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.


New cracks across old Martian lava flows

New cracks across an old lava flow
Click for full image.

Cool image time! The photo to the right, cropped and reduced to post here, was taken on June 4, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It captures one of the many deep straight fissure canyons that make up the feature dubbed Cerberus Fossae in the center of Mars’ volcano country.

The crack is called a graben, and happens when the ground is either stretched from pressure from below, or when two adjacent large blocks of material move sideways relative to each other.

What makes this particular graben interesting are two features. First, the overlapping break suggests something complex took place at this spot when the crack separated. Second, the crack cut across the foot of an older frozen lava flow, meaning it has to be younger than that flow.

The overview map below provides a clue when that lava flow might have occurred, while also suggesting this crack in Cerberus Fossae might be much younger than expected.

Overview map

The white cross marks the location of this crack and flow, at the western end of Cerberus Fossae and just beyond the north edge of the Athabasca Valles flood lava, hypothesized by some scientists [pdf] to be the youngest large flood lava event on the Red Planet. They estimate it occurred less than 600 million years ago, covering an area about the size of Great Britain in only a matter of weeks.

This spot is also not far from another feature scientists think might be a volcanic eruption only 50,000 to 210,000 years old.

The location is also close to where InSight’s seismometer has detected its largest Earthquakes, as indicated by the white splotches on the map.

Moreover, for the cracks of Cerberus Fossae to cut across older features is not unusual. See this April 2021 cool image for just one other example.

All these facts strongly suggest that the crack itself is relatively very young. The abrupt steepness of the canyon walls as well as the sharpness of its rim further reinforces this supposition. If the fissure was old, there would have been time for the rim and canyon to soften.

This data thus suggests that some very dramatic volcanic events on Mars have happened in the relatively recent past. The underground pressure required to stretch and crack the surface as extensively as it has been in Cerberus Fossae is not trivial. More important, that there is accumulating evidence it is young means that large scale volcanism might very well still be active on Mars. Events might be well spaced out in time, but they can still occur.

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6 comments

  • Greg the Geologist

    “Overlapping” faults or graben can occur when the direction of stress is a few degrees off from a structural weakness in the rock mass (either from cooling fractures, or earlier faulting). Preferentially, the rock breaks according to those pre-existing weaknesses. But they will be overlapping, or ‘en echelon’ (geo term), conforming to the larger, regional stress field. With that said, what a spectacular view!

  • Greg the Geologist: Ah, thank you. That explains the overlapping cracks.

    What still intrigues me is how the data is increasingly suggesting the youth of Cerberus Fossae.

  • Andi

    Might I suggest that seismic events on Mars be referred to as “Marsquakes” or simply “quakes”? “Earthquakes” seems somehow out of place.

  • Andi wrote “Might I suggest that seismic events on Mars be referred to as “Marsquakes” or simply “quakes”? “Earthquakes” seems somehow out of place.”

    Second.

  • So there is to be no common term for the geological shaking of the ground (“earth”) on which one is standing — regardless of planet? That seems dumb. And who says that the “earth” in “earthquakes” refers to the planet Earth?

  • Andi

    I always assumed that if “Earth” was capitalized, then it referred to the specific planet. One solution, which may be confusing, is to use lower case for the generic term.

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