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

31 March 2012

Slick!

Slick!

Slickenlines (fault grooves) and fault polish on a chunk of sandstone in far western Texas.

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30 March 2012

Friday fold: ice in Iceland

Friday fold: ice in Iceland

Searching for Peter Luffi’s latest Where On Google Earth? challenge, I found myself touring Iceland last week. While I didn’t find the strange comet-shaped feature he posted, I did find this: And zooming in a bit, to the high-contrast area in the center: This appears to be volcanic ash layers distorted by glacial flow and then melting/sublimation/weathering/erosion/ablation of the glacier. I posted something similar as the Friday fold almost a …

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29 March 2012

New year’s atop Lion’s Head

New year's atop Lion's Head

My first view of Lion’s Head, the little butte northwest of Table Mountain, came through the fog on the morning that Evelyn and Jackie took Lily and I to Sea Point to see the migmatite: A lofty pinnacle – made of the same flat-lying quartz sandstone as the mesa of Table Mountain to the southeast: We went back to Lion’s Head on New Year’s Eve. After a delicious Thai dinner, …

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28 March 2012

Hanksite and other wonders of Searles Lake

Hanksite and other wonders of Searles Lake

Callan’s field studies class journeys to Searles Lake, California, a playa rich in evaporite minerals both prosaic and exotic.

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27 March 2012

Tafoni weathering of Malmesbury Group turbidites

Tafoni weathering of Malmesbury Group turbidites

Some tafoni (pattern of little weathering pits) expressed on Malmesbury Group (~700 Ma) turbidite sandstones at a little outcrop on the eastern shore of False Bay, South Africa: That last one seems to have some concentric layering to the tafoni pits – exfoliation? Spheroidal weathering? Hmm…

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26 March 2012

Malmesbury Group sediments on the eastern side of False Bay

Malmesbury Group sediments on the eastern side of False Bay

In December, Callan found an outcrop of Neoproterozoic-aged turbidites in South Africa, on the eastern shore of False Bay.

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23 March 2012

Friday fold: a tortured tempestite

Friday fold: a tortured tempestite

Hand sample of folded limestone strata in West Virginia (presumably Devonian in age). Note the rip-up clasts and large grain size at the base of the sample (to the right in the photo). Note the fine-grained, thin-bedded shale laminations towards the top (left) of the sample, too. Together, they tell a story of decreasing energy in the environment of deposition: maybe an ancient storm deposit (a “tempestite,” one of the …

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22 March 2012

Plane views

Plane views

Here are some photos out the window of my flight home from California the week before last… Snow on the north sides of mountains, but not on the south sides (view is from the south towards the north): Same thing here: And again… And again… it would appear that our route from Reno to Minneapolis had us routed over the northern hemisphere! Variation on the same theme: light-colored sand deposits …

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21 March 2012

More folds from the White Mountains

More folds from the White Mountains

I know we spent time last Friday on some nice folds in the Poleta (?) Formation in the White Mountains of California, but here are a few more that I saw on my way up to the Ancient Bristlecone Pine Forest… Some elliptical objects caught my eye: Traced out along the plane of bedding, these turned out to be boudins of a more competent layer, which was tightly folded higher …

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20 March 2012

Eruption column in Owens Valley :)

Eruption column in Owens Valley :)

I’ve been showing a lot of photos lately from my field course’s trip up into the White Mountains. While we were driving up the road from Westgard Pass to the Ancient Bristlecone Pine Forest, we saw something interesting going on in the southern Owens Valley. Take a look at this view to the southwest, from the overlook: See it, way there in the distance, but between the photographer’s vantage point …

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