You are browsing the archive for boudinage.
26 October 2018
It’s been a very Billy-Goaty week for me. Three times since Sunday afternoon, I’ve taken people to the Billy Goat Trail’s “A” loop in C&O Canal National Historical Park. On Tuesday and Thursday, it was my NOVA Physical Geology students. On Sunday, though, it was just my son and me. Good news! He helped me discover a new fold by exploring some new rock outcrops and climbing on them. He …
16 August 2018
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 multiple varieties of deformation there. First off, there was straight-up brittle extension, resulting in bedding-perpendicular …
27 March 2017
Explore a dozen photos highlighting the structural geology of an outcrop of limestone and shale near Lexington, Virginia. Cleavage refraction, overturned beds, boudinage, folds, and even a small fossil – we’ve got something for everyone. Bring the whole family!
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 …
22 July 2016
When in Shetland, one of my first stops was the museum in Scalloway, and one of the ancillary benefits of visiting there is the castle next door: Scalloway Castle includes building stones derived from the local limestone – a Neoproterozoic unit that has recently been chemostratigraphically correlated with Snowball Earth cap carbonates elsewhere in the world. But that need not concern us today. Today we are here for the folds! …
11 July 2016
I’m in the North-West Highlands of Scotland, enjoying spectacular geology and less-than-spectacular weather. I’ve been fairly productive on the GigaPan front, regardless, nipping outdoors when the weather permits to shoot outcrops and landscapes. One set I’m particularly pleased with is this suite of four images. They show the Archean-aged Lewisian gneiss, the oldest rock unit in the North-West Highlands, as exposed on a beachside outcrop east of Durness, Sutherland. The …
10 June 2016
There are some structural goodies here at the confluence of the Rapid River and the Salmon River in west-central Idaho. I visited these outcrops three weeks ago on a field trip after the Rocky Mountain section meeting of GSA. The rocks are the Lightning Creek Schist, a schist that’s part of the Wallowa Terrane, an accreted chunk of crust that docked with western North America during the Mesozoic. Here is …
4 March 2016
It’s Friday, so in search of an appropriate fold, Joe Kopera leads us to the top of New Hampshire’s Mt. Monadnock. Bonus: boudinage!
12 December 2014
The Friday fold returns to Canada, looking at Neoproterozoic slate and quartzite at the southern terminus of the Icefields Parkway. Bonus features include ripple marks, graded beds, cross-bedding, cleavage, and boudinage.
16 October 2014
While on my blueschist quest, I noticed this boudin train exposed in the trail. I’m not sure what exactly is being boudinaged here – only that it is lighter in color than the schist that surrounds it, as well as finer grained and less foliated (more massive). A tabular mass of fault gouge perhaps?