#lewis thrust

[earthstory]

The Lewis Overthrust

Named after the explorer Merriwether Lewis (as in the Lewis & Clark expedition), these peaks are the leading edge of the Rockies, thrust along a fault over younger rocks during the intense squeezing associated with mountain building. The rocks here form a nappe, a huge layer of rocks that detached (usually along a mudstone contact with harder sedimentary rocks) and was pushed up and along to accommodate the tectonic stress.

Running from Montana (including Chief mountain, see http://tinyurl.com/m5gc54a) north into Alberta, the thrust fault has been extensively studied in order to understand mountain building processes. The rocks are well preserved, and were conveniently carved by glaciers during the ice ages of the last couple million years into ready made cuttings, exposing the layers for the eager geologist. The entire front rises around 12-1500 metres above the Great Plains. The overthrust started around 170 million years ago as exotic terranes docked into the North American plate to form the current western USA. The wedge of rock was pushed 80km east by the pressure, and shoved over Cretaceous rocks that are a full 1.4 billion years younger.

Loz

Image credit: Bobak Ha'Eri

[earthstory]

Moraine Lake

One of nature's many wonders in Banff National Park, Canada's oldest, is a beautiful blue lake surrounded by the Rocky mountains in the Valley of Ten peaks. It is fed by glaciers, and blocked off by what is probably a debris slide from the nearby Tower of Babel and somewhat redistributed by glaciers rather than a normal moraine, but whatever the geological answer to this question, its loveliness is undeniable. Sitting at 1,885 metres, the surrounding peaks culminate in the 3,200's.

Moraine lake peaks in late June, when maximal snow and ice melt run down the catchment area, and when full it is a lovely chalky blue-green, due to light refraction by its rock flour content. The latter consists of highly pulverised particles of glacier ground rocks. The valley in which it sits is a typical u shaped glacial valley. It has become a national icon, this view being known as 20 dollar view after being featured for a decade on the back of a banknote.

The rocks here are sedimentary, deposited on the continental shelf that lay off the old edge of the America, and were compressed upwards by the Laramide orogeny when further chunks of continental crust accreted to the western coast pushing the old sea bed before it. They date from the Precambrian (600 million years old) to the Jurassic. There are some Cretaceous rocks, though these were formed by the erosion of new born mountains further to the west rather than deposited in a shallow sea. The mountain's main growth spurt was between 120 and 80 million years ago. Most of the landscape was sculpted by ice over the last couple of million years.

There are many nice hiking trails through the area, for all lengths and abilities. Beware though, there are grizzly bears, before hiking make sure you know what to do should you meet one. If you don't hike, watching the changing light and play of cloud shadow for a day from this spot would be more than stupendous enough.

Background mountains from left to right: Tonsa (3057 m), Mount Perren (3051 m), Mount Allen (3310 m), Mount Tuzo (3246 m), Deltaform Mountain (3424 m), Neptuak Mountain (3233 m)

Loz

Image credit: Gorgo

http://www.mountainnature.com/geology/LandformResult.asp?ID=15&CommonName=Moraine+Lake http://www.pc.gc.ca/eng/pn-np/ab/banff/activ/randonee-hiking/lakelouise.aspx http://www.albertawow.com/hikes/Moraine_Lake/Moraine_Lake.htm

[earthstory]

Original caption:

The Road Trip Story.. This was my favorite trip I've ever done and was so lucky to spend it with such amazing people. My hope with this video was to capture at least a fraction of the good times we had, and to have this to look back on fondly for years to come.

►Email: [email protected]

Details of the Production: ►Main Camera: Panasonic Lumix GH4 ►Lenses Used: Lumix 12-35mm f2.8 + Lumix 25mm f1.7 ► Edit Program: Final Cut Pro X ► Music: -Song 1: Simon May - Waiting (ft. Matilda Lucas) Simon May: soundcloud.com/simon_may -Song 2: TLATW - Light Waves TLATW: soundcloud.com/lighthouse-and-the-whaler Song 3: Laire - Final Coming Laire: soundcloud.com/laire ►Script: Part 1: "Driving over 24 hours in search of the most beautiful landscapes we could imagine. Waking up at first light. Staying up for last light. Camping together and sharing a road trip experience with other photographers. This is something I've always wanted to do. This is the Banff and Glacier road trip." Part 2: "We spent the next several days exploring Banff and the surrounding area, and I have to say, I've never been somewhere with so much natural beauty in all my life. I don't think there are many situations that make me happier, than running around incredible landscapes like these ones, camera in hand, and with great friends by my side."

A Travel Film by: Michael Bliss Thank you for watching.

[earthstory]

Crowsnest Mountain

This lonely peak in Alberta, Canada is a Klippe. It is formed by the huge Lewis Thrust system, a major fault in the Rocky Mountains of Canada and the US. That fault brings older rocks from deep up and sets them atop Cretaceous aged sedimentary rocks. At this site, the rocks lifted up by the Lewis Thrust are sediments formed in the Devonian and Mississippian eras, when ocean levels were high and sediments were deposited on the continents. A Klippe is a solitary mountain where the rocks are “out of order”. In this mountain, older rocks sit atop younger rocks. A huge thrust fault sheet once covered this entire area. Today most of the giant sheet of rocks that once sat at this site has been eroded away and it is instead found far to the west. Crowsnest Mountain is the tiny bit of this thrust sheet that hasn’t yet eroded away, and the Lewis Thrust can be found on the mountain’s face close to the tree line. That fault is the single layer or single plane that separates the older rocks above from the younger rocks below.

-JBB

Image credits: http://bit.ly/2AUC1sM http://bit.ly/2hQSkDb

Reference: http://www.summitpost.org/crowsnest-mountain/305340

[earthstory]

This part is the “Many Glacier” area of Glacier National Park. The opening frame is Chief Mountain - a Klippe, a type of outcrop that was uplifted on a fault but where almost all the surrounding rocks have eroded away. This clip provides some great zoomed in views of the sedimentary rocks that make up the fault. The big mountains are part of the Belt Supergroup, a huge deposit of Precambrian Aged Sediments that formed in a rift basin about a billion years ago. Those sediments were uplifted along a structure called the Lewis Thrust as the Rocky Mountains grew during the Jurassic and Cretaceous. There’s one really good shot of the Lewis Thrust in this clip - it’s a horizontal line where the rocks above and below look distinctly different (they are, they’re different in age by about a billion years).

[earthstory]

Well, if I’m going to be in Montana for a month I may as well let you enjoy some of it with me. Today should be my first day out in the field. The Montana Office of Tourism prepared a series of 7 videos exploring the landscape of one of my favorite parts of the country, Glacier National Park. This afternoon let’s go through...I dunno...ALL OF THEM. 

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I always love shots of Glacier National Park, such a majestic area.

[earthstory]

The Lewis Overthrust

Named after the explorer Merriwether Lewis (as in the Lewis & Clark expedition), these peaks are the leading edge of the Rockies, thrust along a fault over younger rocks during the intense squeezing associated with mountain building. The rocks here form a nappe, a huge layer of rocks that detached (usually along a mudstone contact with harder sedimentary rocks) and was pushed up and along to accommodate the tectonic stress.

Running from Montana (including Chief mountain, seehttp://tinyurl.com/m5gc54a) north into Alberta, the thrust fault has been extensively studied in order to understand mountain building processes. The rocks are well preserved, and were conveniently carved by glaciers during the ice ages of the last couple million years into ready made cuttings, exposing the layers for the eager geologist. The entire front rises around 12-1500 metres above the Great Plains. The overthrust started around 170 million years ago as exotic terranes docked into the North American plate to form the current western USA. The wedge of rock was pushed 80km east by the pressure, and shoved over Cretaceous rocks that are a full 1.4 billion years younger.

Loz

Image credit: Bobak Ha'Eri