Isolated flat-topped mesa inside large Martian crater
Click for original image.
Cool image time! The picture to the right, cropped and reduced to post here, was taken on February 18, 2024 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).
The camera team labels this “layers in butte”, but because we are looking straight down at this 400-foot-high butte, it is difficult to see any layers at all. Based on most Martian geology however it would be shocking if this butte is not made up of multiple horizontal layers, ending with that flat surface layer at the top. Moreover, the base of the mesa to the northeast is clearly made up of a series of terraces that appear obscured at other points due to the presence of dust and dunes.
A side view would help clarify the number of layers and their thickness, but it does appear that this butte contains evidence of the geology that once covered this whole area, but over eons has eroded everything away but this butte.
On the overview map to the right the small rectangle inside 250-mile-wide Cassini Crater marks the location. The inset shows that this mesa sits inside a depression that appears to widen to the west. Thus, the mesa’s top appears to give us a glimpse of the same surface seen on the plateaus to the north and south. Erosion has removed the material in-between to leave the mesa sitting alone inside this depression.
Elevation data however shows that the mesa top is actually higher than the plateaus to the north and south, suggesting this mesa was the high point of that plateau, before erosion left it isolated.
Why did the mesa not get worn away as well? My guess is that the top of the mesa is actually the floor of an ancient crater. The impact compressed the ground so that it was more resistent to erosion. When the surrounding terrain was worn away, the crater remained, and eventually became the isolated mesa we see now.
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 original image.
Cool image time! The picture to the right, cropped and reduced to post here, was taken on February 18, 2024 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).
The camera team labels this “layers in butte”, but because we are looking straight down at this 400-foot-high butte, it is difficult to see any layers at all. Based on most Martian geology however it would be shocking if this butte is not made up of multiple horizontal layers, ending with that flat surface layer at the top. Moreover, the base of the mesa to the northeast is clearly made up of a series of terraces that appear obscured at other points due to the presence of dust and dunes.
A side view would help clarify the number of layers and their thickness, but it does appear that this butte contains evidence of the geology that once covered this whole area, but over eons has eroded everything away but this butte.
On the overview map to the right the small rectangle inside 250-mile-wide Cassini Crater marks the location. The inset shows that this mesa sits inside a depression that appears to widen to the west. Thus, the mesa’s top appears to give us a glimpse of the same surface seen on the plateaus to the north and south. Erosion has removed the material in-between to leave the mesa sitting alone inside this depression.
Elevation data however shows that the mesa top is actually higher than the plateaus to the north and south, suggesting this mesa was the high point of that plateau, before erosion left it isolated.
Why did the mesa not get worn away as well? My guess is that the top of the mesa is actually the floor of an ancient crater. The impact compressed the ground so that it was more resistent to erosion. When the surrounding terrain was worn away, the crater remained, and eventually became the isolated mesa we see now.
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
Readers: the rules for commenting!
No registration is required. I welcome all opinions, even those that strongly criticize my commentary.
However, name-calling and obscenities will not be tolerated. First time offenders who are new to the site will be warned. Second time offenders or first time offenders who have been here awhile will be suspended for a week. After that, I will ban you. Period.
Note also that first time commenters as well as any comment with more than one link will be placed in moderation for my approval. Be patient, I will get to it.