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I am now running my annual July fund-raising campaign to celebrate the twelfth anniversary of the establishment of Behind the Black. For many reasons, mostly political but partly ethical, I do not use Google, Facebook, Twitter. These companies practice corrupt business policies, while targeting conservative websites for censoring, facts repeatedly confirmed by news stories and by my sense that Facebook has taken action to prevent my readers from recommending Behind the Black to their friends.


Thus, I must have your direct support to keep this webpage alive. Not only does the money pay the bills, it gives me the freedom to speak honestly about science and culture, instead of being forced to write it as others demand.


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Mars: Are these eroding glaciers or impacts in lava?

Eroding lava or glaciers?
Click for original image.

Cool image time and a mystery! The photo to the right, cropped to post here, was taken on March 29, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO) of an 18-mile-wide crater in the southern cratered highlands of Mars. The full picture, dubbed “Steep Cliff,” was taken apparently to get a good view of the crater’s northern rim. The rim’s steepness suggests that the floor of the crater is significantly filled.

More intriguing however are the scattering of strange depressions about six miles south of the rim. What caused them? The crater’s location is in a part of Mars where it is not unusual to find both glacial features as well as flood plain lava. In fact, the crater’s northeast and southwest rims appear to have been buried by what appears to be flood lava. The northern rim’s shallowness also suggests the crater is well filled with flood lava.

However, the crater is also at 38 degrees south latitude, a latitude where planetary scientists have found lots of glacial features. Much of this crater fill could be glacial.

The overview map below illustrates this mystery.

Overview map

The white dot in the lower left marks the location of the crater. It sits in the Tharsis Bulge, where Mars’ biggest volcanoes are all located as well as at the southern edge of the giant lava flood plain Daedalia Planum, which had covered everything with lava when those volcanoes were active.

So, are these depressions places where a top layer of glacial ice sublimated away to reveal the flood lava below? The mounds on the floor of these depressions could be lava, as evidenced by other pictures of flood lava elsewhere on Mars.

Maybe instead the depressions are secondary craters from a more recent larger impact nearby. If so, then why are some of these depressions so distorted? Maybe these impacts allowed the upper layer of ice to erode over time, reshaping the craters and also creating traps where more glacial ice could accumulate. The mounds within these depressions — though possibly lava — also resembles glacial features seen in many other mid-latitude craters, adding weight to this theory.

There is no answer yet to these questions, only more questions. We will need to go there to really answer them.

Conscious Choice cover

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.


Available everywhere for $3.99 (before discount) at Amazon, Barnes & Noble, and all ebook vendors, or direct from the ebook publisher, ebookit. And if you buy it from ebookit you don't support the big tech companies and I get a bigger cut much sooner.

One comment

  • Greg the Geologist

    Another great image! Interesting material – notice the very small, very clean, obviously very young craters in the floor material. There’s little or no ejecta, like they were absorbed in soft substrate. And notice the odd-looking, almost serpentine deposit/structure/feature near the foot of the slope. Is it in place? Or something that rolled downslope? Good place for a geology visit!

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