Advertisement

You are browsing the archive for glaciers Archives - Page 2 of 4 - Mountain Beltway.

18 July 2015

Purcell Sill → Dike, Grinnell Glacier Cirque, Montana

The Neoproterozoic Purcell Sill is a stark, obvious black stripe in the strata of Glacier National Park. Here it is emerging from behind “The Salamander” glacier, above Grinnell Glacier Cirque: Zooming in, you can see the “baked” (bleached) zones above and below this concordant intrusion. But this time, during my visit to this special place, I noticed a discordant offshoot from the main sill: See it? Up there at the …

Read More >>

No Comments/Trackbacks >>


19 June 2015

Friday fold: subglacial drag fold (Pleistocene) in Cretaceous sediments, Alberta

Howard Allen, a retired petroleum geologist from Calgary, and longtime reader of this blog, contributed this week’s Friday fold: Subglacial drag fold (Pleistocene) in Upper Cretaceous Horseshoe Canyon Fm. bedrock (sandstone, shale). The locality is SE of Drumheller, AB at UTM 12U 394247 5692469 (WGS84). Did you hear that right? Yes, you did: This is Cretaceous aged sedimentary rock, folded by a Pleistocene glacier, tens of millions of years after …

Read More >>

1 Comment/Trackback >>


16 March 2015

Mechum River Formation, near Batesville, VA

A quick virtual field trip to the Neoproterozoic glaciogenic sedimentary rocks from the central Virginia Blue Ridge province: Can you feel the chill of Snowball Earth?

Read More >>

3 Comments/Trackbacks >>


7 January 2015

A mafic sill in Antarctica

My friend and colleague Lauren Michel, the King Family Fellow at the Perot Museum of Nature and Science in Dallas, Texas, sent me this image from her recent trip to Antarctica: (click to enlarge) This is a beautiful example of a mafic igneous sill, probably of the rock known as “dolerite” (or diabase, to us Yanks). Lauren and I think it must be part of the Ferrar Large Igneous Province. …

Read More >>

1 Comment/Trackback >>


28 October 2014

Glacial striations

Today, I thought I would share some images of lovely “textbook” glacial striations from rocks I saw in the Canadian Rockies this summer…

Read More >>

No Comments/Trackbacks >>


4 July 2014

Friday fold: Warspite Anticline

A final guest Friday fold from reader Howard Allen, who I’m pleased to be meeting up with in Banff late next week… Howard writes the following in describing this lovely scene: Warspite Anticline, Peter Lougheed Provincial Park, Alberta. Photo is a telephoto shot (hence the strong blue alpine haze–the colour cast is an accurate rendition of the original daylight Kodachrome slide), looking southwest at an angle to regional strike. The …

Read More >>

1 Comment/Trackback >>


29 May 2014

A new diamictite exposure (Devonian?) along Corridor H

While on Corridor H last week with Team “Border to Beltway” (and USGS research geologist Dan Doctor), we stopped at the putative mass transport deposit. We still haven’t figured out which unit this is (It’s not the Foreknobs), but as we approached it, Dan wondered aloud, “I wonder where the top of the Devonian is. Maybe we could find some of Dave Brezinski’s glacial deposits.” If you’re not aware of …

Read More >>

9 Comments/Trackbacks >>


29 August 2013

Guest post: Glaciation in the Tetons

This is the fourth of several guest posts that appear here this week, all written by students who participated in this past summer’s Regional Field Geology of the Northern Rocky Mountains course. by Tony Robinson Old Dominion University

Read More >>

No Comments/Trackbacks >>


19 June 2013

Dwyka Tillite in South Africa

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 …

Read More >>

6 Comments/Trackbacks >>


18 January 2013

Friday fold: “Chasing Ice”

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.

Read More >>

No Comments/Trackbacks >>