You are browsing the archive for Friday Fold Archives - Mountain Beltway.
21 October 2016
Sometimes you find big ideas in small places. Here, a South African chert boulder mimics in miniature fold and thrust belts the world over.
7 October 2016
Remember St. Ninian’s Isle? It is connected to Mainland Shetland by a tombolo. But it has rocks there, too. Here are some outcrops on the beach: If you visit these schisty fins, you’ll find they are populated by a cavalcade of small folds. Some of the folds are crisp things known as kink bands: Annotated version: And finally, as a lagniappe, here’s a bit of boudinage. This quartz vein has …
30 September 2016
Callan’s colleague Joshua Villalobos won the 2016 Biggs Award. He also makes GigaPans of folds, like these talc-bearing rocks of the Allamoore Formation.
23 September 2016
Can a Friday fold be a work of art as well as a source of geologic insight? The answer can be found as you enter Shetland’s Northmavine region.
16 September 2016
The Friday fold is a guest submission from Bill Burton, who took the photo of these lovely ptygmatic folds in migmatite in a national park on the 100th anniversary of the founding of the Park Service.
9 September 2016
A virtual field trip to the Walls Boundary Fault in Shetland reveals an embarrassment of Friday fold riches.
2 September 2016
A quick Friday fold – Ulundi Formation, basal Fig Tree Group of the Barberton Greenstone Belt, exposed in a creekbed etched into the trace of the Sheba Fault. This is one of the outcrops I visited one week ago today as part of the pre-IGC field trip to the Barberton. The rocks are iron-rich cherts and pelites that have enjoyed some serious strain, presumably due to movement along the Sheba …
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!
5 August 2016
Martin Schmidt again contributes a fold – this time from his summer trip to South Africa: Pretty great! This is part of the Cape Fold Belt. Perhaps some of you will drive by it when you go to the International Geological Congress in South Africa later this month! You can view the site in the context of Google Street view here. Thanks for sharing, Martin.
29 July 2016
A quick Friday fold here from the North-West Highlands of Scotland: These are Lewisian gneisses exposed on a headland northwest of the little outpost of Tarbet (where the Handa Island ferry departs from). I was out there in search of shear zones, but I found plenty of nice folds, too. There are two main folds in the image – a synform in the foreground (yellow), and an antiform in the …