Rimstone dams in Mars’ youngest lava deposit
Click for original image.
Cool image time! The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on April 23, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).
The scientists dub the features here merely as “land forms,” probably because it is difficult to explain the origins of many of these strange features. For example, why is the half-mile-wide crater filled that knobby terrain, far different than the surrounding plains? Similarly, what caused the small meandering ridges (less than five feet high) that appear to closely resemble the cave formation called rimstone dams?
And why is this terrain so generally flat and smooth?
As usual, the overview map helps explains some of this, but not all.
On the overview map to the right, the white dot south of the giant shield volcano Elysium Mons and within the Athabasca Valles flood lava plain marks this location. We are looking at that young flood lava, with the white arrow indicating the direction of flow. The eddies south of the small hills on the right side of the image also points to a southward flow direction.
Athabasca erupted northeast of this spot about 20 million years ago, flowing to the southwest before dividing into two flows, one to the southeast and the second to the west. From the western flow another flow then branched off to the south, which this picture shows.
The rim of the knobby crater is only fifty feet high, but apparently that was enough to divert the flood lava around, so that the interior of this crater shows terrain that is older than Athabasca.
What caused the knobby interior of the crater remains to me a mystery. The rimstone dams might indicate the front of several overlaying lava flows, all heading south. The dams farthest south probably represent the longest and oldest flows, with later flows overlaying each but not going as far south, the dams marking where the flow stopped short..
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 print edition can be purchased at Amazon. from any other book seller, or direct from my ebook publisher, ebookit.
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, rotated, cropped, reduced, and sharpened to post here, was taken on April 23, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).
The scientists dub the features here merely as “land forms,” probably because it is difficult to explain the origins of many of these strange features. For example, why is the half-mile-wide crater filled that knobby terrain, far different than the surrounding plains? Similarly, what caused the small meandering ridges (less than five feet high) that appear to closely resemble the cave formation called rimstone dams?
And why is this terrain so generally flat and smooth?
As usual, the overview map helps explains some of this, but not all.
On the overview map to the right, the white dot south of the giant shield volcano Elysium Mons and within the Athabasca Valles flood lava plain marks this location. We are looking at that young flood lava, with the white arrow indicating the direction of flow. The eddies south of the small hills on the right side of the image also points to a southward flow direction.
Athabasca erupted northeast of this spot about 20 million years ago, flowing to the southwest before dividing into two flows, one to the southeast and the second to the west. From the western flow another flow then branched off to the south, which this picture shows.
The rim of the knobby crater is only fifty feet high, but apparently that was enough to divert the flood lava around, so that the interior of this crater shows terrain that is older than Athabasca.
What caused the knobby interior of the crater remains to me a mystery. The rimstone dams might indicate the front of several overlaying lava flows, all heading south. The dams farthest south probably represent the longest and oldest flows, with later flows overlaying each but not going as far south, the dams marking where the flow stopped short..
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 print edition can be purchased at Amazon. from any other book seller, or direct from my ebook publisher, ebookit. 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.