Friday fold: shale and sandstone from West Texas
No time for more details than that – sorry! Happy Friday and a restful weekend to all!
folds
GigaPan suite from the South Page Valley Martinsburg Outcrop
Are you into structure? Sedimentology? Stratigraphy? Well, I’ve got some good news for you – I’ve imaged several key outcrops on the newly-discovered (to me) roadcut on South Page Valley Road, showcasing the middle Martinsburg Formation turbidites (and their Alleghanian structural overprint). link link link link link link See if you can find: an anticline … Read more
Friday fold: “V”
The Friday fold photo was taken this morning on a GigaPanning expedition, and shows a small syncline within turbidite strata of the Martinsburg Formation, Page Valley, Virginia.
Friday fold: the case of the strangely stout stylolites
Today, we return to my field trip from last week, for a look at an odd outcrop of the Ordovician-aged Edinburg Formation: Note the car key with green lanyard, to provide a sense of scale. It’s folded, as the yellow bedding traces show in this annotated version: But what really caught my eye about this … Read more
A closer look at the recumbent anticline from last Friday
Last week, the Friday fold was presented in GigaPan format only, which led to a concerned reader lamenting that he couldn’t see it on his mobile device. (GigaPans are Flash-based images; they don’t work on Apple devices in the standard GigaPan format, though there is a perfectly suitable workaround with two extra clicks.) So, for … Read more
Friday fold: a recumbent anticline in an abandoned quarry
Yesterday, I spent a pleasant day in the field with John Singleton, the new structural geology professor at George Mason University. I was showing John a couple of sites I’ve used as field trip locations for the GMU structural geology class, and John was showing a couple of new sites to me – places he … Read more
Friday fold: Fault propagation fold from Cristo Rey
The Friday fold comes from the Texas – New Mexico – Chihuahua triple point, on the flanks of Cristo Rey mountain.
Friday fold: An odd duck
A USGS colleague shows Callan a bizarre fold outcrop in the Conococheague limestone of the Boyce quadrangle, Virginia.
Unconformity seen in the field yesterday
Callan and two colleagues find a “textbook” unconformity on a field trip in Virginia’s westernmost Blue Ridge.
Friday fold: Martin’s metamorphics
A guest “Friday fold” from South Africa: folded gneisses, flavored with other treats of a geological nature.
Crazy veins
Callan & his students visit an outcrop on the Icefields Parkway in Alberta, showing a variety of white veins cutting dark rock.
Friday fold: clear evidence of the work of the Intelligent Folder
Yesterday’s post showcasing my conversational critique of Intelligent Design got a lot of attention, including tweet love from @NCSE and @BadAstronomer, and a blog post at Pharyngula. So, at the risk of overkill, I decided to have a little fun with the Friday fold… Check out this fold that I found in float of Purcell … Read more
Some ductile deformation in Mosaic Canyon
Following the “monster” that was the Friday fold two weeks ago, here are some more folds in the Noonday Dolostone (“Dolomite”) in Mosaic Canyon, Death Valley, California: Zooming in on this isoclinal fold: Bedding traces annotated, highlighting the “similar” style of folding (hinge thickened; limbs thinned): A very different style of folding, observed a few … Read more
Friday fold: LIDAR view of the Weverton Formation along the Blue Ridge front
Dan Doctor of the US Geological Survey contributed this week’s Friday fold. It’s a lovely view of the asymmetric folds in the Cambrian-aged Weverton Formation (part of the Chilhowee Group, a Sauk-Sea passive margin transgressive sequence), exposed on the western flank of the western limb of the Blue Ridge Anticlinorium. It’s a LIDAR image, and … Read more
Friday fold: Mosaic Canyon Monster
While out in Death Valley with my Field Studies students last March, we encountered an extraordinary fold in Mosaic Canyon. Check this thing out: The rock is the Noonday Dolostone (“Noonday Dolomite” in mineralogically biased argot). It may be hard to make out what’s what there… So let me assist with a little annotation, tracing … Read more
Friday fold: Gansbaai
A small mountain inland of Gansbaai, South Africa (where one goes to cage-dive with great white sharks) shows some of the folding characteristic of the Cape Fold Belt. Let’s zoom in… A few bedding traces annotated, to ease your armchair fold-viewing experience. I think this is my final photo from South Africa… Wow. Only took … Read more
Fold mystery – UPDATED
What can you tell me about this new fold sample I recently acquired? Width of sample is 12.5 cm. The face you’re looking at was cut but not polished. Here’s a close up: With layering annotated, to highlight the disharmonic nature of these folds: Anyone have any guesses what’s going on here? ——————– UPDATE —————— … Read more
Friday fold: “Chasing Ice”
Callan watches the new documentary “Chasing Ice” about James Balog’s Extreme Ice Survey project, and spots a lovely Z-fold during the largest glacial calving event ever recorded.
Friday fold: Hoerikwaggo Trail 5
We wrap up our week-long odyssey along South Africa’s Hoerikwaggo Trail with a look at something we look at every Friday: folds! In this case, we’ll be examining folds in the bedding layers of the Table Mountain Sandstone.
Friday fold: Up on Opequon Creek
I got a call last month from Rebekah Wiedower, a landowner up in Frederick & Clarke counties (her family’s property includes pieces of both), inviting me to come up and look at some anticlines and synclines that Dan Doctor (USGS) had identified on the bank of Opequon Creek. I was glad to do it, though … Read more