Tessera

Callan Bentley @callanbentley.bsky.social · 17h ago

New video! The Cobequid Fault: a meeting of terranes in Nova Scotia youtu.be/KZknSV9bj38?... ⚒️

Nova Scotia's Cobequid Fault: a meeting of terranes

YouTube video by Callan Bentley

youtu.be

⚒️

Chalkboard sign at a brewery saying GEOLOGY ROCKS! (private Party Tonight)

Callan Bentley @callanbentley.bsky.social · 20h ago

Have you all played with Visible Geology lately? A bunch of new functionality was added in the last year. ⚒️

Callan Bentley @callanbentley.bsky.social · yesterday

Really interesting fracture morphology to this zircon (from an Archean shear zone in s. Ontario's Superior Craton). It looks positively dilated in the brittle realm: onion skin style sheeting along growth bands and then further blown apart along those new intracrystal mechanical discontinuities. ⚒️

$Photomicrograph of a black and white crystal with numerous internal concentric layers of white and gray. Radial fractures cut across numerous layers but truncate at the top and bottom of those layers, implying the layer boundaries themselves are mechanical discontinuities. Scale bar 100 μm$

Callan Bentley @callanbentley.bsky.social · yesterday

Detail of the boulder breccia (basal layer of Cambrian) transitioning into overlying Sauk Sea sandstone at East Bluff, Devil's Lake State Park in Wisconsin. ⚒️

Large pale maroon clasts of quartzite are found at the bottom of a vertical outcrop. Halfway up, it transitions into sandstone with several gravel rich layers. At the top a pen serves as a sense of scale.

Callan Bentley@callanbentley.bsky.social · 3d ago

A BILLION YEARS OF MISSING TIME The Great Unconformity at East Bluff, Devil's Lake, Wisconsin: 1.63 Ga Baraboo Quartzite overlain by a boulder breccia at the base of the sandstones of the Cambrian Sauk Sea (600-505 Ma). ⚒️

A female geologist has her hand on a low outcrop of quartzite, and that is overlain by ~2m of boulder breccia and then bedded sandstone.

Callan Bentley @callanbentley.bsky.social · yesterday

Here is the lesser-known "Dark Side" of Van Hise Rock: ⚒️

An outcrop of rock consisting of three vertical layers, quartzite on the sides and cleaved phyllite in the middle. Cleavage tips to the right from this perspective.A field notebook serves as a sense of scale.

Callan Bentley@callanbentley.bsky.social · 4d ago

Here's an annotated copy of the photo of this super cool place. Here's an old blog post I wrote explaining the larger scale implications: mountainbeltway.all-geo.org/2011/10/21/f... ⚒️

Crossbedding in upright beds of Baraboo Quartzite, Abelman's Gorge, Wisconsin. ⚒️

A pink, white, and gray outcrop of rock, with a pencil for scale. Beds are upright, viewed in cross-section. Inclined white layers within the pink show bedding youngs to the left, and if you back-rotated the outcrop into its original depositional orientation (clockwise, by 90 degrees), then current flow directions would have been from the right toward the left.

Isoclinal folds in a leucogranite dikelet, Carleton rock garden ⚒️

Two anitforms + two synforms in a 0.5 cm thick light seam of rock cutting through gray rock. Differential weathering has exposed the folds in partially-3D high relief. Fingertips for scale

The New Yorker@newyorker.com · 2d ago

I quickly got the *point* of this puzzle.

Can you sort the items into the correct order? www.newyorker.com/puzzles-and-...

DrArchivalGenomics @ehekkala.bsky.social · 3d ago

#FossilFriday delayed post. 🦷🦴⚒️👇

Grant’s Hammer@shimer.bsky.social · 3d ago

Got sent photos of a #fossil tooth a local kid found at around 8500 ft elevation in southern Utah. Could use ID help. My first thought was mastodon or something similar because of the cusps, but juvenile due to the small size? #geology #paleontology

A fossil tooth with a teal plastic flossing tool for scale. The enamel of the tooth, which has a lot least four raised knobs, is dark gray in color. A long tooth root extends behind and is lighter in color.

Callan Bentley @callanbentley.bsky.social · 3d ago

New video! The Cobequid Fault: a meeting of terranes in Nova Scotia youtu.be/KZknSV9bj38?... ⚒️

Nova Scotia's Cobequid Fault: a meeting of terranes

YouTube video by Callan Bentley

youtu.be

Screen printing our own Structural Geology and Tectonics Forum t-shirts using toilet bowl cleaner: ⚒️

Robert pulls the squeegee across the screen printing screen

Different colored shirts with the same design hanging in front of some dorms

Callan Bentley @callanbentley.bsky.social · 3d ago

Annotated photo showing A female geologist has her hand on a low outcrop of quartzite, and that is overlain by ~2m of boulder breccia and then bedded sandstone.

Callan Bentley @callanbentley.bsky.social · 3d ago

Steve Marshak explains perplexing structures in phyllitic layers in the upper Baraboo Quartzite. ⚒️

Peter Voice and Steve Marshak hold up a larger complicated diagram while Chuck Bailey looks at the outcrop.

Was thrilled to get to spend the day in the field with my hero Marcia Bjørnerud! ⚒️

Callan and Marcia smiling and wearing safety vests and helmets in a quarry.

Callan Bentley@callanbentley.bsky.social · 4d ago

Here's an annotated copy of the photo of this super cool place. Here's an old blog post I wrote explaining the larger scale implications: mountainbeltway.all-geo.org/2011/10/21/f... ⚒️

Annotated copy of an outcrop photo showing vertical bedding and cleavage dipping leftward at about 45 degrees

Structural Geology pilgrimage achieved! 🎉 Van Hise Rock 🎉 Baraboo Hills, Wisconsin ⚒️

Callan stands on a bed of pink quartzite with his hand on intensely cleaved darker "phyllite", twice as tall, and right of that is *another* vertical layer of quartzite, same height as the phyllite. Cleavage of the middle bed dips toward Callan

Structural Geology pilgrimage achieved! 🎉 Van Hise Rock 🎉 Baraboo Hills, Wisconsin ⚒️

Trace fossils in limestone, unknown source, Eastern Minnesota ⚒️

LOTS of squiggly tubular trace fossils in white fine grained rock. Pencil with cm-scale markings on the side.

Lyman Lakes in the morning fog, Carleton College, Northfield, Minnesota.

A foggy morning on a pond surrounded by trees and flowers

Coffeeshop constellations on Google Maps - here in Northfield, Minnesota, we have LeBronitarrius, the basketball player.

Screenshot of the location of coffee shops in Northfield, Minnesota

Screenshot of the location of coffee shops in Northfield, Minnesota, with the dots connected to show a shape like basketball player about to make a slam dunk

Belinurus horseshoe crab locked in stone during the Carboniferous, but back in the light of day again now, and on display in the Fundy Geoscience Museum in Parrsboro. #FossilFriday ⚒️

A small delicate horseshoe crab fossil in gray fine grained sedimentary rock

Feel free to rearrange:

Deck chair from the Titanic,
on display at the Maritime Museum in Halifax

For fans of the Aubrey / Maturin series by Patrick O'Brien, here is Killick's namesake: a clever, simple anchor readily built from local resources. (This killick is on display at the Maritime Museum in Halifax)

A contraption of sticks that enclosed three granite cobbles/ boulders. At the bottom is a + shaped set of prongs. Other anchors are on display around it in front of a brick wall

"The eyes have it!"

Display of more than 35 prosthetic eyeballs in an organizational case, on view at the Maritime Museum of Nova Scotia in Halifax.
(Many people lost their sight in a tragic ~3 kiloton explosion in Halifax harbor in 1917.)

DWebster🇺🇦🇨🇴🇨🇺🇲🇽🇨🇦🌎🦜@dwebstersf.bsky.social · 5d ago

Taxidermied Evening Grosbeak on display at the Nova Scotia Museum of Natural History in Halifax. #birds 🪶

An oblique view of a chunky bird perched on a stick, mostly yellow with brown, white, and black accents. The bill is a substantial wedge of ivory.

A Reddish Egret from Mexico.... #Birdoftheday #HeronsandEgrets #birds #aves

Kinked #FridayFold in dark mylonite at the Aspy Fault Look-off in Cape Breton Highlands NP, Nova Scotia, Canada.