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25 June 2018
Sonora Pass, California, is a lovely place to examine a volcanic-on-plutonic nonconformity that spans about 80 million years of missing time. Let’s check it out on a photo-rich virtual field trip!
23 June 2018
Fifteen years after mapping deformed rocks of the Sierra Crest shear zone system in the high Sierra, a family vacation brings Callan back to the pre-batholith metasedimentary rocks which show a pronounced strain.
19 August 2016
My friend Bill Burton (USGS, Reston) shared today’s Friday fold — Chevron folds in marble, Kings Canyon, California. Nice! Thanks for sharing, Bill!
27 February 2013
The Accretionary Wedge is a ~monthly geoblog “carnival” which elicits posts on a variety of themes. This month, it’s Maitri’s turn, and she wants to hear about our geo-injuries. Here’s my story: In 2003, I was doing field work in the high Sierra, mapping the Sierra Crest Shear Zone for my geology master’s degree. When I first got out there that summer, Scott Paterson of the University of Southern California …
24 November 2012
The Boulder Batholith outside of Butte, Montana, is actively weathering, and shedding off grus. In the third installment of the Transitions of the Rock Cycle series, we watch an igneous rock turn to sediment.
20 March 2012
I’ve been showing a lot of photos lately from my field course’s trip up into the White Mountains. While we were driving up the road from Westgard Pass to the Ancient Bristlecone Pine Forest, we saw something interesting going on in the southern Owens Valley. Take a look at this view to the southwest, from the overlook: See it, way there in the distance, but between the photographer’s vantage point …
16 March 2012
Callan and his field studies students encounter a lesson in the White Mountains of eastern California that combines bedding, cleavage, folding, and even fossil archaeocyathids!
7 March 2012
Sunday was our first full day in the field. Here’s a few looks at my NOVA students doing geology out in eastern California. We spent the day on, and next to, the Volcanic Tableland north of Bishop, a massive stack of ash fall and ignimbrite deposits erupted from Long Valley Caldera 760,000 years ago: the Bishop Tuff. Climbing the southern edge of the Volcanic Tableland from the erosional valley of …
4 April 2010
Searching through my photo archives this morning for something suitably “Eastery”… something in pastel colors, perhaps? … a petrified lagomorph? … how about an egg, or something egg-shaped? This is as close as I got: This is in the Owens Valley of eastern California, showing a boulder of the Mesozoic Sierra Nevada Batholith bearing a faulted xenolith. I love outcrops like this, with a combination of primary structures (like the …
2 April 2010
A quick post to share a few images of an outcrop I visited last September out in California’s Owens Valley. This is a spot where alluvial fans coming off the eastern Sierra Nevada were overrun by a basaltic lava flow (Jeff, Kim, Fred, and Kurt for scale): The unofficial term for these conglomerates deposited by alluvial fans is “fanglomerate,” and it’s pretty cool to see the contact metamorphism at the …