You are browsing the archive for sediment.
5 April 2019
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.
18 March 2019
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!
19 October 2018
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.
12 October 2018
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…
14 September 2018
A trip back to Archean sedimentary rocks in Barberton, South Africa, reveals a few folds on the roadside…
7 September 2018
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!
27 July 2018
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: …
6 July 2018
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 …
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.
1 June 2018
Marli Miller is a senior instructor at the University of Oregon. She is the author of Roadside Geology of Oregon and (with Darrel Cowan) Roadside Geology of Washington. She’s also a very talented geological photographer. She launched a website recently to showcase her work and make it available for instructors: Geology Pics. After chatting with Marli a bit in Flagstaff at the Rocky Mountain / Cordilleran section meetings of GSA …