[aerohead]

I just finished an 8-page, 7-graphic, article: ' The Rio Grande Rift', by Scott Baldridge and Kenneth H. Olsen, The American Scientist, Volume 77, May- June, 1989, 43-references, 85-scientists, spanning researches from 1953-to- 1989.
The Rio Grande Rift originates in Colorado, an spans New Mexico, Texas, and into Northern Mexico, and is the largest rift zone in the United States, topologically dwarfing the Grand Canyon, if all alluvial sand, gravel, and rock removed.
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In the references, one stood out: 'Convective thinning of the lithosphere: A mechanism for rifting and mid-plate volcanism on Earth, Venus, and Mars,' by T. Spohn and G. S. Schubert, Tectonophysics 94:67-90, 1983.
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With respect to Valles Marineris, some of the geological mechanisms attributed to its creation are :
* early volcanism
* lithospheric stretching
* plate rupture
* overprinting
* extensional deformation
* grabens
* subduction
* lateral shear
* transform motion
* vertical faulting
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Any mention of lightning being associated with creation of the feature is conspicuously absent.