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Dry Martian chaos

Dry chaos on Mars
Click for full image.

On Mars, one of the most common kinds of landscape is called chaos terrain. Made up of mesas, buttes, and cross-cutting random canyons, this geology is not seen on Earth, and when first identified by scientists in early orbital pictures in the 1970s, it baffled them. While it is clear that some form of erosion process caused it, the scientists did not have enough data then to figure out what that process was.

Today scientists have a rough theory, based on what they now know about Mars’ overall geology and its climate and orbital history. The canyons of chaos terrain were originally fault lines where either water or ice could seep through and widen. See this January 2020 post for a more detailed explanation.

Most of the cool images I have posted of chaos terrain have been in places in the mid-latitudes that are covered with glaciers. See for example this December 2019 post of one particular mesa in glacier country, with numerous glaciers flowing down its slopes on all sides. That mesa is quite typical of all such mesas in the mid-latitudes.

Today’s cool image above, cropped to post here, takes us instead to the Martian very dry equatorial regions. The photo was taken on May 17, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO), and like mid-latitude chaos, it shows a collection of random mesas with canyons cut almost randomly between.

Unlike the mid-latitudes, however, there is no evidence of glaciers here. Instead, the canyons and mesa slopes are covered with dust, shaped into wind-blown dunes.

As always, the overview map below gives us some context.

Overview map

The white cross marks the location of today’s image. Located in a chaos region dubbed Iani Chaos, this region is just south of the upstream end of the 1,100-mile-long meandering canyon dubbed Ares Valles. If water or ice once flowed down Ares Valley, it likely came out of Iani Chaos as it carved its canyons and buttes.

In trying to understand the geology in MRO photos, I am finding it increasingly amazing how helpful it is to know the latitude. When something is above 30 degrees latitude you will almost always see some evidence of near surface ice, either from an underground ice table or as buried glaciers.

Below 30 degrees latitude you will instead see no such evidence. Instead, the landscape will — like today’s photo — appear very dry, with the ground either hard bedrock or covered with dust and dunes. (See these two recent posts here and here for similar examples.)

That the nature of the Martian surface is so well determined by latitude is actually one of the more important discoveries scientists have uncovered about Mars in the past two decades. It not only tells them what to expect in each image, it provides some fundamental clues into the entire geological history of the red planet.

That history is not yet completely deciphered, but knowing this one simple fact will make finding the solution much easier.

Conscious Choice cover

Now available in hardback and paperback as well as ebook!

 

From the press release: In this ground-breaking new history of early America, historian Robert Zimmerman not only exposes the lie behind The New York Times 1619 Project that falsely claims slavery is central to the history of the United States, he also provides profound lessons about the nature of human societies, lessons important for Americans today as well as for all future settlers on Mars and elsewhere in space.

 
Conscious Choice: The origins of slavery in America and why it matters today and for our future in outer space, is a riveting page-turning story that documents how slavery slowly became pervasive in the southern British colonies of North America, colonies founded by a people and culture that not only did not allow slavery but in every way were hostile to the practice.  
Conscious Choice does more however. In telling the tragic history of the Virginia colony and the rise of slavery there, Zimmerman lays out the proper path for creating healthy societies in places like the Moon and Mars.

 

“Zimmerman’s ground-breaking history provides every future generation the basic framework for establishing new societies on other worlds. We would be wise to heed what he says.” —Robert Zubrin, founder of founder of the Mars Society.

 

All editions are available at Amazon, Barnes & Noble, and all book vendors, with the ebook priced at $5.99 before discount. The ebook can also be purchased direct from my ebook publisher, ebookit, in which case you don't support the big tech companies and I get a bigger cut much sooner.

 

Autographed printed copies are also available at discount directly from me (hardback $24.95; paperback $14.95; Shipping cost for either: $5.00). Just email me at zimmerman @ nasw dot org.

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