Callan documents a geological stroll along the coast of Esterillos Oeste, in central southern Costa Rica, investigating the sequence of sediment in the Punta Judas Formation (Mid-Miocene) exposed there. Fossils, sedimentary structure, diagenetic features, structural deformation, and modern weathering all make prominent appearances.
A fun, if a little musty, compendium of random writings about geology and geologists from a wide variety of sources, excerpted and packed together into a slim paperback volume. It begins with Mark Twain and concludes with Russell Baker, and there are hundreds of entries in between – some poems, some short essays, some clipped … Read more
My favorite popularizer of modern geology is Marcia Bjornerud. Her sensibility for what is interesting and important matches very nicely with my own – I feel she is a kindred spirit, though one infinitely more talented with language than I am. Lovers of geology found much to delight them in Reading the Rocks. She took … Read more
This memoir by one of America’s earliest female geologists is an enjoyable read about adventure and professional working conditions in the 1920s and 1930s, and up though the 1950s and 1960s. Fowler-Billings (née Fowler) led an interesting life, ranging from growing up in an urban Boston that still had a significant horse population to post-retirement … Read more
[Note: this book review was scheduled to run in the July 2019 issue of EARTH magazine, but with the announcement two weeks ago that EARTH was being shuttered, I was notified that nothing contributors or freelancers had written scheduled for after April 2019 would be published, and the rights were returned to me. While that’s … Read more
I love the “Geology Underfoot” series published by Mountain Press – the same folks who have published dozens of titles under the “Roadside Geology” theme. “Underfoot” is better than “Roadside,” I think, because it tells the story of discrete places, suggesting ideal places to visit. Each chapter is self-contained and useful without extraneous details, and … Read more
I got a call last month from Rebekah Wiedower, a landowner up in Frederick & Clarke counties (her family’s property includes pieces of both), inviting me to come up and look at some anticlines and synclines that Dan Doctor (USGS) had identified on the bank of Opequon Creek. I was glad to do it, though … Read more
The cover story in the November issue of GSA Today was by David Montgomery, MacArthur “genius” award winner and author of Dirt. Montgomery has a new book out on creationism and “flood geology,” and the article is a précis of the historical roots of creationism that appears in that book. The article is titled “The … Read more
Callan reviews a new book by Doug Macdougall: “Why Geology Matters.”
Shawn at the blog Vi-carius is hosting this month’s Accretionary Wedge. He asks for a geoblogosphere-wide brainstorm on “dream geology courses” – an inspirational topic! I have a few ideas: A travel course dedicated to exploring the roots of geological thinking and the geological timescale. It would clearly need to be based in the U.K. … Read more
I just finished reading 101 American Geo-Sites You’ve Gotta See, one of the latest publications by geology-friendly (and Missoula-based) Mountain Press. I’m grateful to the the publishers for sending me a review copy. It’s a nicely written and produced book highlighting sites across the United States of America of geological interest. The book is organized … Read more
Last weekend, my wife and I joined friends for a weekend of cross-country skiing in the wonderful Canaan Valley of West Virginia. On the way back, between the towns of Burlington and Romney, West Virginia, I saw this folded shale on the north side of Route 50: You can click on that panorama to make … Read more
Here’s two nice examples of mudcracks I saw used as paving stones in South Africa:
Site of the mystery photo I posted over the weekend, the beach at Rooiels (“red grass” in Afrikaans), South Africa, is a lovely place… Located on the western side of False Bay a tad north of Cape Hangklip, Rooiels is somewhat famous in my mind because the Guru of Gigapan, Illah Nourbakhsh, spoke glowingly of … Read more
Callan reviews the geology of the superlatively auriferous Witwatersrand Supergroup of South Africa, and then zooms in on a distinctive marker bed near the base of the sequence. The deformation in this particular banded iron formation (BIF) is an aesthetic wonder, as this suite of images reveal. The layer outcrops in the heart of urban Johannesburg.
Picking up from the astonishing first couple of outcrops we saw of strained Seine Group metaconglomerate from the boundary between the Wabigoon and Quetico sub-provinces of the Superior Craton, our group moved on down the road. It was lovely clear fall weather near Fort Frances, and shockingly warm. Our third stop of the morning was … Read more
While out in the field with Butch Dooley last week, making major discoveries like I do, I was very impressed with the landscape-scale west Bighorn monocline, which takes formerly horizontal Madison limestone and skews it to a westward dip where the mountains end and the intermontane basin begins. It’s totally sweet. Check it out in photo form and gigapan, too.
Callan visits the grave of John Wesley Powell, second director of the USGS and explorer of the Grand Canyon, on an afternoon in Arlington National Cemetery.
Yesterday afternoon, I spent some time in the field with a colleague, a student, and a gigapan. I took four gigapan images, which are of varying quality due to the partly cloudy day, but still you ought to find them interesting to explore. You can see any of them full-screen by clicking on the word … Read more
Another group of interesting cobbles from the same sand and gravel pit that I described earlier in the week: Here’s the same sample, gone all animated, for your perspectivizing pleasure: What we’re seeing here is some fine-grained gray colored rock (siltstone, I guess?) that’s developed a pronounced weathering rind marked by a large amount of … Read more