Thursday, August 20, 2009

Geological Conservancy?




Andrew Alden, as he often is, is right on top of a great idea, a proposal for a Geological Conservancy, modeled along the lines of the well-known Nature Conservancy, and less well-known groups like the Archaeology Conservancy. The proposal is outlined in some detail here, in the SIPES Quarterly. I think the idea is well worth exploring. So many geologically significant outcrops and roadcuts lie outside of national parks or monuments and are constantly threatened with destruction. Roadcuts are especially vulnerable, as road maintenance crews are often ignorant of the importance of the rock faces under their care. I've illustrated three famous sites in California that fall into this category.

The first is the Shoshone Roadcut, often referred to as the Charlie Brown Outcrop (the Charles E. Brown Highway). It illustrates in a wonderful manner the relationships of extensional faults and ash flow tuffs/air fall tuffs in the Basin and Range Province. The surrounding lands are administered by the Bureau of Land Management.

The second picture is the Sherwin Summit roadcut (the "Big Pumice Cut") that settled the question of the age of the Sherwin Glaciation of the Sierra Nevada in relation to the well-dated eruption of the Bishop Tuff. It is a cherished outcrop to legions of California geology students, but at various times road groomers have threatened to cover the outcrop with vegetation, or alter itto a great degree. I believe the land behind the outcrop is managed by the U.S. Forest Service.

The third photo is one of our local special outcrops, where quartz and mariposite veins of California's Mother Lode cross a major highway near Coulterville. The site illustrates the relationships of the ores with the surrounding metamorphic rocks which formed within a subduction zone complex in Mesozoic time. One would need access to an underground mine to have an equivalent view of these complex relationships. The land back of the highway is privately owned.

These kinds of outcrops don't have the natural constituency that places under the protection of the Nature Conservancy often have. They are not always scenic, and they generally don't form a critical habitat for rare plants or animals. But they do offer an invaluable educational experience for learning the basic principles of geology. They should have some form of protection, and a conservancy might be a good approach.

I worry a little about publicizing some of these places, though. Outside Las Vegas, at Frenchman Mountain, the UNLV geology department spent years and lots of money on building some wonderful monuments describing the Great Unconformity between Proterozoic gneisses and Cambrian sandstones. They were vandalized almost right away, and people continue to dump rubbish in the canyon (the site is periously close to a tsunami of housing developments on the northeast side of the city).

What do you think? Is this worth pursuing? How has the ability and resources to administer such a program?

What kinds of places exist in your area that deserve some kind of recognition and protection that they are not receiving now?