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[caption id="attachment_608" align="aligncenter" width="610"] Brecciated marble in Mosaic Canyon, Death Valley[/caption] Mosaic Canyon, in Death Valley National Park has some beautiful mylonitized marble. Here that marble has been brecciated into fragments by a fault. [caption id="attachment_614" align="aligncenter" width="610"] Christie Rowe shows us how be the fault is.[/caption]

[caption id="attachment_605" align="aligncenter" width="610"] Pseudotachylyte injection in the Homestake Shear Zone, Colorado[/caption] Fault pseudotachylyte is formed during an earthquake. The coseismic slip on the fault frictionally heats the surrounding rock and forms a melt. Rapid cooling of the melt forms a glass-like, dark rock, pseudotachylyte. A combination of the dynamic stresses imparted on the wall rock during the earthquake and dynamic pressurization will allow the melt to enter fractures in the wall rock. In the photo above pseudotachylyte is the thin, black rock. The injection is at a 90 degree angle with the main pseudotachylyte vein.

Well the year is winding down so I thought I would give a little recap of some highlights. Jess and I are planning our winter Southwest roadtrip I think I'll have to let her drive a bit. It might get dangerous with me at the wheel. Are you taking a holiday road trip? Don't forget to bright a geologist.  Remember to be the more accurate, it might be necessary to decelerate: I was conducting what has been called x-mph geology, where x is the miles per hour one is driving; this time I was doing 70-mph geology. Geology at seventy miles per hour (or 70-mph geology) is generally much less detailed and often less accurate than geology at 20 miles per hour (20-mph geology). And it turns out that if you slow down to about 5 mph or less, you can almost complete a rock report on whatever iron-stained jasperoid or copper-stained porphyry you happen to be driving by, and the speed is almost slow enough for the geo-type in the passenger side of the truck to lean out and grab a sample. Are yo...

[caption id="attachment_595" align="aligncenter" width="610"] Soft sediment deformation at Point Lobos, California[/caption] This weeks photo comes from a spectacular outcrop at Point Lobos, California. If you are there, try to time it with low tide, or you'll miss this. Soft sediment deformation occurs in unlithified sediments. Sometimes a trigger such as rapid loading by a mass wasting event or an earthquake is necessary to cause the deformation.   Flame structures (middle right in the photo) form when the overlying sediment (orange) is denser than the underlying sediment (black). This causes the overlying sediment to sink down into the low sediment, which pushes the lower sediment up. The structures formed resemble flames, hence the name. Also in the photo (near the pointing finger) is a more competent sediment that was normal faulted as the unlithified sediment below it deformed. What other structures do you see in the photo? Here's another sh...

I'd packed up all my gear. Ryan had a phone interview at 11, so I said goodbyes to the rafting adventure crew we'd shared the cook shelter with and walked down the bike path to the Squamish Adventure Center for some coffee. When Ryan rocked up, we piled into his Tacoma and drove for Vancouver. The rain had finally shut down climbing at Squamish. We rolled into Van famished. Ryan knew a sushi spot, so I yelped it and we made our way there. It was a sushi factory . The place was hustling and turning over. We sat down, I didn't have much time to oogle at the amazing sushi prices before we ordered. Then bam, the sushi was before us and we gorged. I'd never been so full on sushi for so cheap before. As I forced the last bite of raw salmon into my mouth, the bills slammed down on our table. We paid and were kicked out the door to free our table for the next set of mouths. When I flew into BC a month before, I'd only briefly been in Vancouver. Really just long enough to ge...

I had to dig this one deep out of my archives, so sorry for the poor image quality. [caption id="attachment_579" align="aligncenter" width="720"] Folded chert in the Marin Headlands[/caption] This is a roadcut in the Marin Headlands, North of San Francisco California. Chert is made of microcrystalline quartz from radiolaria, microscopic protozoa with silicate skeletons. When radiolaria die their skeletons sink to the bottom of the ocean floor. After compaction and diagenesis, chert is made. The chert in the Marin Headlands is part of an accretionary wedge block and is folded into chevron folds. Don't forget to follow Upsection on Instagram to see more rocks! Do you have pictures of a cool outcrop? Submit them to FridayRocks@upsection.com Wahrhaftig, Clyde. "Structure of the Marin Headlands block, California: A progress report." (1984): 31-50.

This weekend only I'm offering handcarved leather dog collars at a discount for the holidays. Get your best friend something they'll love for christmas. All collars are treated with neatsfoot oil or mink oil to protect against water. I have a limited number of materials so first come first serve. Send me your dog's neck size (remember two fingers should be able to comfortably fit under the collar), dog's name, and color preference. Email me at timothyjsherry@upsection.com for more details. Feel free to leave questions in the comments section. I'll answer them here.

Check out this great two part episode of Star Talk Radio where Neil deGrasse Tyson interviews science journalist Miles O'Brien (PBS News Hour) about CNN firing its science reporting staff and the future of science reporting. Also featured on the episode is Bill Nye the Science Guy and Elise Andrew (I F***ing Love Science) weighing in on points made by Miles. It's an eye opening interview on the business of network news and how science doesn't fit into the picture. Find Part 1 here and Part 2 here .