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4 September 2020
Friday fold: Home décor
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 …
11 February 2019
When Bugs Were Big, Plants Were Strange, and Tetrapods Stalked the Earth: A Cartoon Prehistory of Life Before Dinosaurs, by Hannah Bonner
It has been a while since I’ve reviewed any kids’ books here, but this one was so good that I just have to tell you about it. My son is now 6 and a half years old, and he’s interested in all sorts of natural history topics. Given that I’m a geologist, he’s probably more Earth-science-focused than the average kid, but my wife is a biologist, so he’s got plenty …
26 January 2018
Friday fold: eastern Andes
This image graces the cover of the new report, Challenges and opportunities for research in tectonics: Understanding deformation and the processes that link Earth systems, from geologic time to human time. A community vision document submitted to the U.S. National Science Foundation: Make it bigger by clicking it The photo is of a landscape in the Eastern Cordillera of the Andes, southern Peru, showing folded Permian carbonates cut by a …
22 December 2016
Dikes at Bunnahabhain
Yesterday I blogged the stromatolites to be seen in northeastern Islay, south along the shore from the distillery at Bunnahabhain. The sharp-eyed among you may have noticed that in this GigaPan, there’s more going on than merely Neoproterozoic carbonates: [gigapan id=”189616″] Link 1.46 Gpx GigaPan by Callan Bentley There’s also a prominent dolerite dike, weathering out recessively. A photo, centered on the GigaPanned dike: This is but one of several …
4 July 2016
Virtual field trip to Kinkell Braes, Scotland
Walking along the shore east from St. Andrews, Scotland, along the seaside sandstones of Kinkell Braes, you encounter several extraordinary examples of geology. It’s a great place for the next stop on our Grand Tour of the geology of the British Isles. Here’s the scene: The first stop is a giant eurypterid trackway, potentially the largest invertebrate trackway in the world (Whyte, 2005), on the underside of an overhanging sandstone …
1 December 2015
Which way’s up? Check cavity fills.
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. …
10 February 2015
Pisolites in the Tansil Formation, Carlsbad Caverns, New Mexico
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.
7 May 2013
Brallier Formation 2: tectonic structures
Yesterday we examined primary sedimentary structures (including trace fossils) at an outcrop of Devonian-aged Brallier Formation turbidites between Deerfield and West Augusta, Virginia. Today, we’ll zoom in on the tectonic structures at the site: folds, faults, and joints. Remember, you don’t have to take my word for it. You can explore it for yourself in this M.A.G.I.C. GigaPan: [gigapan id=”128612″] link One thing that’s kind of cool about that GigaPan …
27 June 2011
Goose Egg / Tensleep contact
West of Shell, Wyoming, on route 14, there is a lovely exposure showing the tilted stratigraphic contact between the lower Tensleep Formation (purple; Pennsylvanian period) underneath Goose Egg Formation (orange/tan; Permian to Triassic in age). The contact dips to the west because it has been deformed during Laramide mountain-building (uplift of the Bighorn block, and downdropping of the Bighorn basin). Here’s a gigapan to show the contact: [gigapan id=”80391″]
