Vicky VeritasDec 20, 2022

Slickensides

Slickensides form on rocks in fault planes as the rocks scrape past each other. They are polished surfaces with parallel (to fault motion) striations or grooves called slickenlines. This can happen suddenly during an earthquake, or gradually during creep.

Below are some slick (and famous) slickensides with mirror surfaces from San Francisco. More detail on these slickensides from Callan Bentley’s great AGU blog, Mountain Beltway: https://blogs.agu.org/mountainbeltway/2015/12/28/corona-heights-fault-san-francisco/

Bonus: See a collection of slickensides and more information from our own Andrew Alden @alden https://www.thoughtco.com/gallery-of-slickensides-4122857

#slickensides #slickenlines #EarthQuakeFaults #rocks #geology #ScienceMastodon @geology

Corona Heights Fault, San Francisco

At the end of the AGU Fall meeting, Callan visits the Corona Heights "mirror" fault, renowned for its gorgeous slickensides. Explore the site in photos in GigaPans.

Mountain Beltway
Show threadJessTheGeologistDec 21, 2022
@vickyveritas what a beautiful fault! 🤩
Show threadVicky VeritasDec 21, 2022
@DrRocktagon Tis! Thank you!
Show threadTim N7KOMDec 21, 2022

@vickyveritas @DrRocktagon last week I uploaded an old video of that fault, the Corona Heights Faults, to my YouTube channel. I think this is circa 2011 maybe 2012... That's @keepitrheol giving everyone the lowdown.

https://youtu.be/ApczXVI_h7g

Corona Heights Fault Slickensides | San Francisco Geology

YouTube
Show threadChristie RoweDec 23, 2022
@tsherrygeo @vickyveritas @DrRocktagon I just want to point out that Jamie and I still have those jackets. Anyone want to Fault Party @ Corona Heights around AGU in 2024?
Show threadTim Dawson
@keepitrheol @tsherrygeo @vickyveritas @DrRocktagon We totally need a AGU Corona Heights fault party in 2024. Maybe AGU should sponser and rent out the Randall Museum as event space.
Dec 23, 2022 at 5:46amWeb
Show threadChristie RoweDec 31, 2022
@timblor @tsherrygeo @vickyveritas @DrRocktagon Past years we just wander down to get some margaritas around Market and Castro which is a great way to find out whether people feel like they know what they saw or not!! I've definitely failed as a guide a few times, before I realized that some people imagine faults only in cross section with an offset marker. Seeing a messy anastomosing set of slickensides in a volume of messy breccias and no clear offset markers doesn't always click.