Had this brainstorm a few weeks back (or maybe months?). Been meaning to blog it up, but hadn’t gotten the chance to flesh it out. The geologic map of the Commonwealth comes from Chuck Bailey of William & Mary, who gave me permission to use it for this project. Anyhow – do you think there … Read more
Why are these people smiling? photo by Yvette Kuiper Because they are structural geologists, and they are psyched to be at an extraordinary outcrop: This is a famous pavement outcrop of polyphase-folded banded iron formation (BIF) near Soudan, Minnesota. I went there last fall before the annual meeting of the Geological Society of America, on … Read more
This beastie lives in an old quarry in West Virginia, along old Route 55. And from a slightly different perspective… This fold is in Devonian limestones of the Helderberg Group, kinked up probably during the Alleghanian Orogeny (the assembly of Pangea) in the late Paleozoic.
Nice straight-limbed syncline in the Helderberg Group of West Virginia (Devonian limestones, mainly): Alan Pitts shot a sweet GigaPan of this outcrop which you can explore here, or you can just look at this zoomed-in detail: Aaron Barth is down there in the lower right corner for scale.
These are turbidites of the Malmsbury Group in South Africa, on the east shore of False Bay. A couple of nice little folds running sub-vertically through the package… Happy Friday!
Callan and his wife journey to Africa’s southernmost point, and find a geological mystery there.
Last weekend, my wife and I joined friends for a weekend of cross-country skiing in the wonderful Canaan Valley of West Virginia. On the way back, between the towns of Burlington and Romney, West Virginia, I saw this folded shale on the north side of Route 50: You can click on that panorama to make … Read more
In the White Mountains of eastern California, just west of the Deep Springs Basin (site of my coldest camping experience ever, followed by a memorable morning walk in the playa and discovery of a bat mummified by salt), there lies a classic field mapping location, the Poleta folds. Here’s what it looks like from Google … Read more
Callan reviews the geology of the superlatively auriferous Witwatersrand Supergroup of South Africa, and then zooms in on a distinctive marker bed near the base of the sequence. The deformation in this particular banded iron formation (BIF) is an aesthetic wonder, as this suite of images reveal. The layer outcrops in the heart of urban Johannesburg.
While I was away in South Africa, both Brian Romans of Clastic Detritus and Evelyn Mervine of Georneys posted pictures of folds in quartzite of the Cape Fold Belt in southern South Africa. Well, I’m not going to be left out. Here’s a belated Friday fold for December 23, showing a bunch of sweet folds … Read more
Another Friday fold from the pre-GSA Superior Craton field trip: Happy Friday. I’m setting this to auto-post on the day that my wife and I arrive in Johannesburg to start our honeymoon. I hope everyone’s doing well in my absence.
The Friday fold is found on a newly-opened section of road in West Virginia. Join Callan in checking out some synclines and associated faults in the Devonian-aged Brallier Formation.
Today the Friday fold comes with copious bonus structures. It’s the first stop we hit on Day 3 of the pre-GSA Minneapolis field trip to examine the structural geology of the subprovince boundaries within the Superior Craton. This particular site showed granitoid dikes that had been deformed during dextral transpression into a variety of structures … Read more
Sorry to be late with this – I think that’s the first time I’ve forgotten to post a Friday fold. Blame it on the tryptophan.
Okay – in spite of numerous distractions (see every other post so far this week), it’s time to return to the pre-GSA Minneapolis structural geology field trip. Our final stop of the second day in the field was a series of folded up mafic metavolcanics. I’ve got some photographs of them. These mafic volcanics were … Read more
At last weekend’s gala banquet to celebrate the 50th anniversary of the William & Mary geology department, I was tickled to see that the centerpiece for each table was a rock of some sort. I spotted Gore Mountain Amphibolite, Baker Mountain Kyanite, brachiopod fossils in limestone, a fossil whale vertebra, a chunk of Aquia Creek … Read more
Today’s fold is an anticline and its neighboring syncline, both exposed along a newly-opened stretch of New Route 55, west of Moorefield, West Virginia. The new Route 55 is a classic porkbarrel boondoggle courtesy of the late Senator Robert Byrd, but doggone if it didn’t open up some lovely new roadcuts. Here’s a stitched image … Read more
This summer, a week or two after our wedding, my wife and I found ourselves in the Canadian Rockies for a pre-honeymoon. Part of our time was spent on a backpacking trip to Floe Lake in Kootenay National Park, British Columbia. On our hike in, we passed this outcrop of Chancellor Slate, a Cambrian aged … Read more
Why are these geologists all over these rocks? Because, gentle readers, these are some seriously cool rocks. The geologists are all participants on a pre-GSA-annual-meeting field trip to the Superior Craton, a chunk of ancient crust at the “nucleus” of the North American continent. The rocks are syn-tectonic volcaniclastic conglomerates of the Seine Group. They … Read more
Wednesday, Alton Dooley put up a post about his visit to Van Hise Rock in Wisconsin. He included this photo of the famous rock with its upright (pretty much vertical) layers: Go read his description of the lithology for more detail, but essentially what you see here is an Oreo-like sandwich: pink quartzite (meta-sandstone) on … Read more