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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 …


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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 …


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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 …


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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 …


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