eocene

Green River Formation stromatolite – a virtual sample

by

Today concludes a weeklong run of virtual samples. For the past five days, I’ve been presenting examples of a visualization combination that leverages the advantages of the GIGAmacro system with the 3D ‘virtual sample’ perspective of the Sketchfab-hosted model: the same sample presented in both formats. Today, we finish up with a stromatolite from the hypersaline … Read more

Deformation associated with the intrusion of the Muleros Andesite

by

Yesterday, I showed off a few views of the contact between the Cretaceous aged Mesilla Valley Formation shale and the hypabyssal Muleros Andesite which intruded into it during the Eocene at Mt. Cristo Rey (on the US/Mexico border where Texas meets New Mexico). Today, I’d like to look at some of the structure associated with … Read more

Contact between Muleros Andesite and Mesilla Valley Formation shale at Mt. Cristo Rey

by

There are two rock units in this photo. One is igneous, one is sedimentary. Can you find the contact between them? It’s somewhere along this dashed line… The Mesilla Valley Formation is Cretaceous shale with some sandstone. The Muleros Andesite (pretty much identical to the Campus Andesite you find at UTEP) is Eocene. Here’s a … Read more

Friday fold: Another from Cristo Rey

by

The laccolith of Cristo Rey, at the Chihuahua / Texas / New Mexico triple point, is host to some cool geology. It’s cored by the Campus Andesite (47 Ma, Eocene) but surrounding the intrusion are a slew of sedimentary rocks, include the Turitella-bearing limestones of the Buda Formation and the shales and sandstones of the … Read more

Stromatolites of the Green River Formation

by

The summer before last (2011), I spent some time in Wyoming on an energy resources field trip run by Sheridan College, and one stop we made was to look at “oil shale” (really kerogen-rich marlstone) of the Green River Formation, an Eocene lake deposit in southwestern Wyoming. The oil shale is exposed on the east … Read more

Pebble Creek memories

by

This summer is the first summer in half a decade that I won’t be spending time camping at Pebble Creek campground, in the Lamar Valley of northeastern Yellowstone (“America’s Serengeti”). While I’m very excited to be nesting and exploring my new home in the Fort Valley, it does make me a bit wistful to think … Read more

Macro GigaPans of Florissant insect fossils

by

Today, for your viewing pleasure, please check out five macro GigaPans of insect fossils from the Florissant fossil beds in Colorado (34.07 +/-0.10Ma). These amazing specimens were collected by Joe Cancellare, a student working on research supervised by Josh Villalobos of El Paso Community College in El Paso, Texas. Our M.A.G.I.C. project is helping Joe … Read more

Contact of the Campus Andesite with host rocks

by

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?

Clinker

by

“Clinker” is an interesting rock type seen in Wyoming’s Powder River Basin. It forms when a coal seam catches fire, and cooks the rock above and below it, including the potential for partially melting the strata immediately above. Check out a few images of this intriguing rock here.

Block Mountain basalt flow

by

This year, for the first time ever, I took students to map at Block Mountain, a classic field camp mapping site near Dillon, Montana. Here’s a quick look (enlarge it by a gazillion-fold by clicking through) of some columnar jointing in the Eocene Block Mountain basalt flow, a paleo-drainage turned mountain through the miracle of … Read more

A portrait of the feldspar as a young mineral

by

A few microscope photos for you, showing close-ups of feldspars in igneous dikes in the Crazy Mountains of Montana… You’ve seen these rocks before, when I posted a few field photos from this area in August 2009. I took these images of feldspar phenocrysts in a hand sample (from a quartz latite dike) with my … Read more

Gerede segment of the North Anatolian Fault

by

The author recounts a field trip in October along the section of Turkey’s North Anatolian Fault that last ruptured in 1944. The rock types on either side of the fault are compared, offset markers are illustrated, and several types of landforms particular to strike-slip faults are shown. The post concludes with an examination of the town of Gerede itself, which is built directly atop the fault.