You are browsing the archive for mesoproterozoic Archives - Page 3 of 5 - Mountain Beltway.
26 October 2012
Friday fold: South African gneiss
Another Friday, another fold. …By another Bentley!
14 September 2012
Friday fold: Siim Sepp’s SS
Geoblogger Siim Sepp contributed this lovely fold. He says: I saw a nice fold in Ireland. I like it because it looks like SS to me which are my initials. If you want, you can post it as your friday fold. I haven’t used it yet in my blog. This small outcrop is in Donegal, NW part of Ireland. I accidentally stumbled upon it. The fold formed most likely during …
6 September 2012
Ribs & hackles
Concentric ribs with hackles on a joint face, quartzite (metamorphosed fine-grained quartz sandstone stained with hematite) from Waterton Lakes National Park, southern Alberta.
28 August 2012
Guest post: Red Rock Canyon
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. In this guest blog post, I’ll be talking about the canyon’s physiographic features and origins. …
2 August 2012
Weathering rind
A cobble of green Belt/Purcell argillite, exposed on the trail to Crypt Lake in Waterton National Park, Alberta, displaying a well-developed “weathering rind”:
23 July 2012
Salt casts from Purcell (Belt) Supergroup rocks, Waterton National Park
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 students over Alderson Pass / Carthew Summit in Waterton Lakes National Park, Alberta, last week, …
6 July 2012
Friday fold: scenes from the trail to Bertha Lake
Given that I’m leaving tomorrow for the Canadian Rockies, I’ve been inspired to look through some of my photos from last summer, and to realize how few of them I’ve blogged so far. So let me show you some folded things today that Lily and I saw the afternoon we arrived at Waterton Lakes National Park in southernmost Alberta: Here’s a fold on the side of a mountain on the …
30 May 2012
Virginia geology on video: The Grenville Orogeny & the rifting of Rodinia
I’m playing around with Microsoft Expression screen capture for the book project I’m working on, and here is a video I worked up yesterday as a demonstration of this new way of telling a geologic story: The Grenville Orogeny and the rifting of Rodinia (opening of the Iapetus Ocean): [youtube=”www.youtube.com/watch?v=g6itZWD8bQc”] I’m frustrated by the way my voice keeps blowing out the microphone, and how often I say “um” and how …
24 April 2012
Visiting the Swift Run
I took my structural geology students to that fine outcrop of the Swift Run Formation in eastern Shenandoah National Park on Friday. There, we saw lovely primary structures with tectonic fabric overprinting (as I have showcased here previously). Consider this graded bed with subsequent (vertical) cleavage: And here’s the hinge of a nice passive fold, bearing well-developed axial plane cleavage: Annotated: Close-up of the cleaved central bed:
5 April 2012
Red Bluff Granite, and what it intruded into
Returning to his February field trip in west Texas, Callan examines the contact zone where the Red Bluff Granite intruded into a group of surficial rocks, including columnar-jointed basalt.
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.