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). [gigapan id=”126510″] link [gigapan id=”126514″] link [gigapan id=”126509″] link [gigapan id=”126483″] link [gigapan … Read more
During Alleghanian deformation (late Paleozoic), the Cub Sandstone we looked at yesterday was tilted to near vertical at Catherine Furnace. The shale layers developed cleavage at this time, and there was evidently some flexural slip between sandstone layers, to judge from these fine slickensides: Students: Can you deduce the sense of motion from the orientation … Read more
Today, two GigaPans shot of the uppermost Martinsburg Formation, informally known as the “Cub Sandstone” since it crops out along Cub Run in the southern part of the Massanutten range. 10 or 15 meters upsection (west) of these two outcrops is the base of the Silurian-aged Massanutten Sandstone, the ridge-forming unit. Lower in the section: … Read more
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
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
Yesterday, I took five new GigaPans at Thoroughfare Gap, a water gap where Broad Run cuts through Bull Run Mountain, the eastern limb of the Blue Ridge Anticlinorium at my latitude. The rocks here are the Cambrian-aged Chilhowee Group, with bedding tilted moderately to the east during Alleghanian mountain-building in the late Paleozoic. To the … Read more
The Friday fold comes from the Texas – New Mexico – Chihuahua triple point, on the flanks of Cristo Rey mountain.
A USGS colleague shows Callan a bizarre fold outcrop in the Conococheague limestone of the Boyce quadrangle, Virginia.
A guest “Friday fold” from South Africa: folded gneisses, flavored with other treats of a geological nature.
Whoa – look at all that GREEN. You can tell this Virginia picture wasn’t taken recently. In fact, it’s another image from the field review I participated in for the Elkton East quadrangle back in May of last year. Somehow I start blogging these things, but run out of steam (or really more accurately: I … Read more