You are browsing the archive for national parks.
14 December 2018
A guest Friday fold brings us to a position in the sky somewhere over eastern Death Valley National Park. Join us in contemplating the Titus Canyon Anticline.
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 …
3 November 2017
This Friday, let’s return to Glacier National Park. Here are some folds in Helena Formation limestone: Can’t see them? Fair enough – the point of maximum inflection appears to be hidden behind a snow-filled gully: But in addition to that big fold, there are several kink bands in there, too. Let’s zoom in: Here they are: Zooming in further, on the right-most of these kink bands: …And here, with the …
20 October 2017
Over the summer, I treated you to a great big kink fold in the sedimentary rocks of Glacier National Park. Here’s another set: Did you see both of them in that first picture? – one bigger down below, one smaller up above. Both kink bands dip to the left. Let’s zoom in on the upper one: There’s more where this came from – stay tuned for more…. and in the …
9 August 2017
A showcase of five new 3D digital models of awesome rock samples and outcrops, produced using Agisoft Photoscan.
28 July 2017
It’s Friday! How about we celebrate with a beautiful kink fold from a gorgeous national park?
5 May 2017
It’s Friday, the end of the workweek, but also the beginning of the celebration of folded rocks. Examine a particularly sinuous example from the buckled Cambrian limestones of Canada’s Kootenay National Park.
15 April 2017
My son and I hiked Compton Peak in Shenandoah National Park this morning, and saw these two lovely examples of xenoliths. The example above is small, but it shows clearly the difference between the coarse, felsic basement rock (Mesoproterozoic granitoid, comprising the xenolith) and the surrounding fine-grained dark green metabasalt of the Catoctin Formation (Neoproterozoic). Here’s another, bigger example: These two Blue Ridge examples both illustrate the principle of relative …
29 October 2016
In Shenandoah National Park, astride Virginia’s Blue Ridge, feeder dikes of Catoctin Formation (meta-)basalt cut across the Grenvillian-aged granitoid basement. Due to their mafic composition and columnar jointing, these feeder dikes generally weather more rapidly than their host rocks. I led a field trip in the park on Thursday for my son’s school, and my student Marissa was there the weekend prior, checking out the autumn leaves and geology with …