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1 December 2010
The Konnarock Formation
A detailed description of one of the Virginia Blue Ridge’s most intriguing geologic formations: a maroon sedimentary sequence showing the advance of “Snowball Earth” glaciers in the Neoproterozoic.
17 October 2010
Birthing a litter of drumlins
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 Múlajökull is pooching out to the southeast from the Hofsjökull ice cap. Here’s a more …
29 April 2010
Mineral phantasms?
Ice… serpentine… halite… What do they all have in common? I’ve discussed mineral “ghosts” here before — really, those are only pseudomorphs, where one mineral’s chemistry becomes unstable due to a change in conditions, and then a new mineral forms in the same space. I’ve also brought up the issue of clasts of minerals which are unstable over the long term (ice). Last night, at the final meeting of the …
14 April 2010
Photos from Eyjafjallajökull
My friend Barry R., now residing in PostDocVille, Denmark, took a trip to Iceland last week to check out the eruption of Eyjafjallajökull. Unfortunately, by the time he got to the volcano, it was no longer spouting lava, but the scene is dramatic regardless. You can sample some of his photos below, or see the whole album on Facebook. Waterfall: Glacial terminus and moraine: Ash on ice (steam rising beyond …
8 March 2010
When the Sturtian happened
Last Friday, I spent the evening riding up to New York on a bus. To pass the time, I had my iPod and a new paper by Francis Macdonald and colleagues in Science. The paper examines the timing of one of the episodes of “Snowball Earth” glaciation. There’s some important new data in this paper, and it helps constrain the “Sturtian” glaciation in time. So here’s the deal with Precambrian …
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.