Friday fold: An odd duck
A USGS colleague shows Callan a bizarre fold outcrop in the Conococheague limestone of the Boyce quadrangle, Virginia.
cleavage
Friday fold: Up on Opequon Creek
I got a call last month from Rebekah Wiedower, a landowner up in Frederick & Clarke counties (her family’s property includes pieces of both), inviting me to come up and look at some anticlines and synclines that Dan Doctor (USGS) had identified on the bank of Opequon Creek. I was glad to do it, though … Read more
Rock Cycle I: Sedimentary → Metamorphic
An outcrop of the Ordovician-aged Martinsburg Formation is used to illustrate the development of slaty cleavage, and hence a major transition in the Rock Cycle.
Friday fold: Natural Bridge area, Yoho National Park
The Friday fold, delayed by a week from last week’s contest, appears in Yoho National Park, British Columbia, near the “Natural Bridge” over the Kicking Horse River.
Friday fold: lower Martinsburg Formation near Bixler’s Ferry
The Friday fold is presented in photo, annotated photo, and GigaPan formats. It’s a cleaved anticline in lower Martinsburg Formation limy slate from Page County, Virginia. See if you can spot Mr. E. coli in the GigaPan!
Structures seen at Floe Lake
A showcase of geologic structures observed between downpours of rain at Floe Lake, Kootenay National Park, British Columbia. Cleavage, bedding, folds, faults, and strain are all presented for the discerning structural reader’s edification and titillation.
Veiled geology at Naked Creek
As I mentioned, Monday had me out in the field, looking at the western Blue Ridge and eastern Valley & Ridge provinces in Virginia. This was a field review for the new geologic map of the Elkton East quadrangle by Chelsea Jenkins, Chuck Bailey, Mary Cox, and Grace Dawson. Immediately after lunch, we visited an … Read more
Overturned bedding in the Weverton (?) Formation
On Monday, I was out in the field at the Blue Ridge / Valley & Ridge transition (“boundary”?) in the Elkton East quadrangle, where Chuck Bailey and students (from the College of William & Mary) were leading a field review of their new geologic map. A field review is a form of field-based peer review, … Read more
Veins perpendicular to foliation
To recap the week so far here on Mountain Beltway: On Monday we looked at some sweet vertical boudinage along the plane of tectonic cleavage (not to mention those folds in a (formerly) horizontal granite dike, now bearing vertical axial planes), and then on Tuesday we looked at a horizontal cut through that same outcrop, … Read more
Exquisite boudinage in Ontario
Callan shares images of extraordinary boudinage outcrops in strained Archean meta-basalts on the Quetico-Wabigoon subprovince boundary within the southern Superior Craton. Ogle these gorgeous structures in awe and wonder.