maryland

Documenting doomed outcrops: Scientists’ Cliffs, Maryland

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The community of Scientists’ Cliffs in Maryland is a private community that happens to sit on some of the most amazing fossil exposures in the Coastal Plain. The strata in question are part of the Miocene-aged (~14 Ma) Calvert Formation. The Scientists’ Cliffs outcrops are better than the more famous outcrops at Calvert Cliffs State … Read more

Snowball students visit the University of Maryland

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The final meeting of my spring semester Snowball Earth class was a field trip to the University of Maryland, hosted by Snowball guru Jay Kaufman, a specialist in chemostratigraphy using stable isotopes. Here, Jay welcomes the class to his wet lab: Doing chemostratigraphy takes lots of samples. Here’s a drawer full of samples from one … Read more

Aligned tourmalines

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…in an Archean schist within the Superior Craton. Same outcrop as the criss-crossing dikes I showed yesterday. We’ve got tourmalines on the plane of foliation in the Setters Schist in Maryland, too, but they aren’t aligned like these Canadian tourmalines; instead the Maryland ones are scattered willy-nilly across the plane of foliation, like pencils on … Read more

Turbidity in Chesapeake Bay

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Hurricane Irene passed this way two weeks ago, and dumped a lot of rain on the mid-Atlantic region and the northeast. As a result, runoff increased, rivers swelled, and sediment was mobilized. Some of that sediment was suspended and transported downstream. On Tuesday, I got this e-mail from my colleague Ken Rasmussen, who took students … Read more

Graded bed from the Billy Goat Trail

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Spotted this one Monday on the newly-rerouted section of the Billy Goat Trail’s Loop A, in Chesapeake and Ohio Canal National Historical Park. This graded bed was deposited as a turbidite in the Iapetus Ocean, sometime in the time-frame of 700 to 460 million years ago. It was metamorphosed 460 Ma during the late Ordovician … Read more

Two joints

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Stopped at Sideling Hill, Maryland, a few weeks back with my three Honors students, on our way to Pittsburgh for the northeast/north-central GSA section meeting. Robin took this photo of me with some sandstone beds that reveal two nice examples of joint anatomy, complementary in their structure: First focus in on the area right of … Read more

News from the Billy Goat Trail (3): grab bag

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Okay, a final post (for now, anyhow) sharing some images from last Friday’s field trip to the Billy Goat Trail, in Potomac, Maryland. Yesterday we looked at lamprophyre dikes, but there are other dikes on the Billy Goat Trail, too. Like this granite pegmatite: What’s interesting to me about this is that the joint set … Read more

News from the Billy Goat Trail (1): Graded beds

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I took my structural geology students out the Billy Goat Trail (upstream half of the “A” loop, near Potomac, Maryland) last Friday, and had them gather data for a project to assess whether or not Mather Gorge is controlled by a fault. I got this idea from Aaron Martin, the structural geologist at the University … Read more