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You are browsing the archive for January 2012 - Mountain Beltway.

31 January 2012

Crisp limestone syncline

Nice straight-limbed syncline in the Helderberg Group of West Virginia (Devonian limestones, mainly): Alan Pitts shot a sweet GigaPan of this outcrop which you can explore here, or you can just look at this zoomed-in detail: Aaron Barth is down there in the lower right corner for scale.

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30 January 2012

Brallier cross-beds

More evidence of currents in the Devonian deep… Primary structures that give us clues, preserved in a place where preservation over 360 million years isn’t necessarily guaranteed. As you might expect, this turbidity currents roared in from the east, where the mountains were rising, and generating a fair bit of sand and mud, during the Acadian Orogeny. (The view in this photo is looking towards the south.)

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29 January 2012

Tofu with hackle fringe

We were making dinner last week and took out a block of “silken” tofu* with less care than we should have, and it broke. But what a break! The fracture showed a gorgeous elliptical joint face that broken up into a twisted series of hackles along its fringe: That’s something nice homogeneous fine-grained rocks do, too! I hereby challenge all my tofu-eating readership to attempt similar tofu-fracturing experiments, and to …

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28 January 2012

Two new bugs

Got access to the wife’s photos from South Africa. Here are two other charismatic insects:

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27 January 2012

Friday fold: Twisted turbidites

These are turbidites of the Malmsbury Group in South Africa, on the east shore of False Bay.  A couple of nice little folds running sub-vertically through the package… Happy Friday!

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26 January 2012

The mixed-up quartzites of Cape Agulhas

Callan and his wife journey to Africa’s southernmost point, and find a geological mystery there.

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25 January 2012

Berlin Falls, South Africa

Here’s where to find it, if you want to. Can’t say I recommend it – just an overlook, with no opportunities to hike or swim or explore in any more detail than just passively observing gravity exert its pull on water unencumbered by underlying rock.

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24 January 2012

Paleoproterozoic stromatolites from the Malmani Dolomite (Transvaal Supergroup)

After our safari, Lily and I were taken up onto the Great Escarpment in northern South Africa. The escarpment is supported by sedimentary strata of the Transvaal Supergroup that overlie the Archean basement rock of the Kaapvaal Craton. The Transvaal strata are Paleoproterozoic in age, somewhere between 2.5 and 2.0 billion years old. They are a mix of siliciclastic sediment and carbonates. Here’s the view from an overlook dubbed “God’s …

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23 January 2012

An ancient delta at the Three Rondawels?

Here’s a look at what you see if you go to the Three Rondawels viewpoint above the Blyde River Nature Reserve in northern South Africa: A lovely scene. The three mega-hoodoos on the left are the eponymous “rondawels” (pronounced ron-da-vulz), which is the Afrikaans word for a round hut. These erosional remnants are more or less cylindrical and of the same dimensional ratio as the huts, so this name seems …

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22 January 2012

Rheology of an overheated waterbottle (with stickers)

Last fall, when I was out backpacking in Dolly Sods, we left one of Lily’s water bottles on the dashboard of the locked (and windows-rolled-up) Subaru. When we got back to the car, we found it had experienced heterogeneous solid-state deformation. I took a few photos, so that those of you who are interested in rock deformation could ponder them as analogues for the contrasting styles of deformation we see …

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