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19 June 2013
My wonderfully named e-buddy Martin Bentley recently took a field trip to a quarry in South Africa (between Grahamstown and Fort Beaufort) where the Dwyka Formation is exposed: This poorly sorted sedimentary rock (a ‘diamictite’) is usually interpreted as glacial deposits (lithified till, or ’tillite’). Alfred Wegener cited these rocks and accompanying glacial striations (and similar ones in South Africa, India, Australia, and Antarctica) as evidence for the existence of …
18 January 2013
Callan watches the new documentary “Chasing Ice” about James Balog’s Extreme Ice Survey project, and spots a lovely Z-fold during the largest glacial calving event ever recorded.
21 August 2012
A few photos from the Canadian Rockies illustrated the characteristic “look” of glacial striations. Callan also demonstrates how they can be used for outright tomfoolery.
6 August 2012
Photo by Sarah O. Tune in tomorrow for the answer!
26 July 2012
Click through for a big version… That’s the Athabasca Glacier, crown jewel of the Icefields Parkway in Jasper National Park, Alberta, Canada. Its lateral moraines show well its retreat and “deflation” in recent years.
30 March 2012
Searching for Peter Luffi’s latest Where On Google Earth? challenge, I found myself touring Iceland last week. While I didn’t find the strange comet-shaped feature he posted, I did find this: And zooming in a bit, to the high-contrast area in the center: This appears to be volcanic ash layers distorted by glacial flow and then melting/sublimation/weathering/erosion/ablation of the glacier. I posted something similar as the Friday fold almost a …
19 August 2011
Callan’s answer to the riddle of the mystery outcrop is revealed. Spoiler: the glacier did it.
15 April 2011
The Friday fold is glimpsed from Google Earth. Atop a valley glacier in south-central Alaska’s Kenai mountain range, a fold of “transverse moraine” displays parasitic folds.
29 March 2011
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 the Laurentide ice sheet. We were there to look at the Pleistocene features, but several …