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.

A chain of Martian sinkholes

Chain of sinkholes on Mars
Click for full image.

Cool image time! The photo to the right, rotated, cropped, and reduced to post here, was taken on June 17, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows a somewhat straight depression with several wider and deeper pits along it.

The feature immediately suggests sinkholes that exist because the ground is sagging into voids below ground. Yet, both the straight and circular depressions also appear filled, showing no evidence that they connect to any below ground cavities.

Are the sinks the result of a fissure produced by a graben, when two large blocks shift relative to each other to cause a fissure to appear? Or are they evidence of an underground lava tube? Or maybe they are the filled remains of a now mostly buried canyon carved by water or ice?

As always, a wider view helps clarify things, though whether it answers the question is uncertain.

Overview map

Mosaic of two MRO context camera photos
To see full images, go here and here.

The overview map to the right, with the photo’s location indicated by the white rectangle, shows that this depression is located in the Tharsis Bulge, the region on Mars where its largest volcanoes are found. To the southeast is Ascraeus Mons, Mars second largest volcano, about 600 miles away. To the west about 1,900 miles away is Olympus Mons, Mars’ largest.

Thus, the feature is not likely a flow feature carved by water or ice. The altitude is too high, almost all the geological features here are volcanic, and the latitude, 17 degrees north, is in the Martian dry equatorial regions where little evidence of surface water or ice is found.

The second image to the right, created by me from two MRO context camera images, shows a wider view of this region. The black rectangular marks the area covered by the photo above.

As you can see, there are two pit chains in this area. They are parallel to each other but also appear have formed separately. Based on the lobate flow to the northwest that resembles very much frozen lava, both chains run in a direction that seems at right angles to the downhill grade.

Based on the wider images and the location, my guess therefore is that these depressions signal a graben, fissures created along a fault. The sinks suggest that the fissures are not entirely filled, but have some voids below in which the surface dust and debris is sinking.

What is most puzzling about these features is their isolation. If formed from faults, you would expect the faults to be more extensive. Instead, the two cracks are relatively small features on a smooth flat lava plain.


Please consider donating to Behind the Black, by giving either a one-time contribution or a regular subscription, as outlined in the tip jar below. Your support will allow me to continue covering science and culture as I have for the past twenty years, independent and free from any outside influence.

Your support is even more essential to me because I keep this site free from advertisements and do not participate in corrupt social media companies like Google, Twitter, and Facebook. I depend wholly on the direct support of my readers.

You can provide that support to Behind The Black with a contribution via Patreon or PayPal. To use Patreon, go to my website there and pick one of five monthly subscription amounts, or by making a one-time donation. For PayPal click one of the following buttons:


Or with a subscription with regular donations from your Paypal or credit card account:


If Patreon or Paypal don't work for you, you can support Behind The Black directly by sending your donation by check, payable to Robert Zimmerman, to

Behind The Black
c/o Robert Zimmerman
P.O.Box 1262
Cortaro, AZ 85652

One comment

  • Greg the Geologist

    Cool and very curious for sure! Another puzzling aspect is the clear wind-driven dunes in the depressions (maybe graben), and the streaks on the mesa just south of the linear depression, indicating wind generally west-to-east. Then on the surrounding mesa, the only features that appear wind-shaped are the many very small linear structures oriented north-northeast. Not sure what they could be.

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.

Leave a Reply

Your email address will not be published. Required fields are marked *