraced hills remain.
Or not. My guess is as good as yours.
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.
Photo 1: Martian Solar energy complex. Black tent-like structures to absorb light and generate power.
Photo 2: Martian domes covering a city complex.
Photo 3: (Especially the odd, chaotic shaped mega-dome) Martian Government Complex.
Cheers…