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
Today, for your viewing pleasure, I offer you: A series of big honkin’ gas pockets in a 615 ka basaltic lava flow in the Owens Valley of California. This same lava flow has been featured here before, since it imparted a lovely contact metamorphism to the alluvial fan over which it erupted. These things are … Read more
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
Why are these geologists all over these rocks? Because, gentle readers, these are some seriously cool rocks. The geologists are all participants on a pre-GSA-annual-meeting field trip to the Superior Craton, a chunk of ancient crust at the “nucleus” of the North American continent. The rocks are syn-tectonic volcaniclastic conglomerates of the Seine Group. They … Read more
Callan’s answer to the riddle of the mystery outcrop is revealed. Spoiler: the glacier did it.
Hoo boy. This one made me yelp… While on the glacial geology of western Pennsylvania trip last Saturday, we visited a gravel quarrying operation. The operators were extracting gravel from a glacial lake delta deposit, and it was full of glacial outwash — sediments washed out from the melting front of the Erie lobe of … Read more
That title sounds kinky, right? Well, calm down. I’m behind the curve on the latest Accretionary Wedge (as I was for the one before that), but here’s a quick image to join the parade of geologic photos that Ann is hosting. While it’s not my favorite, it’s definitely a favorite, more by virtue of the … Read more
The penultimate episode of Callan’s more-than-a-week-long series on the geology of the San Francisco region: today we briefly visit the sand dunes that covered San Francisco Peninsula during the Pleistocene.
Quite appropriately, Glacial Till won the new the latest edition of “Where on (Google) Earth?”, hosted here yesterday. The location I picked is the subject of a new paper by Mark Johnson and colleagues appears in the current issue of Geology (October 2010). It shows a place in Iceland where a piedmont-style outlet glacier called … Read more
In the American Museum of Natural History: These mylodontids reminded me of Puerto Natales…