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You are browsing the archive for sediment Archives - Mountain Beltway.

11 July 2019

A submarine slump complex at Sandy Cove, Newfoundland

Traveling in Newfoundland, Callan visits a seaside outcrop showing a Proterozoic submarine slump complex, overprinted by tectonic cleavage and weathered by the sea.

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5 April 2019

Friday fold: Angel Island “I”

The Friday fold is on the north shore of Angel Island, San Francisco Bay, showing blueschist-facies high-contrast metalliferous cherts with folds on many scales.

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18 March 2019

New discoveries in the Martinsburg Formation

A virtual field trip to examine some deepwater clastic sediments shed off the first phase of Appalachian mountain building, and deformed in the third phase. It’s a lovely day for a field trip to the late Ordovician!

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19 October 2018

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.

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12 October 2018

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…

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14 September 2018

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…

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7 September 2018

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!

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27 July 2018

Friday fold: new folds from the Empire Formation, Glacier National Park

Hiking Siyeh Pass in Glacier in Glacier National Park on Tuesday with my Montana State University field course, we spotted a few new folds in the Empire Formation (a transitional unit between Helena Formation and Grinnell Formation). Here is one of the students serving as a sense of scale, with interesting features on either side of him: On the left, there are small scale folds in a regular little train: …

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6 July 2018

Friday fold: twisted turbidites at Usal Beach

Last week, I spent two perfect days camping with family at Usal Beach, in Mendocino County, California. Along the beachside cliffs there, I spotted plenty of lovely turbidites: graywacke and shale and a little bit of conglomerate that had been scraped off the subducted Farrallon Plate to help contribute to the bulk of the Franciscan complex. That accretionary process imparted some stresses on these deep-sea deposits, and in many places …

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23 June 2018

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.

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