Callan Bentley Since Tuesday’s big earthquake, we’ve had 5* aftershocks in the same area (and possibly on the same fault). The most recent one popped off last night at 1am. Here’s a plot showing the size of the events (moment magnitude) relative to the passing of time: Note that the quakes that came after “the big one” … Read more
Callan shares a geological analogue that developed in his house yesterday: en echelon tension fractures, common in sheared rocks, appeared on his ceiling due to the Mineral, Virginia earthquake.
Callan describes his experience with the widely-felt east coast earthquake of August 23, and provides an analysis of the fault(s) that may be reponsible.
Fellow geobloggers Brian and Eric have been getting all flutey on us lately, so I figure it’s a good time to show my best photo of flute casts: As the annotated copy suggests, this was taken on the side of the Pennsylvania Turnpike back in March 2008, when four Honors students and I drove up … Read more
As a follow up to last week’s post about halite casts in a hand sample I collected in western Montana’s Belt Supergroup, here’s another example. Unlike those (larger) examples of halite-shaped mud cubes, this sample shows (smaller) examples of the empty space left behind by the dissolved salt crystals: Image is scanned, and the penny … Read more
Setting aside the lack of scale, it really doesn’t get any better than that. Click through to make it huge. This is the Navajo Sandstone, early Jurassic (or late Triassic?) in age. It’s in Zion National Park, Utah. Wind direction was from the right towards the left, as these preserved slip-faces of ancient dunes indicate. … Read more
Callan’s answer to the riddle of the mystery outcrop is revealed. Spoiler: the glacier did it.
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
Here’s one you can click through to make much bigger: That’s a pretty cool outcrop that shows something amazing. Anyone want to take a stab at interpreting it?
I collect a lot of samples when I roam the west on my summer georoadtrips. Yesterday when I got back to my office at NOVA, I unloaded about 200 pounds of rocks from my Prius. These samples are all destined to serve as teaching aides for NOVA and GMU students in lab exercises and/or hallway … Read more
Callan visits the Burgess Shale in British Columbia’s Yoho National Park on a guided tour. This photo-heavy post discusses the depositional setting of this world-famous Cambrian fossil deposit, the landscape along the hike, and (of course) the fossils themselves.
Concentrically-zoned ironstone concretion in sandstone of the Morrison Formation, eastern flank of the Bighorn Mountains / western edge of the Powder River Basin, Wyoming, at the Sheridan College dinosaur fossil quarry, last week. The white stuff is caliche. A quick post to celebrate the fact that as of three hours ago, Lily & I are … Read more
That’s from the side of route 287, somewhere between Fort Collins, Colorado, and the Wyoming border. Though I took this shot >6 weeks ago on my outward-bound trip, today I find myself back in Fort Collins on the eastward leg of my summer road jaunt. And you know what one does in Fort Collins. Happy … Read more
Here’s a cute little feller that we spotted in the Green River Basin of Wyoming last week, whilst checking out the Green River Formation oil shales at the White Mountain escarpment, as well as adjacent Boar’s Tusk volcanic neck and distant Killpecker Dunes. Though sometimes called “horny toads” (I myself am fond of this name), … Read more
Callan embarks on an exhausting climb of a major summit in the Wyoming Bighorn mountains, a peak named in tribute of one of his geological heroes. Come join the trek to the top of Darton Peak!
Here’s one of the first things as you drive north from Chief Mountain in Glacier National Park, and cross the border into Alberta: The mountain in the middle is Crandell Mountain, and it looms to the north above the village of Waterton Lakes, but the lovely folds it displays are best viewed from a more … Read more
Regularly-spaced erosional rills on tailings/road fill at a uranium mining operation in central Wyoming.
To follow up on my March post on the French Thrust, here’s a gigapan of the outcrop. Sun River Canyon, Montana, of course: the Sevier fold-and-thrust belt.
On the way to visit the Bighorn Medicine Wheel, in a road-bottom outcrop of the Bighorn Dolomite (Ordovician), Callan finds a lovely receptaculid fossil (colloquially known as a “sunflower coral,” though it’s not a coral at all).