Inverted Martian tadpole
Click for full image.
Cool image time! On Mars it is not unusual to see what scientists call tadpole features, craters with meandering canyons or channels either flowing into or out from the crater’s rim. The photo to the right, rotated, cropped, and reduced to post here, is another example, though with one major difference. The channel and crater are inverted, with the channel instead a ridge and the crater a circular plateau. The picture itself was taken on April 16, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).
Orbital images have found on Mars a lot of what scientists call pedestal craters, where the impact packed and hardened the ground under the crater so that when the surrounding terrain eroded away the crater remained, as a plateau.
Scientists have also found on Mars a lot of what they call “inverted channels,” places where the channels of a drainage pattern followed the same geological process, becoming more resistant to erosion so that over time it turned from a channel to a ridge.
Here we have a combination of both. The overview map below provides us the larger picture.
The white dot about 250 miles north of where the rover Opportunity landed marks this photo’s location in Arabia Terra, the largest region in the transition zone between the northern lowland plains and the southern cratered highlands.
What is most striking about this photo is the sense that we are looking at hard bedrock that has been scoured away with time, leaving a flat surface with the most resistant pavement remaining. This erosion also reveals the circular impact fractures produced around that crater when the bolide smashed into the ground. Normally these fractures would have been buried under the ejecta that formed the crater rim. With that ejecta now gone, we can see evidence of the fractures instead.
On Christmas Eve 1968 three Americans became the first humans to visit another world. What they did to celebrate was unexpected and profound, and will be remembered throughout all human history. Genesis: the Story of Apollo 8, Robert Zimmerman's classic history of humanity's first journey to another world, tells that story, and it is now available as both an ebook and an audiobook, both with a foreword by Valerie Anders and a new introduction by Robert Zimmerman.
The ebook is available everywhere for $5.99 (before discount) at amazon, or direct from my ebook publisher, ebookit. If you buy it from ebookit you don't support the big tech companies and the author gets a bigger cut much sooner.
The audiobook is also available at all these vendors, and is also free with a 30-day trial membership to Audible.
"Not simply about one mission, [Genesis] is also the history of America's quest for the moon... Zimmerman has done a masterful job of tying disparate events together into a solid account of one of America's greatest human triumphs."--San Antonio Express-News
Click for full image.
Cool image time! On Mars it is not unusual to see what scientists call tadpole features, craters with meandering canyons or channels either flowing into or out from the crater’s rim. The photo to the right, rotated, cropped, and reduced to post here, is another example, though with one major difference. The channel and crater are inverted, with the channel instead a ridge and the crater a circular plateau. The picture itself was taken on April 16, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).
Orbital images have found on Mars a lot of what scientists call pedestal craters, where the impact packed and hardened the ground under the crater so that when the surrounding terrain eroded away the crater remained, as a plateau.
Scientists have also found on Mars a lot of what they call “inverted channels,” places where the channels of a drainage pattern followed the same geological process, becoming more resistant to erosion so that over time it turned from a channel to a ridge.
Here we have a combination of both. The overview map below provides us the larger picture.
The white dot about 250 miles north of where the rover Opportunity landed marks this photo’s location in Arabia Terra, the largest region in the transition zone between the northern lowland plains and the southern cratered highlands.
What is most striking about this photo is the sense that we are looking at hard bedrock that has been scoured away with time, leaving a flat surface with the most resistant pavement remaining. This erosion also reveals the circular impact fractures produced around that crater when the bolide smashed into the ground. Normally these fractures would have been buried under the ejecta that formed the crater rim. With that ejecta now gone, we can see evidence of the fractures instead.
On Christmas Eve 1968 three Americans became the first humans to visit another world. What they did to celebrate was unexpected and profound, and will be remembered throughout all human history. Genesis: the Story of Apollo 8, Robert Zimmerman's classic history of humanity's first journey to another world, tells that story, and it is now available as both an ebook and an audiobook, both with a foreword by Valerie Anders and a new introduction by Robert Zimmerman.
The ebook is available everywhere for $5.99 (before discount) at amazon, or direct from my ebook publisher, ebookit. If you buy it from ebookit you don't support the big tech companies and the author gets a bigger cut much sooner.
The audiobook is also available at all these vendors, and is also free with a 30-day trial membership to Audible.
"Not simply about one mission, [Genesis] is also the history of America's quest for the moon... Zimmerman has done a masterful job of tying disparate events together into a solid account of one of America's greatest human triumphs."--San Antonio Express-News
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