Pennies Aplenty, Poisonous Ground, etc.

March 07, 2008

Here are three more jewels from the March issue of the Geological Soc’y of America’s journal Geology. For more info on these, check out the abstracts.

PENNY SUPPLY SAFE
The Earth’s total estimated extractable copper has now been calculated. According to the University of Michigan’s Stephen Kesler and Syracuse University’s Bruce Wilkinson, there is enough copper to keep humanity rolling in pennies for another 5,500 years, at the current rate of copper consumption.

DESERT ‘PAVEMENT’ HIDES POISON
Some of the oldest ground in the world is what’s called desert pavement – flat areas of desert ground where erosion has pieced together a remarkably flat (and fragile) layer of small stones. The University of California at Riverside’s Robert Graham and his colleagues have discovered that beneath these pavements the deserts are hiding a remarkable amount of nitrate – something that’s used as fertilizer in other places. The discovery could mean there is up to five times the nitrate in desert soils than previously believed – a huge up-tick in the global nitrate inventory. Unfortunately, off-road vehicles are ripping up desert pavements in places like the Mojave Desert and reactivating erosion – getting that nitrate back into circulation again. That’s bad news for local water supplies, since nitrate is not good for human health.

SCRAPED UP MOUNTAINS
Ever have to clean up the edge of a spatula? You know that crusty edge of dried up food? Well that’s sort of what Alaska is in a plate tectonics sense. The state is bounded to the south by a collision is plates, with the North American side to the north sometimes scraping mountains, volcanoes and other geological flotsam, off the subducting oceanic plates smashing it all onto the mainland. In the process of all that smashing, the mainland itself has felt the pressure of the collisions. All of this and more is explained in a paper by the U.S. Geological Survey’s Gary Fuis.