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
Visiting Butch Dooley and crew on a dinosaur dig in the Jurassic Morrison Formation on Wednesday morning, I did a lot of wandering around the area, dubbed the Two Sisters site. I noticed something in the sandstone at the top of one hillock, and thought it looked like a sauropod footprint: (The depression is filled … Read more
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
While exploring the Rock Creek Cemetery last week, I noticed a couple of other interesting graves. This one, made of limestone, shows nice “reverse” cross-bedding: Here; I dialed up the contrast a bit to highlight these cool primary structures: It’s “reverse” because the tilting direction of the cross-beds switches from left (at the bottom) to … Read more
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.
My friend JT, who got her MS in geology at the University of Maryland when I did, is now at the Colorado School of Mines working on her PhD in Environmental Science and Engineering. A water main broke outside her house this morning, and I’m pleased that her first thought was to photo-document the resulting … Read more