An ancient Martian river system now meandering ridges
Cool image time! The picture to the right, cropped and reduced to post here, was taken on August 27, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It was featured by MRO’s science team yesterday, in which Shane Byrne of the Lunar and Planetary Lab University of Arizona wrote the following:
River beds often get filled with gravel and the surrounding terrain is often built up of fine-grained mud from river overflows. The gravely river bottom and the fine-grained surroundings can lead to a strange phenomenon that geologists call inverted channels. After the river disappears, the fine-grained surroundings can be easily eroded away leaving the gravely river bed as a high-standing ridge.
These ridges show the location of the old river beds in Mars’ distant past. The angle at which the ridges join together indicate that these rivers flowed from top-right to bottom-left (i.e. southwest).
The picture above is a mosaic produced from the global survey taken by MRO’s lower resolution context camera. It gives us a fuller picture of this river system, with the rectangle showing the small area covered by the photo on the right. Overall this ancient and extinct river of ridges travels more than thirty miles downhill from the northeast to the southwest.
The white dot on the overview map to the right marks this location, inside the Medusa Fossae Formation, the largest volcanic ash deposit on Mars. The many parallel north-south ridges that the river system cuts across are likely ancient dunes of this volcanic dust, now solidified and being worn away. Whether the ash fell first, then the river flowed through it, or the river was created, turned into ridges, and then the ash followed, is not obvious from the visibile data. All we can see with certainty is the terrain looks old and corruded, with few craters.
We are looking at a window into the far Martian past, uncovered by erosion caused by the endless winds of Mars, weak as they are.
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
Cool image time! The picture to the right, cropped and reduced to post here, was taken on August 27, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It was featured by MRO’s science team yesterday, in which Shane Byrne of the Lunar and Planetary Lab University of Arizona wrote the following:
River beds often get filled with gravel and the surrounding terrain is often built up of fine-grained mud from river overflows. The gravely river bottom and the fine-grained surroundings can lead to a strange phenomenon that geologists call inverted channels. After the river disappears, the fine-grained surroundings can be easily eroded away leaving the gravely river bed as a high-standing ridge.
These ridges show the location of the old river beds in Mars’ distant past. The angle at which the ridges join together indicate that these rivers flowed from top-right to bottom-left (i.e. southwest).
The picture above is a mosaic produced from the global survey taken by MRO’s lower resolution context camera. It gives us a fuller picture of this river system, with the rectangle showing the small area covered by the photo on the right. Overall this ancient and extinct river of ridges travels more than thirty miles downhill from the northeast to the southwest.
The white dot on the overview map to the right marks this location, inside the Medusa Fossae Formation, the largest volcanic ash deposit on Mars. The many parallel north-south ridges that the river system cuts across are likely ancient dunes of this volcanic dust, now solidified and being worn away. Whether the ash fell first, then the river flowed through it, or the river was created, turned into ridges, and then the ash followed, is not obvious from the visibile data. All we can see with certainty is the terrain looks old and corruded, with few craters.
We are looking at a window into the far Martian past, uncovered by erosion caused by the endless winds of Mars, weak as they are.
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
Inverted channels are nice, but I prefer incised meanders.