Southern California Geology | Gabbro & Pegmatitic Dikes 

I grew up hiking these hills and still live in the area. You gave the best explanation I have heard on the composition of minerals.

That site brought back some memories. Paraglider pilots use that hill just up from where you parked your Jeep as a launch site we call Winchester Bowl. There is somewhat of a weed clearing about halfway up the hill where we would launch and fly for hours, then land down by your Jeep. I do remember finding shorl on that hill, and there were also largish books of mica. That last outcrop you dug around in looked familiar! There is also shorl over in the San Gorgonio Pass near Cabazon, but it is now hard to find specimens. I found a couple of pieces last year, but unless heavy rains wash away the surface, it hides from sight!

Had to come watch again, to share copy with a young friend interested in rocks. You are such a fun teacher, Todd. After living in Coachella Valley for 23 years, it is fascinating to finally learn about the terranes I traveled through so often. Many thanks for your videos.

The king has returned! Great vid, we've been missing you. Your excitement for geology is contagious

What a fantastic episode! I wish I was bit younger so that I could explore more easily. This complex is just a short drive from where I live and I'm looking forward to learning more about the geology of S. California. I've always wanted to learn more about identifying Gabbro. Thank you for taking time from your very busy schedule to bring us along with you on your explorations.

Thanks for the geology lesson(finally lol)in an area of SoCal I have been driving through or around for 60 years.

Wow! Great presentation. Only about 15 miles from my house. I'm going to go check that out very soon. Thank you.

I love your enthusiasm for the geology of Southern California. Thanks for doing this.

Super video, watching from Pembs UK, a very varied geological region.

Cool! I truly appreciate your enthusiasm and Jeff Corwinesque presentation style. We travel a lot, and I buy Roadside Geology books to read and narrate the geology we drive through. Found your channel and diggin’ it big time! Thanks again!

Plant and lichen notes: 4:17 _Encelia farinosa_ (brittlebush) white plant in background, also lots at 14:16. 6:15 _Acarospora socialis_ - green lichen on rock, also lots at 8:06. 8:45 _Xanthoparmelia cumberlandia_ - white lichen on rocks, and lots at 15:04. 10:24 _Salvia mellifera_ (black sage) at left. 13:03 _Eriogonum fasciculatum_ (CA buckwheat) - at center.

Fantastic video!

Great Video!

Great video, and right in my backyard too! I appreciate your enthusiasm about what you find and for sharing your knowledge about the local geology.

great episode, educational

Oh, yes, here we go again! Fascinating, interesting, cool rocks... and it's a place to hike to. I love that you included a paper, too. Thank you for taking us along, it's helpful to see through your eyes. Garnets! Is schorl more usually used to describe tourmaline? I've been to that area pre-geology; who knew such crazy diversity was just waiting there! Wow! (🎶🎶👌🏼)

Love those rocks

Thanks for the new video. Love it!

those were some huge hornblende crystals! Amazing. and then the beautiful schorl after in the pegmatite! Very nice!

What? You were gone for a minute? Just kidding. Missed you and great to see you’re back. …and front…and… Well you get it. Hope Santa Rosa Plateau and/or Tenaja Falls are among your future places to visit. Thanks for this video. Happy Christmas and Merry New Year!

Wonderful wonderful!I that final pegmatite with schorl and garnets was fascinating. Makes me want to check it out! Hope you have posted your spot or area at least to look!! Love you enthusiasm and sharing of knowledge.

Dude, unless I’ve missed some notifications, where the heck have you been?!. I really kinda started getting into your channel and then you disappeared all of a sudden. I’m in Northern California, Vacaville to be exact and so wish I was closer to your area of exploration. But I love your travels and videos nonetheless. I see everything ( the minerals) in this video at the Rock Shop in Vacaville, you’re ever in the area stop by the Rock Shop and explore that place, so much fun in there.. Anyway, so happy you’re back!! Sal

Good to see you back on RU-vid!

I’m still requesting you to do Teneja Falls. The falls have a great diverse rock formations.

Todd, ur back! Greeeat! Merry Christmas!

Some of the best geology stuff on the whole internet. Merry Christmas from Germany.

I think shawn wilsey also visited that tourmaline site.

Wonderful video! Thank you so much. I hope you continue to film in 2024. Happy new year!

As a botanist, people are always humored when I casually use the word "botanize". But it's a common and long-used word. Didn't know the geologists did the same grammatically!

Gnarly-a new Geologically Speaking video! You gotta love it! Thank you, Todd!

Nice to know that garnets are in the area. I have drove past that hillside many times.

Very interesting - thanks for making this. Those gabbros are excellent.

❤❤❤ great video! Interesting to tag along!! Thank you!

@ninainorway Yes THANK YOU, amazing what you found for us there, i loved it so much! I must look through all the pieces in my collection to see if I can find some gabbro! Or bits of pegmatites that contain schorl ! Your enthusiasm and finds and your fabulous way of explaining are a Christmas gift ! Thanks! Happy Holiday!

The garnets are interesting. They usually indicate metamorphism at a depth of at least 10 miles. Don't know if that is the case here. Great video BTW.

Thanks for your educational video and the hike up the hill. I'm beginning to think my specimen of Gabbro may be something else. Much for me to learn. 9 like .......

Thanks, always love these videos, and many times magmatic petrology is more interesting than it seems to be... Merry christmas!

Great video, thanks for pointing out the different kind of rocks and taking the time to observe. I love learning things from 😊your videos.

Green Acres is the place to be...

Thank you so much. An extraordinary outcrop of rocks!

If you bring along one of those 8 1/2 x 12 inch plastic wafer fresnel lens - then you can magnify the rock structure to the viewers - and give a greater clarity to what is being talked about.

great video, awesome gabbro!

Excellent Todd!

Good videos. Keep up the good work. In many of your videos (including this one) you refer to a book with some geologic maps of the area. What is the title and author of the book?

Wow, that's great. Here in Germany we very rarely have such large crystals.

Thank you for a great video. I am moving to the area and am looking forward to exploring. I was wondering what book you have those geologic maps in?

When you say "cools slowly" what does that mean? Is slowly one year, ten years, 100, 1000? How long does it take a quarts crystal to form? Enjoying your talks.

You described pegmatite as a crystal size term of over 1 cm. You showed hornblend crystals over that size but did not describe them as pegmatitic. Now I learned that there could be mafic pegmatites but those you showed were silicic as pegmatites commonly are. These I suspect were late stage injection of a differentiated magma that was enriched in silica?? That is an interesting process in its' own right. Gabbro and silicious pegmatite seem as incompatible as basalt and rhyolite. But those exist in proximity in Iceland in certain areas for particular reasons. There is a lot going on in a magma body deep underground.

Hi Todd, thanks for the video! Gorgeous gabbros! At 4:27 the chart you show seems to have the amphiboles and pyroxenes mixed up?? I'm pretty sure pyroxenes are more mafic than amphiboles. Just looked up another similar chart in google and it was different from this one. Curious! :)

The hill you are on is known locally as Mean Green. You are not very far from the old Hemet Magnesite Mine and the andalusite/corundum pegmatite.

Whoa, how long have you been taking a cosmic voyage .... ?

TIL that mafic is a portmanteau of magnesium and ferrous (iron).

Are the hornblend dikes actually all the way through the rocks or are some just on the surface as if it flowed over the rock? Your videos are awesome! Very passionate!

first off, thank you for these great videos. As a non geology professional but with an interest, I really enjoy and appreciate them and others. I have a question, why is there a difference in color between gabbro and basalt. basalt being very dark, I would think as it cooled slowly, there would be still be more dark area with the feldspar and other lighter crystals becoming more visible but still remaining less prominent than the darker ones?

PS do you lead field trips for the public??? Some of want to keep learning after college…

for me, it would make it more enjoyable, for those of us who live by here, to not give away the locations of such finds , they will now be striped and trash left behind, we have so many locations out this way, roc hounds know where to look, just my 2 cents been around these hills along time and seen the scale of the intrusion of more people, just dont give away exact locations,, love the roc formation info, it is addictive

Where can I get the map book you show in the videos?

23:08 Uh ... phrasing?