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31 July 2017

Great Surveys of the American West, by Richard A. Bartlett

After reading Passing Strange, I found myself wanting to learn more not only about Clarence King, but also about the other great surveys of the American West – those of Hayden, Powell, and Wheeler. I’ve read Powell’s account of descending the Colorado River, and I’ve been delighted this decade past to explore Hayden’s territory in the northern Rockies (but didn’t know the details of his work). Of Wheeler, I knew …

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4 May 2017

Passing Strange, by Martha Sandweiss

Clarence King was a legend. He led one of the four great surveys of the American west (along with Wheeler, Powell, and Hayden) and eventually convinced Congress to establish One Survey To Rule Them All, an institution that ended up being called the United States Geological Survey. King was its first director, but he didn’t last too long in that position before resigning so he could pursue his own mining …

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19 August 2016

Friday fold: marble, Kings Canyon, California

My friend Bill Burton (USGS, Reston) shared today’s Friday fold — Chevron folds in marble, Kings Canyon, California. Nice! Thanks for sharing, Bill!

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8 February 2013

Friday fold: LIDAR view of the Weverton Formation along the Blue Ridge front

Dan Doctor of the US Geological Survey contributed this week’s Friday fold. It’s a lovely view of the asymmetric folds in the Cambrian-aged Weverton Formation (part of the Chilhowee Group, a Sauk-Sea passive margin transgressive sequence), exposed on the western flank of the western limb of the Blue Ridge Anticlinorium. It’s a LIDAR image, and it’s best viewed when draped over the scenery in a Google Earth view. Here’s a …

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22 January 2011

Let’s coin a name for this phenomenon

I didn’t mention it yesterday, but there was one other structure that I saw at my newest outcrop on New 55. This is it: That’s a bunch of fractures. The broken rock is being altered by preferential fluid flow through the fractures. The fluid is not inert; it’s chemically active, and reacting with the rock. These reactions produce the color and weathering differences that you note in the previous images. …

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20 March 2010

Transect debrief 1: starting in the basement

It is time to debrief the post-NE/SE-GSA field trip that I went on, affectionately dubbed the “Transect Trip” for the past 27 iPhone-uploaded “live”-geoblogged posts. First off, I’d have to say that I enjoyed the live-field-blogging experiment overall, though I’ve got some critiques of the process and products. I think it’s amazing that I can upload photos and short blog posts from my iPhone to this site with a minimum …

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8 March 2010

Suevite from Vrederfort

One of my students brought this sample in the other day: She said her father collected it in South Africa. It was labeled “suevite.” I learned the term suevite about a year ago, while touring the USGS Chesapeake Bay Impact Crater coring project samples at the USGS Headquarters in Reston, Virginia. Wright Horton taught me that suevite is impact-generated melt that chills with other chunks of the pre-impact rock mixed …

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