Geologists think that the diorite at Bodega Head (part of the Salinian Block) was transported by the San Andreas Fault some 300 miles. Music: Stick Figure
Man…I caught myself asking myself “I wish Nick Zentner would bring his show south for some CA geology “. Then the RU-vid algorithm directed me to you! Thanks for the great content!!
These are plutonic granitics of magma and volcanic origins. These same pluton formations show up the entire West Coast of American (Oregon Rocks, Gearhart, OR, Cape Disappointment, Ilwaco, WA ...) now jutting upwards out of the beach shorelines. All were formerly-located pluton extrusions from further south - that weathered away their softer outer rock matrix - and were pushed up to their current elevations some 3-4 miles in height from their origins. The fact that you are showing granites, granodiorite, diorite ... and pegmatite ... they were deep underground for the longest of origins, cooling time, and HUGE crystallization. That pegmatite K-spar (potassium sililcate feldspar) further intruded into this prior cooled and cracked-open dioritic formation. These intense intrusions of seams and dikes, with huge pegmatite crystals, shows that this southern portion of the Sierra Nevada batholith was undergoing massive changes deep in the earth the further you get toward the equator. Massive geological forces cracked fractures across the diorite, allowing the new intrusive pegmatite seams and dikes. That pegmatite had an even longer cooling down timeline and larger crystallization than the diorite. Then both diorite and pegmatite were again crushed and fractured into fault lines. Diorite and Pegmatite both with a Mohs 7 hardness (out of 10) shows that there were massive and intense tectonic and geological forces happening at many periods in its rock cycle. In the end, these forces ripped off a chunk of the Sierra Nevada batholith formation, and pushed it 300 miles to the north and west. What was the original land north of Bodega Bay (north of San Francisco) was pushed those same 300 miles further north and west into the Oregon Klamath-Siskiyou and Shasta/Lassen mountain range consisting of 5 super magma chambers. Land to the south fractured from the Sierra Nevadas to Los Angeles was pushed into this current Bodega Bay location.
Those rocks have a definite "old" weathered look to them sitting among the "new" sand. The contrast is remarkable compared to other parts of the coastline. Really cool. Thank you Todd.
What I miss most about California -- the geology, geography, and the climate -- all of which are as varied just in that one state as the entire continent. I have plenty of geology to study and experience up here in the PNW, but the eastern Sierra Nevada has always fascinated me and is still my favorite section of my native state.
All that overburden of sedimentary rocks and sand (shown in the photo) were also scraped off the ocean bottom, put atop the diorite and pegmatite, pushed up above the water line, and transported all the way from Los Angeles to Bodega Bay (Santa Rosa north of San Francisco).
Original Orange County geology is now 300 miles north at San Francisco ... while current Orange County geology is former Baja California ! Viva la geologica !!!
Another chunk of the Sierra batholith can be found on the northern tip of Point Reyes, also traveling many miles on the San Andreas. I took a long bike ride there years ago to check this out. Thanks Todd. As always great info and reggae.
Thanks, Todd! Another great video, you've got a keen eye to catch these different rock layers and explain clearly. Looks like it was a beautiful day in Bodega Bay.
Yes ! The many whole sections of (current) California shoreline have broken off from ancient western coast shoreline and mountain ranges back as far as 66 MYA (K-T boundary) of the Cretaceous asteroid and dinosaur extinction event. They have broken off of proto-California and Central America (i.e. Mexico). Earth-Moon-Sun gravitational and geological tidal forces acting on the equatorial asthenosphere magma and rocky surface lithosphere have inched them to the west and north into their ~300 miles NW location. Not bad for 0.024 inches (0.06096 centimeters)/year of snail-trail movement all this time. All these plutonic gold, silver, and copper seams of Oregon and California come from their original Mexican equatorial regions of volcanoes, plutonic magma, and massive geological forces.
How VERY interesting! We lived close by for many years and never knew🤯… Do you have any info on lake county CA? We have a little volcano here…mount konocti. Amazing rocks!
The sand I presume is weathering from the rock formation. About how large are the sand grains? They look larger then the grains on the east coast in places.
