Andrew's Geology Blog

See three new pages in the Earth Art Gallery. I learned recently that those newfangled walls along highways—those ones that look like fake bedrock, because they are?—are the work of ... Read More

Earthquake swarms are mysterious, but usually not threatening. Living in northern California, I've seen lots of them—I even have played with them. But the March-April swarm in the Reno area ... Read More

A rock hammer is essential field gear for geologists—not just for breaking rocks, but for any number of other tasks, from hammering pegs into the ground to opening beer cans ... Read More

The National Science Foundation has a project in which the community of Earth scientists will figure out what the public needs to know about geology. You can take part. A ... Read More

A paper published in Science today reports a major improvement in the precision of the argon-argon dating method (see the press release). More formally known as the 40Ar-39Ar method, it's ... Read More

Welcome to The Accretionary Wedge, a blog carnival with a geological theme, hosted each month by a different geo-blogger. During the course of Earth Day, I'll be adding links as ... Read More

The new movie Expelled is, by all accounts, a creationist effort (with an ugly whiff of Adam and Eve's persecution in its title) claiming that heinous offenses are committed against ... Read More

Wouldn't you know, early Friday morning a light earthquake struck the southern Illinois-Indiana border area, a strike-slip event of magnitude 5.2. Being on the stiff North American craton and at ... Read More

It was 18 April 1906, 5:12 local time when the rumbling began. (Today that hour would be 6:12, shortly before sunup.) More than a full minute later, it was still ... Read More

Tufa towers are a sign of drastically changed climate. Tufa is a spongy kind of travertine, a calcium carbonate deposit formed as springs discharge groundwater into conditions that force the ... Read More

You've all been here before—in innumerable Hollywood movies and advertisements. You may even come here in your dreams. It's the iconic landscape of California's Red Rock Canyon State Park, just ... Read More

I don't announce every new picture I add to a gallery, but this conglomerate boulder I saw in the Tumey Hills last month was awesome, a rainbow of smooth river ... Read More

A tiny island in narrow, scenic Tomales Bay has an even tinier islet nearby. At low tide a charming gravel path emerges between them: a tombolo. For this scene right ... Read More

At a press conference the morning of 14 April, a government task force put the official 30-year odds of an earthquake somewhere in California of at least 6.7 magnitude—the size ... Read More

After getting a few more photos in the field, I'm ready to present this gallery of the basic types of volcanoes found on land. It appears that there are eight ... Read More

A while back I named Planet Earth, by the late Cesare Emiliani, as my by-far favorite geology textbook, but lamented that it was probably an orphan title because the author ... Read More

I went to UC Berkeley today to hear Roland Bürgmann give this year's Lawson Lecture on the Hayward fault, "A Tectonic Time Bomb in Our Backyard." However, it happened yesterday. ... Read More

Earthquake prediction has a long history of fraud, failure and hysteria. If you stop the average seismologist on the street and bring up the subject, he or she will shout ... Read More

Last December at the AGU meeting, I ordered an earring made with this wonderful red fossilized dinosaur bone, and they threw in an extra piece for good measure. Take a ... Read More

OK, my photo processing is finished for now, and here's a master gallery devoted to Las Vegas geology. It includes side trips to other new galleries, the ones on Upper ... Read More

Not an exercise machine, it's the geologic mega-feature I kept seeing during my recent visit to Las Vegas and surroundings. The Sevier belt is a long zone where, during the ... Read More

Photos from a memorable visit to Valley of Fire State Park, Nevada, are ready for your viewing. (You can find the gallery in the Nevada Geology category, under Regional Geology.) ... Read More

An advanced x-ray imaging technique has pulled wonderfully detailed pictures of fossilized insects from pieces of opaque amber. The high-intensity x-rays are made at the European Synchrotron Radiation Facility (ESRF) ... Read More

Only 10 days ago, I was wandering the dry floor of this desert riverbed on the northern edge of Las Vegas, hunting for fossils. I saw no bison horns sticking ... Read More