Welcome to D.C. for #AGU2018
A summary of resources to learn about the geology of Washington, D.C. and the surrounding region, in anticipation of AGU’s Fall Meeting being held in the nation’s capital city.
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Friday fold: loopy limestone in Utah
The countryside near Provo, Utah yields a terrific Friday fold in an outcrop of Cambrian limestone.
Brittle overprinting ductile in the South Mountains metamorphic core complex, Phoenix, Arizona
Today, we take a look at the structural geology that reveals the deformation evolution (first ductile, then brittle) of the South Mountains metamorphic core complex, south of Phoenix, Arizona. Expect lots of photos of smeared-out rocks, broken by faults.
Flow banding in pseudotachylyte, South Mountains, Arizona
Watch the flow of frictional melt in a “fossil earthquake,” frozen in time atop the South Mountains metamorphic core complex in Phoenix, Arizona.
Friday folds: more deformation from Cinque Terre, Italy
A return to coastal Italy on this wintry Friday… You’ll recall that The Other Callan shared some fold imagery with us a few weeks back as he explored the Cinque Terre region of Italy. He is back in the States now, and has been kind enough to share his geology-themed photos with me, so I … Read more
Friday fold: Refolded marble from Corsica
The Friday fold comes to us from Corsica via University of Washington structural geologist Darrel Cowan. It’s a marble that’s been folded *twice!*
Friday fold: the Brooks Range, Alaska
It’s Friday, thank goodness. Today our “Friday fold” feature heads north, way north, to the Brooks Range of Alaska. There we find a trio of mountainsides exposing folds photographed in the 1990s.
Friday fold: the Devil’s Backbone and its neighbor
It’s Friday; time to stretch our backbones out in anticipation of the weekend. Let’s look to a backboney-named Friday fold for a little inspiration… …And what’s that, just down the road? Another fold, in need of a catchy name…
Q&A, episode 6
A reader asks about Callan’s source of inspiration, a fitting question given the advent of Earth Science Week, which this year has as its theme “The Earth as Inspiration.” Brace yourself for a tantalizing cavalcade of gorgeous images of patterns in rocks!
Friday fold: Big Cottonwood Fm., Slate Canyon, Utah
It’s Friday and that means it’s time for a fold. Today we head to Cottonwood Canyon, Utah, with reader Octavia Spencer, for a lovely antiform.
Friday fold: Ferruginous sediments in Barberton Mountain Land
A trip back to Archean sedimentary rocks in Barberton, South Africa, reveals a few folds on the roadside…
Friday folds: Continuing contorted Conestoga carbonates
The first Friday of September calls out for a fold. The Burle Business Park in Lancaster, Pennsylvania has an answer – several of them, in fact!
Friday folds: Rifugio Fontana in the Dolomites
TGIF: “Thank Geology It’s Friday!”
Time for a fold or a dozen – let’s travel to the Italian Dolomites to see some kinky crumpled limestones…
Q&A, episode 5
A reader asks: “What is foliation and what makes it so important to the structure of rock?”
Callan answers with a lot of images of beautifully foliated rocks.
Friday folds: Moomaw Reservoir outcrops
Break out your paddle and sunhat. We’re going kayaking on Lake Moomaw, in search of Friday folds…
A suite of deformational features in Lancaster limestones
In the Landisville Quarry, Lancaster, Pennsylvania, there is a quarry that cuts into Cambrian limestones. (The exact identity of these limestones is apparently a matter of some dispute, but that’s not going to stop us!) I visited the quarry in June on a field trip offered through the NAGT’s Eastern Section annual meeting. We witnessed … Read more
Friday fold: Gnarly chert from Spy Rock
The Friday fold is an outcrop of folded chert from the Franciscan mélange in Mendocino County, California. (It should look familiar to anyone who’s ever visited Marin Headlands near San Francisco.)
Chickie’s Rock, Pennsylvania
A virtual field trip to the deformed quartzites and metaconglomerates of Chickie’s Rock and Sam Lewis State Park in Lancaster County, Pennsylvania.
Mafic volcanics atop felsic instrusives: Sonora Pass, California
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!
Deformed conglomerate of Frog Lakes, California
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.