Lee Allison, State Geologist of Arizona and exemplar of public outreach via blogging, sent me an e-mail yesterday regarding that awesome coastal Greenland shot by Alistair Knock that I featured as the Friday fold. Lee, like many of you, found the image entrancing and intriguing, and as he explored the unannotated version, he made some … Read more
On Tuesday morning, before the earthquake hit, I answered an e-mail about DC faults. I get unsolicited e-mails all the time (and occasionally phone calls, too). The contact comes from people who have a geological question, find my blog, and figure that I might be willing to answer it for them, or to direct them … Read more
To follow up on my March post on the French Thrust, here’s a gigapan of the outcrop. [gigapan id=”83267″] Sun River Canyon, Montana, of course: the Sevier fold-and-thrust belt.
Here is a trio of concentrically-zoned chert nodules in Mississippian Castle Reef Dolostone, exposed at Sun River Canyon, Montana, just downstream from the roadside outcrop of the French Thrust: If you look closely at the lowermost of the three chert nodules, you’ll see it’s been split and offset by a small fault. Here are close-up … Read more
Dave Lageson of Montana State University and I ran into each on our respective field trips sometime last year outside of the Two Medicine Dinosaur Center in Bynum, Montana, and he told me that I had to go check out the Swift Dam area, a little ways northwest of the town of Depuyer. So, a … Read more
Another thing I saw last week in the Rockfish Conglomerate were several nice examples of “bookshelfing,” which is when a rock or mineral fractures into pieces, and the pieces slide down relative to their neighbors, like a set of encyclopedias slumping outward on a bookshelf. This has the effect of shortening the grain/clast in one … Read more
This Friday, I give you a fold from the shores of the Rockfish River, south of Charlottesville, in Virginia’s Blue Ridge basement complex, and just down the road from the Lawhorne Mill High Strain Zone. The fold distorts (and improves) a felsic dike cutting the darker granite of the basement. You can make this (stitched … Read more
The Friday fold features fine faults from a forgotten font, and a failed foto-finding forage.
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
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. [gigapan id=”78209″] Unfortunately, the auto-stitch deformed my face. I look like Quasimodo. Oh well. As usual, you can see … Read more