Limestone strata in a variety of orientations, with a nice tilted axial plane. Outcrop is on the east side of the Icefields Parkway, across from one of the many glacier overlooks. Lucy and Alex both wanted to act as sense of scale for this one… Can’t say I blame them.
The Friday fold, delayed by a week from last week’s contest, appears in Yoho National Park, British Columbia, near the “Natural Bridge” over the Kicking Horse River.
The Friday fold is a kink fold in thinly-laminated limestone from the same site as yesterday’s mysterious orange oncoids.
Yesterday, I showed you a scene of geologists (including me) clustered around some (presumably interesting) outcrop. I asked what you thought we might be looking at. Howard Allen, a denizen of this part of the globe, immediately identified the scene as that of the downstream end of the Athabasca Glacier. Several people guessed that we … Read more
Here’s the view riding up (or down) Sulphur Mountain, Banff, on the gondola: As you can probably tell from the cable lines’ misalignment, this was a composite (stitched) photo. Mt. Rundle is in the background. If you turn to the left, you can see Tunnel Mountain, south of the town of Banff: Tunnel Mountain is … Read more
One of Callan’s former students leads a field trip to examine the western edge of the Blue Ridge geologic province, attempting to answer the question of whether the Blue Ridge / Valley & Ridge contact is indeed the trace of a thrust fault. Breccias and S-C fabrics tell part of the story…
One more structure from the Castner Marble. This one is clearly tectonically-induced: Top to the left! (East over west)
The Castner Marble is an extraordinary Mesoproterozoic limestone (later re-crystallized and metamorphosed) that exhibits some primary structures (both explicit and ambiguous) and some secondary (tectonic) overprints. It’s exposed in the Franklin Mountains of west Texas.
Hand sample of folded limestone strata in West Virginia (presumably Devonian in age). Note the rip-up clasts and large grain size at the base of the sample (to the right in the photo). Note the fine-grained, thin-bedded shale laminations towards the top (left) of the sample, too. Together, they tell a story of decreasing energy … Read more
Yesterday I flew from DC to Reno, Nevada in the company of 11 students, and then we rented vehicles and drove south on Route 395, one of the greatest roads in America, to Bishop, California, where we area based for the next 3 days. We’re doing a regional field geology course examining the extraordinary rocks, … Read more
Riding a cable-car up the side of the Franklin Mountains, Callan checks out the local stratigraphy and structure (and igneous intrusions). Join him on an insightful cruise up several thousand feet and through a billion years of geologic time.
From the road that keeps on giving: new New Route 55, in West Virginia, west of Moorefield.
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.
After our safari, Lily and I were taken up onto the Great Escarpment in northern South Africa. The escarpment is supported by sedimentary strata of the Transvaal Supergroup that overlie the Archean basement rock of the Kaapvaal Craton. The Transvaal strata are Paleoproterozoic in age, somewhere between 2.5 and 2.0 billion years old. They are … Read more
With my new “macrogigapan” rig from Four Chambers Studio, I produced these images last week as part of my Mid-Atlantic Geo-Image Collection project (M.A.G.I.C.). … Dive in! Porphyritic andesite from the Beartooth Plateau, Montana: Foliated limestone slate, location unknown: Clicking on the word “GigaPan” in the lower right corner will take you to a fuller-screen … Read more
With my new “macrogigapan” rig from Four Chambers Studio, I produced this image last week before I left on vacation: That sample measures 18.5 cm long, and is about 4.9 cm wide. Pretty good resolution, eh?
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
Elizabeth Eide of the National Academies shared this image with me a year or two ago, when she gave a talk on Norwegian geology for the Geological Society of Washington. Those are some bookshelfed gneiss layers sandwiched between upper-left and lower-right carbonates. The “bookshelfing” refers to the numerous parallel brittle fractures along which the gneiss … Read more
My man Walcott contributed a lot of images to the USGS stockpile during his travels. Today, I’ll feature one from Bishop, California, from 1894: Got it from here. Rock hammer on the left for scale. The caption reads: Plicated layers of thin bedded chert in limestone etched by erosion, Lower Cambrian (?). Hill two miles … Read more