Callan Bentley

This was Gray whale Cove. Point Reyes tomorrow...

A student explains transpression to a group of other students atop the tower atop Mount Diablo

A group of students stand on top of a weathered sandstone outcrop

Fossil scallops in sandstone

Our main destination today was Mt. Diablo, a transpressional pop-up that gives an astounding view over the whole region. We saw Yosemite and the Golden Gate in one panorama! We also explored Great Valley Group sediments for fossils! ⚒️

An older man in a baseball cap and flannel shirt talks to students

Greenish gray conglomerate, fingers for scale

View of the opposite side of the road, showing reddish weathering basalt on top of greenish gray sedimentary strata

Volcanologist Steve Self joined our crew today at a great road cut east of the Caldecott Tunnel showing Miocene conglomerates in contact with Coast Ranges Volcanics basalts. ⚒️

A round pebble.that looks like an egg has a crack in it.

A new baby outcrop is getting ready to hatch! ⚒️

Squinting students in front of very tightly folded turbidites

I suppose, but these rocks have taken a long chaotic ride along the San Andreas Fault. There's all kinds of shenanigans that they've been exposed to along the way. Check out the super tight folding behind these students for instance. ⚒️

Okay, I'm listening. What criteria are you looking at that make you think it was back rotated?

Tilted high contrast sedimentary rock layers displaced along a central crumbly zone, top downhill to the left

Tilted high contrast sedimentary rock layers displaced along a central crumbly zone, top downhill to the left, annotated with arrows

Lovely low angle normal fault in Devil's Slide turbidites. ⚒️

A sunny beach with mountainous headland in background and students walking toward tantalizing outcrops

Just another day in the office. ⚒️

Gently dipping layers of graywacke and black shale

Gently dipping layers of graywacke and black shale, annotated to show younging direction

Finally got to see the legendary upside down turbidites at Devil's Slide. Spectacular rocks! ⚒️

Students and professors discuss a beach side outcrop of granite

Granite with dozens of vertically oriented MMEs, cut by a diagonal vein of epidote

Katryn Wiese of the College of San Mateo joined us for the granites of the Salinian Block today at Gray Whale Cove Beach. ⚒️

Green anemones

Chiton

Sea creatures

The bathtub syncline at Fitzgerald Marine reserve, near Moss Beach, California

😊

⚒️

That's beautiful

Feel free to suggest some phrasing

Boulder of stretched-pebble metaconglomerate with horizontal foliation along which pebbles are boudinaged.

A loose boulder of the Camp Reynolds metaconglomerate lying on the beach. ⚒️

Gray pebble in tan matrix, broken into at least five pieces along fractured that dip toward the photographer at ~45°, with white vein material seen between the segments.

Gray pebble in brown matrix, broken into at least nine pieces along fractures orthogonal to the pebble's vertical long axis, with white vein material seen between the segments.

Another couple examples of photogenic accordioned pebbles: ⚒️

Photo showing a tan metaconglomerate that shows chunky pebbles at left and more vertically smeared out flakes of pebbles at center right. Hand for scale

Here's a pretty spectacular strain gradient in the metaconglomerate: less deformed at left, grading into highly strained (smeared out) at right: ⚒️

Photo of a close up of a strongly vertically foliated rock with elongated pebbles that have been broken into chunks. Fingertips for scale.

Annotated photo of a close up of a strongly vertically foliated rock with elongated pebbles that have been broken into chunks. Fingertips for scale. One pebble has been outlined and interpretive arrows showing the rock being compressed from the sides and elongating vertically are shown.

Visited one of my favorite stretched-pebble metaconglomerates yesterday at Camp Reynolds on Angel Island. Spectacular boudinage of individual pebbles to extraordinary dimensions. ⚒️

Five members of the PVCC Geology Club show off the geology pins on the back of their t-shirts

We have a whole suite...

A medium-sized gray-brown canid with yellow eyes and big ears and an open mouth

Coyote, Angel Island, CA.

A hummingbird on a twig flaring out its METALLIC FUSCHIA THROAT WINGDINGS

Anna's Hummingbird, Angel Island, CA. #birds 🦉

Western Grebe (left) and Clark's Grebe (right), San Francisco Bay

Western Grebe (left) and Clark's Grebe (right), San Francisco Bay #birds 🦉

A group of students perched on serpentinite looks Westward toward the Golden Gate Bridge

Looking at the Golden Gate Bridge from Angel Island. ⚒️

California poppies growing in front of serpentinite with strongly developed scaly fabric

... And here's the state flower with the state rock: ⚒️

Orange flowers in green grass

California poppies on Angel Island.

Students examine an outcrop with oceanic surf in the background

Tafoni holes in seaside graywacke.

Examining tafoni at Baker's Beach. ⚒️

Alan Pitts talks about Italian seismogenic normal faults in front of the oblique slip Corona Heights MEGASLICKENSIDE

Yep, the very very best

Yes

A very, very, very very very very very very very very very, very polished fault surface reflects the blue sky

The insane, mirror-like shine of the Corona Heights Fault. ⚒️

Marshall's Beach