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4 September 2020
Busy weeks lately; apologies for the minimal bloggery, friends. For this week’s Friday fold, I offer you a view of some of the outdoor decorations at our new house: In the lower basket there is a cut and polished block of Castile Formation rock gypsum + limestone, showing varves that have been folded, apparently by hydration/dehydration volume changes of the gypsum/anyhdrite laminae: This is from the State Line outcrop on …
30 September 2016
Callan’s colleague Joshua Villalobos won the 2016 Biggs Award. He also makes GigaPans of folds, like these talc-bearing rocks of the Allamoore Formation.
27 May 2016
I’ve posted here before about the extraordinary intra-layer folds in the varved evaporite deposits of West Texas’ Permian Basin, but today I can go one better and offer a GIGAmacro look at these lovely folds: Link GIGAmacro by Callan Bentley Enjoy checking these amazing small-scale folds out. They will boggle your mind.
1 December 2015
When snail shells are deposited in a bunch of sediment, they serve as tiny architectural elements, with a “roof” that protects their interiors. Any sediment mixed into the shell’s interior will settle out (more or less horizontally), and then there will be empty space (filled with water, probably) above that. As burial proceeds and diagenesis begins, that pore space may be filled with a mineral deposit, such as sparry calcite. …
2 September 2015
I just finished this excellent memoir by Mary Karr, mostly about her childhood, mostly in east Texas. It’s not explicitly geological but it does feature an oil town economy and a hurricane, as well as some consideration of the Rocky Mountain Front Range in Colorado. I didn’t read it out of any illusions it would be geological, though – I selected it from the library shelf more from a desire …
10 February 2015
Pisolites are large primary concretions that develop in backreef or lagoonal settings such as the Permian Tansil Formation of New Mexico, into which is cut the enormous hole called Carlsbad Caverns.
4 November 2014
Good morning. Here are two images from last March’s “Border to Beltway” field trip to West Texas, on the north flanks of the Cristo Rey laccolith. Specifically, these are Cretaceous strata of the Anapra Sandstone, looking at the bedding plane of the rocks. Cutting across bedding are a series of fractures (joints) that have been highlighted by the oxidation of iron (rusting) along their edges. In the first photo, the …
3 July 2014
What are these Border to Beltway students up to?… Clearly, they are all immersed in their field notebooks, sketching away. This was in March, in west Texas. There must be something worth drawing at this road cut… A clue can be seen on the wall of rock behind them. There, you can find features such as this: And this: And this: Those are outsized clasts of gray limestone in fine-grained …
20 June 2014
The Friday fold visits the Permian basin of west Texas. There, the Castile Formation exhibits gorgeous inter- and intra-bed folding.