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Image Credit: THEMIS instrument. Image courtesy of NASA/JPL/Arizona State University.

Mar 19
, 2007
More Martian “Lava Tubes”

When planetary scientists see complex channel networks on Mars, they typically think of collapsed lava tubes. But now, it is the lava tube theory that is collapsing, under the weight of unjustified assumptions.

In considering the Martian surface features above, the first requirement is to see the network of depressions as depressions. For some observers this may require training the brain to recognize that the light is coming from the left.

The original caption to the above image released by the THEMIS team states unequivocally that “the deep channels likely began as subsurface lava tubes whose roofs collapsed as pits developed over them. Examples of this process are clearly evident throughout the scene. Also present are relatively straight graben that crosscut many of the channels and pit chains.”

It is dismaying to see how routinely planetary scientists ascribe channels and chains of craters on the Martian surface to “collapsed lava tubes.” But their limited tool kit allows for no other explanation. In the same way, steep parallel-walled “sunken” terrain that doesn’t fit into the “collapsed lava tube” theory is, with no attention to anomalous details, attributed to faulting and labeled as “graben.” From the caption noted above, it does not appear that the awkward intermingling of categories caused NASA scientists to pause and look more closely.

But is there evidence of any collapse at all in these images? Many of the Martian features are shallower than would be expected from a collapsed roof of a lava tube. And where is the rubble? The floors of collapsed lava tubes on Earth invariably display heaps of jagged debris. Where are the caves opening to the underground “tubes”? Thousands of similar channels and crater chains can be observed on Mars, but we have found only one arch and no openings to the underground vents that the explanation requires. (If any reader of this piece knows of an exception, we would be grateful for a correction.) The common feature of collapsed lava tubes on Earth is the cave allowing visitors to peer into that part of the tube which has not collapsed. See “The Moon and its Rilles (2).”

Geologists define a “graben” as the subsidence of a surface due to parallel faults. In the picture above, the direction of the supposed “grabens” is noted by blue arrows. Is there any useful terrestrial analog that would justify a theory of grabens and collapsed lava tubes superimposed in this way? By all appearances, the processes creating the one neither affected, nor were affected by, the existence of the other. Either pre-existing grabens were incapable of deflecting the flow of lava, or the lava flowed uphill and downhill, ignoring gravity. We also see an abundance of “lava tubes” intersecting and overlapping in ways that critical-minded observers, giving attention to detail, will surely see as preposterous.

Our knowledge of collapsed lava tubes came from the geology of our own planet. But where on Earth do we see anything remotely like this tangled network of “lava tubes”?

With the advent of the HiRISE project, NASA will have plenty of opportunity to look at the terminations of candidate channels from angles that will provide a good view into the theorized caves—if they are there. While we are not ready to make categorical predictions, we suspect they will be consistently disappointed. And when it comes to the depressions imaged above, we confidently stand by the prediction that no openings will be found, no matter how closely HiRISE scrutinizes the region. Many terminations are clearly visible, and they are constituted of sharply and smoothly cut cliffs, with no openings to caves.

For such anomalous features on Mars we have given the name “pits, scoops, and gouges,” to emphasize an undeniable implication: material has been removed by forces acting on the surface from above. We do not believe it is rational to ignore the one force—electricity—which, acting on a surface from above, can remove material to produce the very observed patterns: scooped out depressions, crater chains, and extended channels. Though it can be very difficult to get planetary scientists to consider the role of cosmic currents in the past, a thousand different evidential threads do, in fact, point in exactly the same direction.

But if misdirection in planetary science is occurring at the scale we believe, the problem will require at least a few investigators to look more deeply.

Thanks to Michael Gmirkin for much of the factual content in this submission.

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