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7 December 2022

The coastal section at Esterillos Oeste, Costa Rica

Callan documents a geological stroll along the coast of Esterillos Oeste, in central southern Costa Rica, investigating the sequence of sediment in the Punta Judas Formation (Mid-Miocene) exposed there. Fossils, sedimentary structure, diagenetic features, structural deformation, and modern weathering all make prominent appearances.


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3 April 2020

Friday Fold: Saudi Arabia

The Friday fold is a guest post from Wadi Fatima, in Saudi Arabia.


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14 February 2020

Friday fold: Miocene slump in Anza-Borrego

Today’s Friday Fold comes from Edith Carolina Rojas, the dynamic geology professor at The College of The Desert in Palm Desert, California. She’s an awesome person, and also the sense of scale in this amazing image: Edith shares that this gorgeous structure is an anticline is located in Split Mountain Gorge in Fish Creek Canyon. It’s a gigantic gravity-slide fold due to soft sediment deformation in the Latrania Formation. Wow …


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10 November 2017

Friday fold: soft sediment deformation in California’s Castaic Formation

The guest Friday fold comes to us from the Miocene of California, deposited in a releasing bend basin along the San Andreas Fault.


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2 June 2016

Flood deposits of Glacial Lake Missoula outburst floods

Two weeks ago, I went on an awesome, informal field trip to eastern Washington State to visit the Channeled Scablands for the first time. My collegue Bill Richards of North Idaho College picked me up in Spokane and drove me halfway across Washington and back to Moscow, Idaho, over the course of a day. This is a region of the country where a glacier-dammed valley filled up with water (Glacial …


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18 May 2016

Pillow basalt exposures in the Columbia River basalts

Pillow basalts form when mafic lava erupts underwater. Here are several examples from the Miocene Columbia River flood basalts, a large igneous province in eastern Washington state.


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17 May 2016

Spheroidal weathering in Columbia River basalt

I’m in Idaho for the Rocky Mountain section meeting of the Geological Society of America. Yesterday, I was delighted to tour around in eastern Washington’s Channeled Scablands with my colleague Bill Richards (North Idaho College). I took a lot of photos, but here are two to start – lovely examples of “onion skin” style weathering in fractured basalt, producing “kernstones” of increasingly spherical shape: This is a particularly well expressed …


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29 May 2015

Friday fold: Hayward neighbor

The Friday fold is some crumpled sedimentary rock near the Hayward Fault in California.


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5 March 2013

Documenting doomed outcrops: Scientists’ Cliffs, Maryland

The community of Scientists’ Cliffs in Maryland is a private community that happens to sit on some of the most amazing fossil exposures in the Coastal Plain. The strata in question are part of the Miocene-aged (~14 Ma) Calvert Formation. The Scientists’ Cliffs outcrops are better than the more famous outcrops at Calvert Cliffs State Park, mainly because of easier access. At the park, you have to hike in a …


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29 October 2010

Geology of the Richmond area field trip

On Saturday, after a fruitful 24 hours at the VCCS Science Peer Conference, my colleague Pete Berquist (of Thomas Nelson Community College) and I led a field trip to examine the geology of the Richmond, Virginia, area. We were joined by seven of our VCCS science-teaching colleagues and author Lisa Starr, a speaker at the conference. We started off by driving down to Belle Isle, an island located on the …


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