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18 February 2012
The xenobomb
Callan shows off a new sample from Texas, a peridotite xenolith launched into the air from a maar volcanic eruption, slathered in a layer of basalt. With full intent to coin a neologism, he dubs it a “xenobomb.”
17 February 2012
Friday fold, from in front of UTEP
Another sample from the collection on display, both indoors and out, at the University of Texas at El Paso. Don’t know anything about it beyond its lovely differential weathering. Happy Friday.
16 February 2012
Wyler Aerial Tramway and the Franklin Mountains of West Texas
Riding a cable-car up the side of the Franklin Mountains, Callan checks out the local stratigraphy and structure (and igneous intrusions). Join him on an insightful cruise up several thousand feet and through a billion years of geologic time.
15 February 2012
Colluvium-choked channel in cross-section
After seeing the contact of the Campus Andesite with Western Interior Seaway sedimentary rocks (Cretaceous in age), we moved a bit on down the line, and saw this disconformable contact between the Cretaceous shales below, and a bouldery sedimentary breccia above. Note the concave-up shape of the contact to the left of Elizabeth Nagy-Shadman (of Pasadena City College, California): that’s probably an old river channel scoured into the shale bedrock, …
14 February 2012
Contact of the Campus Andesite with host rocks
First thing we saw on the post-InTeGrate field trip to the rocks of El Paso, Texas, was this contact between the aforementioned Campus Andesite, and the Cretaceous sedimentary rocks into which it intruded (contact metamorphosed in the area of this photo): I decided to try switching up my annotation fonts. Whaddya think?
13 February 2012
Recumbent fold in Sierra de Juarez, Mexico
Callan looks south across the border from Texas. Above the drug-war-ravaged town of Juarez, the Sierra de Juarez Mountains feature an enormous recumbent synform.
12 February 2012
Fractures on a seismic sign
On the campus of the University of Texas at El Paso, there is a sign for the Kidd Seismic Observatory. The sign has seen some brittle deformation of its reflective letters. I infer this due be due to differential shrinkage of the letters (relative to the sign they are attached to) in the intense Texas heat. I like seeing deformation in materials other than rocks. This is a neat example …
11 February 2012
A campus underlain by porphyritic andesite
The campus of the University of Texas at El Paso is a beautiful place. You can look south into Mexico, a scant half mile away. It’s got rocky hills rising up between buildings and between stadiums (stadia?), and a utterly unique campus architecture based on the Himalayan nation of Bhutan. Here’s a look at the rocks beneath the university… The main rock type is a porphyritic andesite – probably a …
10 February 2012
Cuprified wood
This is insane. Check it out – a malachitized and azuritized log, on display in front of the Geological Sciences building at the University of Texas at El Paso: Have you ever seen anything like that? It’s cool meets cool. Awesome.
Friday fold: kinky limy laminae
From the road that keeps on giving: new New Route 55, in West Virginia, west of Moorefield.
Callan Bentley is Associate Professor of Geology at Piedmont Virginia Community College in Charlottesville, Virginia. He is a Fellow of the Geological Society of America. For his work on this blog, the National Association of Geoscience Teachers recognized him with the James Shea Award. He has also won the Outstanding Faculty Award from the State Council on Higher Education in Virginia, and the Biggs Award for Excellence in Geoscience Teaching from the Geoscience Education Division of the Geological Society of America. In previous years, Callan served as a contributing editor at EARTH magazine, President of the Geological Society of Washington and President the Geo2YC division of NAGT.