This is a boulder of Cambrian-aged Flathead Sandstone, the unit overlying the Great Unconformity exposed in Wind River Canyon, Wyoming. Click to make it 5000 pixels wide. Swiss Army knife for scale. It shows a lovely example of multiple upside-down cross-beds. It also shows a heavy layer of caliche on what is (now) the upper … Read more
This past summer, the day after my examination of basement complex along the Colorado/Wyoming border, I drove north to Greybull, and then with Virginia Museum of Natural History paleontologist Butch Dooley to a dinosaur dig site north of Shell, Wyoming. There, in the Bighorn Basin west of the Bighorn Mountains, are dinosaur-bearing exposures of the … Read more
Giant City State Park is a patch of protected forest south of Carbondale, Illinois, where there are some pretty cool exposures of Pennsylvanian-aged Makanda Sandstone. Here’s a typical look at one: Notice the deep chasm on the right. This leads, maze-like, to other flat-bottomed and vertically-walled canyons: The orthogonal joint sets produces some nice tall, … Read more
Hurricane Irene passed this way two weeks ago, and dumped a lot of rain on the mid-Atlantic region and the northeast. As a result, runoff increased, rivers swelled, and sediment was mobilized. Some of that sediment was suspended and transported downstream. On Tuesday, I got this e-mail from my colleague Ken Rasmussen, who took students … Read more
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.
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.
Regularly-spaced erosional rills on tailings/road fill at a uranium mining operation in central Wyoming.
On my hike to the Burgess Shale earlier this week, we encountered some great geology as well as paleontology. For instance, consider this rather epic alluvial fan, spilling out of the Presidential Range to the northwest of Fossil Ridge and Mount Burgess, and rapidly filling the Emerald Lake basin. Here’s a Google Map link to … Read more
The other day, driving south through Yellowstone on our way to the Tetons, I stopped to give my students the obligatory look over Yellowstone Lake’s West Thumb, looking east towards the snowcapped Absaroka Range in the distance. But in addition to a lovely view and a few birds, we found something really cool… Those are … 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
Callan presents a gazillion photos from a field trip to examine the Rockfish Conglomerate, a potential Snowball Earth glacial outwash facies from the Neoproterozoic of the Virginia Blue Ridge province.
I just drew up a little checklist for the different formations my Rockies students will be seeing next starting next week out in Montana: The original black and white images (two columns on two pages) come from Self-Guided Field Trips Near Bozeman (1982), by Stephan G. Custer, Donald L. Smith, Molly Walker, and 1982’s crop … Read more
While my focus was more on bugs and plants than geology this time around, I did hike a new trail at Dolly Sods this past weekend, and on that trail I found several nice boulders of conglomerate. These stood out as being much coarser than the pervasive quartz sandstone of the Pennsylvanian-aged Conemaugh Group which … 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. Unfortunately, the auto-stitch deformed my face. I look like Quasimodo. Oh well. As usual, you can see it full … Read more
Another day, another geology LOLcat challenged issued by a geoblogger… Okay, I’ll bite: Other geology LOLcats have been found curling up all over the geoblogosphere in the past 24 hours: Outside the Interzone Georneys
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.