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You are browsing the archive for faults Archives - Mountain Beltway.

16 August 2018

A suite of deformational features in Lancaster limestones

In the Landisville Quarry, Lancaster, Pennsylvania, there is a quarry that cuts into Cambrian limestones. (The exact identity of these limestones is apparently a matter of some dispute, but that’s not going to stop us!) I visited the quarry in June on a field trip offered through the NAGT’s Eastern Section annual meeting. We witnessed multiple varieties of deformation there. First off, there was straight-up brittle extension, resulting in bedding-perpendicular …

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10 April 2018

An outcrop showcasing a strand of the Kentucky River Fault System

Roadcuts in Kentucky show Ordovician limestones of two distinct types, replete with fossils and primary sedimentary structures, and juxtaposed by a fault, one strand in the Kentucky River Fault System.

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23 March 2018

Friday fold: Snow day edition

Snow may have cancelled the geology class, but there’s plenty to see outside! Join us for a tour of three fine examples of physical analogues in snow that show deformation akin to that we observe in rocks under tectonic stresses.

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23 January 2018

A kid and his slicks

On a family hike, Callan’s son finds some interesting smooth lines on a rock. What are they? What do they tell us? Tune in for a brief history of Appalachian geology.

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30 December 2017

Normal faulting in the San Felipe Volcanic Field, New Mexico

A glance out the airplane window over New Mexico triggers a bit of web research and a new view of tectonic extension via Google Earth and geologic maps.

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22 December 2017

The #FaultCup semifinals

Over the past few weeks, there’s been a fun game playing out on Twitter, hosted by Jorge (@lithospheric), called The Fault Cup, or #FaultCup in Twitterspeak. There’s a bracket showing one-on-one match ups between different faults, and then a 24 hour Twitter poll is posted, where the audience can vote for which one they want to advance to the next round.  Click through to embiggen. If you’ve missed the fast …

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5 December 2017

The quarry in Contessa Gorge

Central Apennine stratigraphy and structure is on display in the wall of a quarry in Contessa Gorge, Italy. Have a look a nice normal fault and a submarine mass transport deposit.

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29 September 2017

Friday folds: soft sediment deformation in thin sections of MTD sandstone

The Friday folds are small soft-sediment deformational features within a dismembered, folded sandstone (a “ploudin”) from a mass transport deposit from the latest Devonian of West Virginia.

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11 August 2017

Friday fold: Eagle Rock

For the Friday fold, Callan digs out images of Eagle Rock, Virginia, well aged in his digital archive for a decade!

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7 February 2017

Basaltic strata, faulting, and glaciation in western Iceland

Today, let’s journey to Iceland, to a bit northwest of Reykjavík. This is a view from the top of the Grábrók cinder cone, across the valley to the east. With very few exceptions, Iceland is a big pile of basalt, and that shows through in the walls of this valley, which display a stack of basaltic lava flows, intercalated in places with pyroclastic debris or volcaniclastic sediment. One portion of …

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