Lawhorne Mill High Strain Zone
Callan attends a field trip in the Blue Ridge of Virginia, looking first at a Paleozoic shear zone that disrupts (and improves) Mesoproterozoic basement complex rocks.
virginia
Portrait of a cricket
Spied this lovely cricket while hiking the White Oak Canyon Trail in Shenandoah National Park yesterday: I realize there’s been a pretty high bugs : rocks ratio on Mountain Beltway of late; I’m just in summer mode, I reckon. And Virginia’s arthropod profligacy keeps bringing me into contact with these extraordinary segmented denizens of the … Read more
The grave of John Wesley Powell
Callan visits the grave of John Wesley Powell, second director of the USGS and explorer of the Grand Canyon, on an afternoon in Arlington National Cemetery.
Friday fold(s): the Outdoor Lab
Today’s Friday fold takes me back 25 years, to when I visited the Outdoor Lab with my science class in Arlington County Public Schools. I revisited this exemplary outdoor education facility on Tuesday, at the invitation of its director, Neil Heinekamp. Neil wanted a geology “expert” to take a look at their rocks, and I … Read more
Tumbling Run: New Market/Lincolnshire contact
Here’s a gigapan I shot yesterday, looking north at the contact between the New Market and Lincolnshire Formations at the classic “Tumbling Run” outcrop south of Strasburg, Virginia: See if you can find the E. coli plush toy I included, or the cm-scale pencil! As usual, you can see it full screen, by clicking on … Read more
The view from Signal Knob
Here’s a gigapan I shot last Saturday, looking north from Signal Knob, Virginia: As usual, you can see it full screen, by clicking on the word “Gigapan” in the lower right.
Fault in Massanutten Sandstone
Here’s a gigapan I shot last yesterday, looking west from “Blue Hole” towards a cliff of Massanutten Formation sandstone, south of Waterlick, Virginia. A prominent fault zone can be seen in the center of the image. Unfortunately, the auto-stitch deformed my face. I look like Quasimodo. Oh well. As usual, you can see it full … Read more
A tidy little quartz crystal
A doubly-terminated quartz crystal (or “Herkimer diamond”) is found on a hike in the Silurian sandstones of Virginia’s Valley & Ridge province.
New hallway display: geologic provinces of northern Virginia
Callan shows off a new hallway display in his building at Northern Virginia Community College, showcasing the numerous geologic provinces of northern Virginia (as well as adjacent mid-Atlantic states).
Some cool rocks from DGMR’s rock garden
A brief tour of some cool rocks, shown in close-up, from the rock garden at the Commonwealth of Virginia’s Department of Geology and Mineral Resources in Charlottesville, Virginia, presented as a follow-on to the gigapan of the garden shown a month ago. The post features close-ups of plumose structure in slate, epidote slickensides, and graded bedding in ancient rhythmites.
Friday fold(s): More kinky phyllite, but this time from the field
Last week, the Friday fold featured a kinked phyllite of unknown provenance that is currently resident in David King Hall 2074 on the campus of George Mason University. However, on Tuesday of last week, I found another kinked phyllite, this one out in the real world, at Thoroughfare Gap, in the Harpers Formation of the … Read more
Deformational fabrics in the Weverton Formation
My student Troy was working on the geologic history of the Thoroughfare Gap regions for his Honors project this semester, and we went out there last week to check out some stuff. One thing I was struck by was how much more deformed these rocks were than I had expected. This was particularly evident in … Read more
Pseudoscorpion sighting at Thoroughfare Gap
On the original version of this blog, I showed off a couple of pseudoscorpions that I found under a rock in Montana. On Tuesday, poking around at pollen-ific Thoroughfare Gap with my Honors student Troy, I found another one. Looked like the same thing. See for yourself. I shot a bunch of macro shots with … Read more
My structural superpower
If I had a structural superpower, it would be to shoot en echelon tension gash arrays from my fingertips: Photo by Sharon Ruggeiri
Explore the DGMR rock garden
I shot this gigapan (900 images) last Thursday during the lunch break of the annual “Geology of Virginia” symposium hosted by the Commonwealth of Virginia’s Department of Geology and Mineral Resources. It shows the rock garden outside the DGMR’s offices in Charlottesville, a place where they have collected charismatic megasamples from across the state’s five … Read more
Old Rag gigapans
Lily and I took a hike yesterday over Old Rag Mountain, a popular destination in Shenandoah National Park. I took the opportunity to shoot a few gigapan images of the scene. If you click on the word “Gigapan” in the lower right of any of these images, it will take you to gigapan.org’s full page … Read more
The Big Bentonite just got smaller
The Shenandoah Valley of western Virginia records the switch in late Ordovician time from passive margin sedimentation associated with the Sauk and Tippecanoe epeiric seas, to active margin sedimentation associated with the onset of the Taconian Orogeny to the east. Higher up in the stack, a similar pattern is seen: a return to passive margin … Read more
Friday fold: OSF migmatite
Migmatite schist sample from Orange Springs Farm, near Unionville, Virginia, with cm-demarcated pencil for scale. Sample was cut and polished. Here’s what the untreated sample looks like: [youtube=http://www.youtube.com/watch?v=XDDcLVp_4Ss] Happy Friday. Enjoy your weekend. I’m off to the Northeastern / North-Central joint section meeting of the Geological Society of America today. We’ll see if my time … Read more
Buzzard Rock
Took a hike this morning with my bride-to-be, out to Buzzard Rock on the northeastern corner of Massanutten Mountain. There, we observed numerous boulders of Massanutten Sandstone float, many bearing charismatic cross-beds. Here’s one more slab of float, presumably weathered out along the main bed, showing gorgeous internal cross-stratification: A closer look at the left … Read more
Friday fold: Buckled vein in the Catoctin
Another fold seen in the Catoctin Formation, where last week we encountered a very different style of folding — chevrons overprinting Catoctin foliation. Here, we instead have a light colored vein that appears to have been buckled into a semi-ptygmatic form. The trace of the foliation in the Catoctin is discernible, too. Enjoy your Friday!