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Black Canyon City quake locations refined; seismograph recording posted

We have updated the locations of last nights earthquakes near Black Canyon City, using the Arizona seismic stations in the AZGS network.Jeri Young also passed along this shot of the seismic signals received by the nearest station in our network, Strawberry/Payson X16A, about 65 km east of last night's quakes. Show More Summary

Earthquakes north of Black Canyon City shake up much of Arizona

Notable earthquakes with magnitudes of 4.0 and 4.1 hit a few miles north of Black Canyon City around midnight Sunday, with a foreshock of magnitude 3.2 at 9 pm [top, location map from USGS] Dr. Jeri Young, who manages the seismic monitoring...Show More Summary

A Series of Hopefully Fortunate Events: Saying Goodbye to Yosemite's High Country (for now)

Our field studies trip to Yosemite National Park reached a climax when we reached Tioga Pass (9,943 ft / 3,031 m) at the east end of the park. The pass is the highest highway route in the state (a paved road in the White Mountains and the Bristlecone Forest reaches just a few feet higher, at 10,075 feet). Show More Summary

Update from the Lake: It's Fall Again!

It's been a slow fall, it seems, and when I went out looking for brightly colored leaves yesterday, I didn't find all that many. One reason is that we've cut down all the aspen trees: they take over the yard and block the sun from our newly planted fruit trees and berry bushes ("newly" being in the last couple years). Show More Summary

Meteor breakup over Tucson

Heading off to the airport this morning at 5:18 a.m. I watched two bright lights in the southwest sky moving to the southeast. The front light was orangish and the rear one yellow. They were moving faster than planes normally do which is when I realized the pair were meteorites on the same path. Show More Summary

A Series of Fortunate Events: Climbing a Dome That's Not Exactly a Dome...It's Rock Mutton

There are domes and there are "domes". Yosemite National Park has a lot of domes of one sort or another, and there has always been a bit of confusion about their origin. From various points in Yosemite Valley, one can spy at least four them, famous Half Dome, less famous Sentinel Dome, North Dome, and Basket Dome. Show More Summary

A Hike Up Glass Mountain

It was Earth Science Week, and a relatively small group of Nevada geologists went on a two-day field trip to a couple places that included Medicine Lake volcano. Here we are beginning a half mile hike to an overlook point on Glass Mountain,...Show More Summary

New report on Cordilleran tectonics likely to generate its own upheaval

A new paper published today is bound to generate heated debate. Tucson-based geologist Robert "Bob" Hildebrand's article " Dismemberment and northward migration of the Cordilleran orogen: Baja-BC resolved" came out in GSA Today with a provacative conclusion. Show More Summary

Finding a Thesis: A Bit O' Geology in the Palmetto Mountains

My (very) rough interpretation of the Walker Lane on Google Earth. As for the broad geology of the Palmetto Mountains area, what I knew back in the spring or early summer of 1976 was quite broad, and it probably wouldn't have filled up the trunk of my '72 Opel. Show More Summary

Oakland’s conglomerate cousin

Before I begin, let me repeat last week’s announcement inviting you to take part in the blog study. It ends October 31, so this is the last week. A bunch of you have participated already, which is great. This time I left the exclamation points off the script — I predict that will boost the […]

A Series of Fortunate Events: Why Settle for Half a Dome When You Can Have a Whole One?

Imagine standing at one of the most famous park viewpoints in the world. Ask people standing in that place, the Wawona Tunnel Overlook at Yosemite National Park, how many granite domes they see, they might say just one. If they're feeling humorous, they might even say not just one, but half of one (let's discuss that point). Show More Summary

Picture Yourself Here: Multidisciplinary Field Studies in the Hawaiian Islands, June 1-13, 2016

This might be of interest only to my Modesto area readers, but anyone who is interested in learning about the natural and human history of the Hawaiian Islands may want to investigate this field studies opportunity June 1-13, 2016. I...Show More Summary

A Series of Fortunate Events: Glacier Point, Living Up to the Hype

Glacier Point on the rim of Yosemite Valley is hands-down one of the most spectacular places one can stand in the world. There's just no place like it. And it's noisy. It's crowded. There is a busy and often full parking lot. And despite...Show More Summary

Finding a Thesis: Farther into the Palmetto Mountains

Magruder Mountain from Lida Summit. The sun went down on that 1976 campsite perched somewhere on the south side of the Palmetto Mountains, and I eventually fell asleep, curled up in my barely adequate sleeping bag on the ground near my '76 Opel. Show More Summary

A Series of Fortunate Events: Is it Time to Rename Half Dome?

We spent three days exploring the geology of the Yosemite region last week, and the first stop on Saturday was Washburn Point, an amazingly quiet viewpoint given its proximity to Glacier Point. It's a parking lot, sure, but no bathrooms, no curio or snack shops, few interpretive signs, and in my experience it is far less crowded. Show More Summary

A Series of Fortunate Events: Chasing Away the Ghosts of Nelder Grove

Not much can kill them. And once they've been killed, it takes a long time for them to go away. There's one in the picture above, can you see it? No, this isn't a post about zombies, it's a story about Giant Sequoia trees (Sequoiadendron gigantea), a tree with a geologic story. Show More Summary

Two lessons about floods (and a survey)

As we anticipate the strong possibility of heavy El Niño rains, my attention will be on Oakland’s streams this winter. Last week parts of southern California were hit by “thousand-year” rainfall events, cloudbursts that washed thick sheets of mud over roads and properties. We can expect such things here too, in any given thousand-year period. […]

Tuolumne River Trail Nears Completion: A Short Explore Along a Priceless River

The value of a river can be measured in so many ways, and the Tuolumne River here in California is no exception. It has headwaters in the spectacular high country of Yosemite National Park, flows through a gorge as deep as the Grand Canyon, gets trapped for a time in Hetch Hetchy Reservoir, and later in Don Pedro Reservoir. Show More Summary

A Series of Nearly Unfortunate Events: Fall in Yosemite National Park

Oh jeez, that's not something one likes to see on a field trip... How many horror movies begin with people ignoring the warning signs, both literally and metaphorically? The doomed characters doggedly soldier on, minor disasters mount, and then major disasters. Show More Summary

Debris flows (mudslides) worsened by wildfires - expect more across the West

Yesterday's mudslide (actually debris flows) on Interstate 5 in southern California were a result of a huge El Nino storm over grounds laid bare by intense wildfires and hardened to runoff by drought.With predictions of the biggest El...Show More Summary

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