Saturday, November 29, 2008

Bringing Geology to Life (Literally)

For those of us who thought rocks were inanimate, or that the only link between rocks and life was that of substrate, it's time to think again. Rocks (or at least, minerals) are not life's silent partner. Rocks and ecosystems have a sort of dialogue. A Texas Two-step.

This is a discovery termed "breathtaking" by Stanford University geologist Gary Ernst.

Carnegie Institution's mineralogist, Robert Hazen, is the lead researcher in the study. Hazen, a scientist of impeccable and long repute, has tracked the evolution of minerals through geologic time. His inquiry began, he notes, when a colleague asked "Were there clay minerals in the Archean?"-- a time period that began 4 billion years ago or so.

Only a dozen or so minerals --mostly simple metals or metal compounds-- are considered "Primordial" with such basic structures that they are among the first solid compounds formed in nebulae. Iron. Nickel. Copper.

Meteorites--the stuff of the early, inanimate universe 4.6 billion years or more ago--contain a grand total of only 60 minerals and had to undergo the heat and pressures of planetary agglomeration to form. Most, in stony meteorites (Chondrites) are the kind of basic material that we learned in Geology 101. Olivine. Pyroxene. Feldspar.

Fast-forward to the start of Earth's plate tectonics 4.2 billion years ago. More mineral varieties appear. as water, heat and pressure become more available . The total of likely minerals at the start of Plate Tectonics blossoms to 250.

Life appears on the scene at 4 billion years, give or take a few days. And the number of minerals blossoms. At the end of the Archean, marked by the appearance of oxygen and the invention of photosynthesis, Hazen and his colleagues can count 4300 minerals. They include clays, hydrated minerals, and a whole bunch of compounds that never made it to your mineral ID tray. What life seems to be doing is crafting new niches and pressure/temperature conditions ... and minerals, bless their little stony souls, seem to be adapting.

The point is that as biological complexity has increased, so has mineralogical complexity. Rate development of new varietys of minerals increases a hundred-fold once life gets into the act. The linkage is so clear that Hazen uses the term "Co-evolved."

He is not the only venerable scientist to recognize the link between planet and life. At the University of Chicago, mineralogist Joseph Smith has long seen minerals as catalysts for biochemical change. University of Glasgow scientist Graham Caims-Smith argues that clays--the actual silicate minerals--developed into the first life forms. (While this is reminiscent of several Star Trek episodes, there is also a long and honored tradition of Science being even stranger than science fiction.) Caim-Smith's rationales for clay minerals as very early templates for what would later become carbon-based life are taken very seriously by those scientists tracking the origin of life.

Rocks may seem solid and unfeeling, and we have yet to ascribe emotions to them. (Although "stony silence" comes to mind...) But there is now no question that the link between life and geology is vital, and that it is a two-way street. We interact. Slowly, but we interact.

We are co-evolved.

Geology is sometimes seen as a second-class science. Not very relevant to life. Not very dynamic (unless there's an earthquake or a Mt. St. Helens.) But now there's a clear link to life science as well as physical science. It is a sort of Renaissance. And at least a recognition of what geologists innately recognize. Life rocks.

Rock on!




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