A guest post by Callan’s student Jacob Douma Traveling with Callan Bentley and Pete Berquist through the Canadian Rockies on their Regional Geology Field Course in July 2012, we were exposed to a variety of physiographic features. Among them, was Red Rock Canyon located 16 km from Waterton Townsite within Waterton Lakes National Park, Alberta. … Read more
Callan presents a mystery rock found in blocks of sedimentary rock on a talus slope near the Consolation Lakes in Banff National Park, Alberta. Are they orange oncolites? Or alien embryos? 🙂
Ever seen an armored mud ball? In this post, Callan encounters a small herd of these geological oddities in a coulee in southern Alberta.
Yesterday, I showed you a scene of geologists (including me) clustered around some (presumably interesting) outcrop. I asked what you thought we might be looking at. Howard Allen, a denizen of this part of the globe, immediately identified the scene as that of the downstream end of the Athabasca Glacier. Several people guessed that we … Read more
Yesterday I showed you salt casts; today I’ll share a different kind of cast: the infillings of small scorings in the sediment made by tumbling pebbles or sticks or other “tools,”tumbling down a current. These small gouges were later infilled from above by a younger deposit of sediment (frequently coarser in grain size). You’re looking … Read more
I’ve previously mentioned the lovely salt casts that can be found in Mesoproterozoic argillites of the Belt (“Purcell” in Canada) Supergroup of the Canadian Rockies (including the North American portion of the Canadian Rockies: Glacier National Park and the Sevier fold and thrust belt immediately south of it). When I led my Rockies field class … Read more
A showcase of geologic structures observed between downpours of rain at Floe Lake, Kootenay National Park, British Columbia. Cleavage, bedding, folds, faults, and strain are all presented for the discerning structural reader’s edification and titillation.
After our “pre-honeymoon” sojourn to the Canadian Rockies last summer, Lily and I returned to the U.S. via Porthill, and then drove over to a place I’ve been wanting to visit for a long time: Yaak, Montana. Yaak (or “the Yaak“) is way up in the Kootenai National Forest, in way-way-way-northwesternmost Montana. We camped out … Read more
Callan presents a collection of well-exposed amygdules, seen along the Dark Hollow Falls trail in Shenandoah National Park, Virginia. These white dots on a green background are the signatures of (1) Iapetan rifting, and (2) Alleghanian metamorphism.
Yesterday, I introduced percussion marks to this blog space. Here are some other shots of this distinctive “shatter” structure, but in a vein of hydrothermal (milky) quartz exposed on Bear Island, between the C&O Canal and the Potomac River (about right here, just west of the trail): Sometimes percussion marks are accompanied by radial fracture … Read more