Andrew Alden

Andrew Alden earned his geology degree at the University of New Hampshire and moved back to the Bay Area to work at the U.S. Geological Survey for six years. He has written on geology for since its founding in 1997. In 2007, he started the Oakland Geology blog, which won recognition as "Best of the East Bay" from the East Bay Express in 2010. In writing about geology in the Bay Area and surroundings, he hopes to share some of the useful and pleasurable insights that geologists give us—not just facts about the deep past, but an attitude that might be called the deep present. Read his previous contributions to QUEST, a project dedicated to exploring the Science of Sustainability.
The coastal region of northernmost California, including the Klamath Range shown here, is in the Cascadia subduction zone, America's geological analog of Sumatra. Photo by Andrew Alden

Our Corner of Cascadia

A moderate earthquake this week in northwestern California is a reminder that part of our state lies in Cascadia, our tectonic analog of Sumatra and Japan.

Concretions at Bowling Ball Beach. Photo by {link url=}portmanteaus{/link} under Creative Commons license.

Confounding Concretions

Not crystals, not meteorites and not fossils, concretions puzzle people who find them. Geologists find them only slightly less puzzling than the general public.

This solid vein of white mineral near Endeavour crater, up to 2 centimeters thick, has every appearance of the well-known mineral gypsum. NASA/JPL-Caltech/Cornell/ASU image.

A Most Earthly Mineral on Mars

The planet Mars tantalizes with its resemblance to parts of Earth. Now space geologists with their trusty field assistant, the rover Opportunity, have found gypsum veins there like those in our own countryside.