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 … Read more
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.
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.
Photo by Sarah O. Tune in tomorrow for the answer!
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.
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 … Read more
Callan’s answer to the riddle of the mystery outcrop is revealed. Spoiler: the glacier did it.
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.
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
Saw this beauty on a field trip Saturday, examining the glacial geology of western Pennsylvania. Note the faceted surfaces and profusion of scratches of multiple sizes in multiple orientations.