3 July 2015

Friday fold: Opal Range, Alberta

Howard Allen is the Friday folder who keeps on giving… Here’s his latest:

Multiple folds at top of ridge, Opal Range, Alberta. Photographed from Kananaskis Highway 40, looking SE. Beds are Carboniferous carbonates, probably Mount Head and/or Etherington formations.

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There are lots of great folds to be seen along that road. The Kananaskis Trail is in the “tourist shadow” of the nearby Trans-Canada Highway, which means it’s well worth your time to drive it if you ever find yourself in the southern Canadian Rockies.

Happy Friday!

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26 June 2015

Friday fold: Subvertical carbonates

Another Friday, another Friday fold from Howard Allen:

Folds in near-vertical beds, north side of Grizzly Creek, Opal Range, Alberta. Beds are Carboniferous carbonates, Mount Head and Etherington formations.

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Enjoy your day!

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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).

Glacial drag fold in bedrock, road cut, Hwy 573, east of Willow Creek Hoodoos, SE of Rosedale, Alberta

Glacial drag fold in bedrock, Hwy 573, east of Willow Creek Hoodoos, SE of Rosedale, Alberta

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 it was deposited. And a massive tongue of ice did it!

Here’s another perspective on the same fold, looking roughly along (regional) strike to north, the direction from which the Laurentide ice sheet moved:

Glacial drag fold in bedrock, road cut, Hwy 573, east of Willow Creek Hoodoos, SE of Rosedale, Alberta

Glacial drag fold in bedrock, Hwy 573, east of Willow Creek Hoodoos, SE of Rosedale, Alberta

A very happy Friday to you!

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12 June 2015

Friday fold: Flow banding in obsidian, Newberry Volcano National Monument, Oregon

Lockwood Dewitt is the purveyor of this week’s Friday fold ensemble:

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All these folds are primary (not tectonic) in nature: they are flow banding of the viscous lava that oozed out to make the Big Obsidian Flow at Newberry.

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And closer in:

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One more:

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Awesome stuff! Thanks for sharing, Lockwood!

Happy Friday, everyone!

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29 May 2015

Friday fold: Hayward neighbor

Reader Bill Mitchell contributed this week’s Friday fold, viewed here zooming in closer and closer over three photos:

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Bill says:

Here we have a fold found along a trail in Strawberry Canyon just east of the University of California, Berkeley and the Hayward fault. It seems to be mapped (http://pubs.usgs.gov/mf/2000/2342/) as Cretaceous undivided (Great Valley sediments), but I wouldn’t be surprised if it were Claremont Chert (late to middle Miocene) or Claremont Shale (late Miocene). Superficially they are similar to the type section of the Claremont Shale, found just a canyon or two over, and perhaps too small to show on the geologic map.

Bill is on Twitter too: @i_rockhopper

Thanks for the contribution, Bill!

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22 May 2015

Friday fold: Welsh carbonates

Kate Littler sent in this Friday fold, via Twitter:

lovely parasitic folds in the Carb limestone,  West Angle Bay south Wales.

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Awesome. Looks like a great place. Thanks, Kate!

Happy Friday!

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21 May 2015

Soft sediment deformation in sandstone and shale, Bolt Mountain

Today, I’ll treat you to two examples of soft-sediment deformation from the Kanawha Formation on Bolt Mountain, West Virginia…

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#2:

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This cross section looks very much like the 3D “sled” shapes to the soft sediment deformation “ploudins” at Corridor H

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20 May 2015

Liesegang banding in Pennsylvanian sandstones, Bolt Mountain, West Virginia

While out at the eastern section of NAGT’s annual meeting last weekend in West Virginia, I participated in a field trip to look at the stratigraphy of the Bolt Mountain section of Pottsville Group strata. One thing that was particularly eye-catching about the sandstones we saw was that many of them had been stained by rusty groundwater, producing the lovely stripey pattern known as Liesegang banding. Here are five examples:

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Here are some previous examples of Liesegang banding here on Mountain Beltway. It’s lovely stuff.

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18 May 2015

Spheroidal weathering in sandstone

Here’s a nice example of spheroidal weathering in a sandstone, developed using orthogonal jointing and bedding:

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This is one of many sites I visited Saturday near Bolt, West Virginia, on a field trip with NAGT’s Eastern Section.

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15 May 2015

Friday fold: Crumpled Carboniferous cyclothems

Twitter follower Bob J. submitted this week’s Friday fold: Carboniferous cyclothems at Scremerston, Northumberland.

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Thanks Bob!

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