Glacier layers on the border of Hellas Basin
Click for original image.
Cool image time! The picture to the right, cropped and reduced to post here, was taken on February 21, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows what the scientists label as “dipping layers”, referring specifically to the mesas with the terraces on their western flanks.
The layers obviously signify past cycles of geological events on Mars. That the terraces are only on one side of the mesas suggests that they are tilted, with the downhill grade to the east.
These layers however pose several mysteries. First, why are they located so specifically in only certain places of this region? It appears that the layered terrain is only found in the lower hollows and valleys. Why?
Second, why are they tilted at all?
The red dot on the overview map to the right marks this location, on the eastern border of Hellas Basin, the death valley of Mars. The location is also on the edge of Reull Valles, a canyon that from MRO images appears to be completely filled with glacial material. In fact, this entire region east of Hellas is chock full of glacial material, located in the southern mid-latitudes. It is also a region where other images have identified similar dipping layers.
In this particular image, the dipping layers are probably the remnant remains of the glaciers that once filled the hollows and valleys at this location.
Why these particular ice layers are tilted however remains a mystery. Glacial ice is almost always oriented level by gravity. To have ice tilt like this means it has been frozen for a very long time, long enough for these multiple layers to be structurally strong enough for other processes to pick up them up as a group and tilt them sideways. What process picked them up to tilted them however is not evident.
Once exposed however the thin atmosphere of Mars should cause this ice to sublimate away, a process which likely explains the terracing we see. The top layers have sublimated more than the lower layers, forming the terraces.
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, cropped and reduced to post here, was taken on February 21, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows what the scientists label as “dipping layers”, referring specifically to the mesas with the terraces on their western flanks.
The layers obviously signify past cycles of geological events on Mars. That the terraces are only on one side of the mesas suggests that they are tilted, with the downhill grade to the east.
These layers however pose several mysteries. First, why are they located so specifically in only certain places of this region? It appears that the layered terrain is only found in the lower hollows and valleys. Why?
Second, why are they tilted at all?
The red dot on the overview map to the right marks this location, on the eastern border of Hellas Basin, the death valley of Mars. The location is also on the edge of Reull Valles, a canyon that from MRO images appears to be completely filled with glacial material. In fact, this entire region east of Hellas is chock full of glacial material, located in the southern mid-latitudes. It is also a region where other images have identified similar dipping layers.
In this particular image, the dipping layers are probably the remnant remains of the glaciers that once filled the hollows and valleys at this location.
Why these particular ice layers are tilted however remains a mystery. Glacial ice is almost always oriented level by gravity. To have ice tilt like this means it has been frozen for a very long time, long enough for these multiple layers to be structurally strong enough for other processes to pick up them up as a group and tilt them sideways. What process picked them up to tilted them however is not evident.
Once exposed however the thin atmosphere of Mars should cause this ice to sublimate away, a process which likely explains the terracing we see. The top layers have sublimated more than the lower layers, forming the terraces.
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
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