Red Bluff Granite, and what it intruded into
Returning to his February field trip in west Texas, Callan examines the contact zone where the Red Bluff Granite intruded into a group of surficial rocks, including columnar-jointed basalt.
texas
Kink fold in Castner Marble
One more structure from the Castner Marble. This one is clearly tectonically-induced: Top to the left! (East over west)
Castner Marble
The Castner Marble is an extraordinary Mesoproterozoic limestone (later re-crystallized and metamorphosed) that exhibits some primary structures (both explicit and ambiguous) and some secondary (tectonic) overprints. It’s exposed in the Franklin Mountains of west Texas.
Slick!
Slickenlines (fault grooves) and fault polish on a chunk of sandstone in far western Texas.
One from the UTEP Reading Room
Incipient mylonitization of a granite/granitoid, as displayed in a sample on a shelf of one of the meeting rooms adjacent to the Reading Room of the Geological Sciences building at the University of Texas at El Paso. Same side, slightly different lighting conditions: I’d call this a protomylonite. Some of you might prefer the term … Read more
Mudcracks worth writing home about
Some sweet “columnar jointing” style mudcracks from an abandoned quarry in about the farthest west corner of Texas that you can get to, or maybe the southeasternmost corner of New Mexico. One of them, anyhow… Did you spot the imposter?
Plane views
A few scenes out the left side of the airplane from when I flew from El Paso to Houston a week and a half ago… Sand dune field overprinting desert vegetation and human roadways: Outcrop pattern of horizontal strata (tracing out the contours of this hill), and the weird geometry of human road systems: More … Read more
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.”
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.
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.
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 … Read more
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?
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.
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 … Read more
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 … Read more
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.
InTeGrate, and some UTEP folds
I’m in El Paso, Texas, today (and tomorrow and Saturday), collaborating on a massive brainstorming session for a new NSF-funded initiative called InTeGrate, which is all about Interdisciplinary Teaching of Geoscience for a Sustainable Future. As leader Cathy Manduca said today when she opened our session, “We’re here to save the world!” And we’re going … Read more