Friday fold: Buckle vs. passive folding in the Chancellor Group slates
The Friday fold is an outcrop in Yoho National Park that showcases differences between buckle folding and passive folding.
foliation
Friday fold: New Market / Lincolnshire formation contact, Staunton, Virginia
Happy Friday! Here’s a view of the folded contact between the (older, lower) New Market Formation, and the (younger, upper) Lincolnshire Formation, as exposed in Staunton, Virginia: The contact has been folded, pretty intensely: The New Market Formation is massive, light-colored, and exhibits fenestral texture here. The Lincolnshire is darker, more thinly-bedded, and is chock … Read more
Kink bands in highly strained Laurel Formation, Rock Creek Shear Zone, DC
Last week before GSW, I spent several pollen-choked hours in Rock Creek Park, GigaPanning some of the rocks of the Rock Creek Shear Zone. Here are some exposures in the bed of Broad Branch that show lovely kink banding. In at least one spot, you can see a conjugate pair, so these rocks were (1) … Read more
“Outcrops” on the barn at Peirce Mill, DC
The Friday before last, I was in DC for a fun geology/botany field trip, and I got the opportunity to stroll around the barn at historic Peirce Mill, a historical grain mill along Rock Creek in Rock Creek Park, Washington, DC. The barn is immediately south of Tilden Street NW. It appears to have been … Read more
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
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.
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.
Blue Ridge Thrust Fault field trip
One of Callan’s former students leads a field trip to examine the western edge of the Blue Ridge geologic province, attempting to answer the question of whether the Blue Ridge / Valley & Ridge contact is indeed the trace of a thrust fault. Breccias and S-C fabrics tell part of the story…
Two new macro GigaPans
With my new “macrogigapan” rig from Four Chambers Studio, I produced these images last week as part of my Mid-Atlantic Geo-Image Collection project (M.A.G.I.C.). … Dive in! Porphyritic andesite from the Beartooth Plateau, Montana: [gigapan id=”96524″] Foliated limestone slate, location unknown: [gigapan id=”96977″] Clicking on the word “GigaPan” in the lower right corner will take … Read more