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15 April 2022

Friday fold: Cretaceous Canada

A guest contribution for the Friday fold, from reader Christian Gronau: Christian reports that this is located on the North side of Hwy.11, 20 miles east of Saskatchewan River Crossing, Alberta. Eastern foothills of the Canadian Rocky Mountains. Faulting and folding in Early Cretaceous Luscar Group sediments.  Typical repeating sequence of sandstone, siltstone and coal. Thanks for pitching in, Christian! Happy Friday to all!


15 May 2020

Friday fold: Argentinian turbidites

Zoltán Sylvester brings us this Friday’s fold: And there’s more where that came from: These are deepwater strata of the Lower Cretaceous Rio Mayer Formation, exposed near Lago Argentino, Argentina, south of the lake’s northwest “arm,” about here. They were deformed so exquisitely during Andean mountain-building. Zoltán is a talented photographer, and you should check out more of his work here.


25 April 2019

How We Got To Now, by Steven Johnson

I was very impressed with Steven Johnson’s The Invention of Air when I read it last summer. So recently, I decided to sample another of his books, this one a six-part microhistory about innovations that altered the course of human history. The six are: 1) cleanliness/hygiene (specifically in medicine and drinking water), 2) measurement of time, 3) glass (think lenses!), 4) understanding of light, 5) refrigeration, and 6) the recording …


8 March 2019

Friday fold: Dent de Morcles

The Friday fold is a recumbent anticline/syncline pair, deforming the K/Pg boundary in the Swiss Alps, as photographed from the air by Bernhard Edmaier.


25 June 2018

Mafic volcanics atop felsic instrusives: Sonora Pass, California

Sonora Pass, California, is a lovely place to examine a volcanic-on-plutonic nonconformity that spans about 80 million years of missing time. Let’s check it out on a photo-rich virtual field trip!


24 April 2018

T. rex and the Crater of Doom, by Walter Alvarez

Walter Alvarez has a new book out, and its publication reminded me that though I read and appreciated The Mountains of St. Francis, I had never read his most famous work — the account of how he and his father and a team of other researchers zeroed in on an extraterrestrial impact explanation for the end-Cretaceous extinction. So last week I read T. rex and the Crater of Doom (1997). …


27 November 2017

Visiting the K/Pg boundary at Bottaccione Gorge, near Gubbio, Italy

A trip to one of the most famous outcrops in the world, a place with a stratum that marked a profound shift in the state of the planet, and a profound shift in geologic thinking. Plus, for the author, it’s a romantic journey back in time.


3 October 2016

A virtual field trip to Rathlin Island, Northern Ireland

Rathlin Island lies north of mainland Northern Ireland, a few miles offshore. I spent three lovely days there this past summer, investigating the geology and appreciating the wildlife (puffins and other sea birds, and seals). The geology is pretty straightforward: Paleogene basalt overlying Cretaceous “chalk” (really not so chalky here – technically, it’s the Ulster White Limestone). Here’s a suite of interactive imagery that you can use to explore Rathlin’s …


27 March 2016

Another trio of 3D models

Here are three more of my Photoscan-generated, Sketchfab-hosted 3D models of rock samples: Mud cracks in Tonoloway Formation tidal flat carbonates, Corridor H, West Virginia: [sketchfab id=”49cfc017248e44c2aa8b8bcdfa18facd” start=”0″ spin=”” controls=”0″] Diorite from the eastern Sierra Nevada of California: [sketchfab id=”36184956acb94476ae84569b8fbc300b” start=”0″ spin=”” controls=”0″] Vein cross-cutting foliated & lineated gneiss, Blue Ridge basement complex, Virginia: [sketchfab id=”1ebf2edc042d4cdf9493d0ff7963aff5″ start=”0″ spin=”” controls=”0″]


20 March 2016

3D and GIGAmacro views of Cerro Toro conglomerate

Six years ago, I went to Patagonia*, and collected this sample there. It’s a deep-water conglomerate from the Cerro Toro Formation. I’ve imaged it here in two media: the Sketchfab-hosted (Photoscan-generated) 3D model, and GigaPan-hosted (GIGAmacro-generated) views of both the front and the back. In combination, these three digital items can probably give you a pretty good sense of the sample: [sketchfab id=”7fe94fbacda948beaae4737afb2f589c” start=”0″ spin=”” controls=”0″] [gigapan id=”185276″] Link [gigapan …


4 December 2015

Friday fold: interference patterns on Elba

Samuele Jæger Papeschi shares one more fold with us: some deformation here… type III (Ramsay…) interference pattern in Cretaceous calcschists… Cavo, Elba Island Awesome! I hope everyone has a great Friday.


31 July 2015

Friday fold: a return to the duplex structure in the Gastropod Limestone

Some time ago, I featured as Friday fold the extraordinarily complex duplex structure to be seen in the Cretaceous “gastropod limestone” member of the Kootenai Formation at Sandy Hollow, Montana. Today, let’s take a deeper look through a couple of hand-shot GigaPan images: Here’s the bigger of the two: [gigapan id=”176119″] link Here’s one with students for scale: [gigapan id=”176475″] link


25 April 2015

Red Conglomerate Hills Near Oudtshoorn, South Africa

On Monday I shared a picture of a pretty conglomerate that I recently walked across. Today I thought that I would share a few more pictures of this conglomerate formation and also tell you a little more about it. Although in Monday’s picture the conglomerate looks somewhat dull-colored, the conglomerate formation is actually impressively red in color in many places, so much so that hills made of the conglomerate are …


20 April 2015

Monday Geology Picture: Conglomerate Near Oudtshoorn, South Africa

A couple of weeks ago I spent part of a weekend staying near Oudtshoorn, South Africa. During a hike, I walked by and, at times, across a beautiful Cretaceous age conglomerate. Here’s one image of the conglomerate, taken when I hiked across it. I’ll share some more pictures in another post.


19 December 2014

Friday Fold: Mist Mountain Formation in Canmore, Alberta

Let’s journey to the Cretaceous today, to see sandstones, shales, and even some coal strata that have been folded during the eastward thrusting that built the Canadian Rockies. Here’s the same fold, in context, shot in GigaPan on a different day, from a different angle. Can you match it up? [gigapan id=”159471″] link Ben Gadd showed me (and my field class) this site last summer. It’s a little west of …


16 April 2014

Turitella in Buda Formation limestone

Back to Texas, today. Here’s a cross-sectioned Turitella snail from the Buda Formation limestone: It’s exposed in a block of rock on the north side of Mt. Cristo Rey. You can explore these GigaPanned blocks of the Buda in search of your own Turitella… How many can you find? [gigapan id=”129425″] link [gigapan id=”129426″] link [gigapan id=”129424″] link


3 January 2013

Inside the French Thrust

Callan zooms in on the meso-scale structure of the French Thrust fault, exposed in Sun River Canyon, Montana.


24 November 2012

Rock Cycle III: Igneous → Sedimentary

The Boulder Batholith outside of Butte, Montana, is actively weathering, and shedding off grus. In the third installment of the Transitions of the Rock Cycle series, we watch an igneous rock turn to sediment.


3 August 2011

Gigapan of the French Thrust

To follow up on my March post on the French Thrust, here’s a gigapan of the outcrop. [gigapan id=”83267″] Sun River Canyon, Montana, of course: the Sevier fold-and-thrust belt.