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Big Rock: The Okotoks Erratic
30-OCT-2005 © Gary Hebert

Big Rock: The Okotoks Erratic

Alberta Foothills

This image is best viewed at PBase "ORIGINAL SIZE".

This enormous quartzite block, weighing about 16,500 tonnes and measuring about 41 x 18 x 9 metres, was carried here on the surface of a glacier. It came from the Rocky Mountains in the Jasper area, probably between 18 and 10 thousand years ago. Rocks moved many kilometers from their original location by the ice are called “glacial erratics”.
Big Rock began its journey when rockslides in the mountains deposited quartzite debris onto the top of a glacier in the Athabasca River valley. The glacier carried the rocks with it as it flowed slowed eastward to the plains, until it collided with the Laurentide ice sheet. This massive ice sheet deflected the glacier to the southeast, parallel to the mountain front. When the ice melted, a string of erratics was left in a narrow belt extending from Jasper National Park along the foothills to northern Montana. This group is known as the Foothills Erratics Train, and the Okotoks Erratic is the largest member.
The name of the rock was derived from the Blackfoot word for rock: okatok.

Olympus C-8080WZ
1/40s f/8.0 at 8.3mm iso50 full exif

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Buz Kiefer01-Nov-2005 14:34
Very nice image and explanation of erratics Gary. The continental glaciers didn't get to the Smokys but they did bring us something. As the ice sheets advanced slowly and inexorably, they pushed the forest out before it. Our Canadian type forest, the spruce and fir of the Smoky high country, was brought here during the last Pleistocene advance. They did very well for over 10,000 years until acid rain and the balsam woolly adelgid hit them.

Now as for that marble you saw in today's photo... :^)
Focus31-Oct-2005 22:42
Nice shot.......beautiful.
SageCreek Images31-Oct-2005 20:59
Nice shot and light...it is astounding what nature can do...many marvels of nature exists in and around my area that was a direct cause of the glaciers....
Olaf Herrig31-Oct-2005 20:35
Excellent photo with an wonderful light.
JW31-Oct-2005 19:00
Wonderful picture. The rock texture is in perfect contrast to the blue sky.

I visited Okotoks last year, but was unaware of this interest phenomenon.
Rochelle Cardinale31-Oct-2005 18:31
Even if I wasn't a geologist who liked rocks, I would still love this photo. Wonderful capture and DOF.