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5 October 2011
Two Sisters
All this talk about footprints and tail traces, and I haven’t even shown you any “for sure” dinosaur fossils. Well, let’s remedy that today. We return now to the scene: exposures of the Jurassic Morrison Formation, on the east side of the Bighorn Basin, just north of Shell, Wyoming. I was wandering around, finding things like ripples and lichens and cobbles of chert that had multiple intersecting conchoidal fractures, and …
4 October 2011
Tall tail
Okay, so I was out photographing ripples and admiring lichens, and then I saw this: That’s a rippled slab of sandstone, but with a linear groove that obliquely cross-cuts the ripple marks. Smaller, parallel grooves lie within the main groove. Here’s another look at that same one, spun around and zoomed-in: It looks as if something was dragged through the wet sand at this location, prior to its lithification. Given …
3 October 2011
Lichens on Morrison sandstone
Picking up from Saturday’s post about ripple marks and cross-bedding in Morrison sandstone from north of Shell, Wyoming, let’s scoot away from the purely geological content for a moment, so that we can appreciate some beautiful orange/yellow radial lichens growing on one rippled sandstone slab: You can make that one bigger by clicking on it, or you can look at these close-up lichen portraits below: I love the delicate fading …
1 October 2011
Ripple marks and cross beds in the Morrison Formation
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 Jurassic Morrison Formation. While Butch and his son and his two volunteers went to work …
Callan Bentley is Associate Professor of Geology at Piedmont Virginia Community College in Charlottesville, Virginia. He is a Fellow of the Geological Society of America. For his work on this blog, the National Association of Geoscience Teachers recognized him with the James Shea Award. He has also won the Outstanding Faculty Award from the State Council on Higher Education in Virginia, and the Biggs Award for Excellence in Geoscience Teaching from the Geoscience Education Division of the Geological Society of America. In previous years, Callan served as a contributing editor at EARTH magazine, President of the Geological Society of Washington and President the Geo2YC division of NAGT.