Signs of volcanic activity are widespread within the Chihuahuan Desert. Lava flows, cinder cones, and ash flows remain to remind us of this part of our prehistory. Not that all of this was that long ago—the Valley of Fire flow in southern New Mexico is only a few thousand years old. We can be forgiven if we think solely in terms of volcanic rocks as the result of volcanic eruptions. But think of pictures we've seen of erupting volcanos—something else also is at work. What's driving those immense clouds of ash thousands of feet into the air? Gases, of course. Gases coming out of solution as the lava reaches the surface, propelling tons of melted rock skyward.
These gases may be more than just propellants, though. While water
vapor typically is the most abundant gas, carbon dioxide, sulfur dioxide, hydrochloric
acid, and hydrofluoric acid may be represented, among others. It's been suggested
that widespread eruptions accompanied by vast amounts of carbon dioxide may be behind
some global mass extinctions. Volcanos produce much more than lava and ash!
Contributor: Arthur H. Harris, Laboratory for Environmental Biology, Centennial Museum, University of Texas at El Paso.
Desert Diary is a joint production of the Centennial Museum and KTEP National Public Radio at the University of Texas at El Paso.
Keppler, H., M. Wiedenbeck, and S. S. Shcheka. 2003. Carbon solubility in olivine and the mode of carbon storage in the Earth's mantle. Science, 424:414-416.