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Messages 81 - 100 of total 104 in this topic << First  |  < Previous  |  Show All  |  Next >  |  Last >>
Fritz

Social climber
Choss Creek, ID
Mar 15, 2019 - 09:03am PT
Thanks folks for the "geologists-speak" posts. It's good for me. An "old" climbing partner of mine has spent his career as a "hard-rock" geologist, mostly based out of Fairbanks.

Rumor has it, he is retiring to about 80 miles away from me this spring. He is not a loquacious fellow, but is an avid hiker. Hopefully I can lure him to some old mountain mining areas of interest to me.

photo not found
Missing photo ID#555269
Oplopanax

Mountain climber
The Deep Woods
Mar 15, 2019 - 12:21pm PT
rocks are nice but geomorphology is nicer.

[Click to View Linked Image]

[Click to View Linked Image]

[Click to View Linked Image]
Contractor

Boulder climber
CA
Mar 15, 2019 - 01:44pm PT
Again, I'm geologically illiterate so some knowledgeable feedback would be great.

The back country of the Peninsular Ranges have become my vacation home- specifically the Eastern most sections of the ranges from North to South. The abundance of Marble, Quartzite, Schist and other sedimentary rock that has beed baked into the Granite makes for great juggy boulders and some very interesting lines on the bigger faces. It seems the further East you go the more variable the granite becomes. I'd assume this is because of the inland seas that once existed there.
Credit: Contractor
Credit: Contractor
Contractor

Boulder climber
CA
Mar 15, 2019 - 02:33pm PT
Credit: Contractor
One more.
Minerals

Social climber
The Deli
Mar 17, 2019 - 06:10pm PT

It seems the further East you go the more variable the granite becomes.

Variable in what way? The surface texture and size/shape of the climbing holds, or the actual granitic rock type, mineral composition, and rock texture? Or do you mean the amount of older metamorphic rock (xenoliths) that are hosted within the granite/granitic rock?

I am not familiar with western SoKal geography. I found your landslide deposit on Google Earth, but am curious as to the location of your most recent photos.
Contractor

Boulder climber
CA
Mar 17, 2019 - 06:56pm PT
Hot Springs Mountain, Sants Rosa Mountain and the Eastern boundaries of San Jacinto. This is where I've encountered layers quartzsite within the granite as well as other rock that I can't accurately Identify. These areas are very close to ancient inland sea beds; Palm Desert, Borrego, La Quinta are all just a few feet above sea level.

I mostly climb Mt. Woodson and other areas around San Diego. The granite here seems to have almost no layering of other rock. Disclaimer- I build houses better than I do geology. I also like to find good rocks!
Minerals

Social climber
The Deli
Mar 17, 2019 - 09:57pm PT

Ok, thanks, Contractor.

This is where I've encountered layers quartzsite within the granite as well as other rock that I can't accurately Identify. These areas are very close to ancient inland sea beds...

If I understand your question correctly, I think you are asking if you can correlate the sedimentary material (“inland sea beds”) that you see around the Salton Sea area, with the layered rocks that are hosted within the granites (granite, granodiorite, tonalite, etc.).

Although the rocks may have a very similar ‘sedimentary’ layered appearance, they are different rock types, and are of very different ages. I don’t know the geology of that area specifically, but with a quick online search, it looks like the seds around the Salton Sea are on the order of just a few million years old at most, while the granitic rocks are Mesozoic – mostly Cretaceous (~66-145 million years ago (Ma)). See the geologic time scale link below for more specifics. It also appears that there are Paleozoic (~252-541 Ma) metasedimentary rocks in the area, which are probably the “marble, quartzite, and schist” that you refer to above, that you see within and around the granite. These metamorphic rocks are much older than the granite, and were already there when mamga intruded into the crust, and then cooled to form the granite. The bits of metamorphic rock that have broken away from the main metamorphic masses and are hosted within the granite are referred to as xenoliths (i.e. your last photo of the boulder). Metamorphic xenoliths should not be confused with mafic enclaves, which are blobs of dark-grey diorite (etc.) that formed at roughly the same time as the granite, and may be genetically related to the host granite.

There are probably quite a few different granitic units in the area, of varying age and rock type; each different batch of magma of a given composition, texture, and age is referred to as a pluton. For example, all of the granitic rock in the Sierra Nevada is made up of many different plutons, the whole of which is referred to as a batholith (i.e. Sierra Nevada Batholith). Also keep in mind that the San Andreas Fault and associated faults have displaced everything to the west (of the faults) towards the north, so the metamorphic and granitic rocks in your bouldering area formed at a geographic location to the south of their present location (relative to the North American Plate).


https://www.geosociety.org/documents/gsa/timescale/timescl.pdf


Here is a bit of geologic info on the area. Although the web page focuses mainly on tectonics and faults, the first geologic map (Figure 1) may be helpful:
https://pages.uoregon.edu/rdorsey/CoachellaValley.html
(One thing that is also interesting is that in the upper left of Figure 4, “760-ka Bishop Ash” is listed. This is from Long Valley Caldera on the east side of the Sierra, from the same eruption that produced the Bishop Tuff – Owens River Gorge climbing. That’s cool.)


Wiki:
https://en.wikipedia.org/wiki/Salton_Sea


And for a generalized overview...

Interactive basic geologic map of California:
http://maps.conservation.ca.gov/cgs/gmc/
Found here:
https://www.americangeosciences.org/critical-issues/maps/california-geological-map


And a book that might interest you, if you are motivated to learn more:
https://www.amazon.com/Roadside-Geology-Southern-California-Sylvester/dp/0878426531


There’s always more info to find online too.

Contractor

Boulder climber
CA
Mar 18, 2019 - 06:24am PT
Excellent Minerals- Thank you!

The link below was particularly helpful in identifying, specifically the Late Cretaceous Mylonite concentrations in the Santa Rosa. The map legend showed this rock specifically where I've come across it.
https://pages.uoregon.edu/rdorsey/CoachellaValley.html

The formations are striking
Credit: Contractor
...but more importantly, for my purposes, it makes for great bouldering
Credit: Contractor
Oplopanax

Mountain climber
The Deep Woods
Mar 18, 2019 - 01:19pm PT
I wouldn't be surprised if what you call "layered quartzite within the granite" is actually an aplite dike.
Mandobob

Trad climber
CO
Mar 18, 2019 - 01:59pm PT
Contractor

"Again, I'm geologically illiterate so some knowledgeable feedback would be great.

The abundance of Marble, Quartzite, Schist and other sedimentary rock that has beed baked into the Granite makes for great..."

I could be mistaken but I believe the metamorphic rocks you are describing are much older than the Jurassic Age (?) granitic rocks which intruded these existing rocks. There may be some contact metamorphism with some of the sedimentary rocks that these granitic rocks intruded into (skarns)that might be characterized as being "baked" by the granite.

Source: Geology of California (Norris & Webb), John Wiley and Sons, 1976.
Nick Danger

Ice climber
Arvada, CO
Mar 18, 2019 - 02:07pm PT
Contractor, really nice photo of bouldering on that granite outcrop.
I an rather a fan of your photos.
cheers
Nick
tuolumne_tradster

Trad climber
Leading Edge of North American Plate
Mar 18, 2019 - 03:03pm PT
A conceptual model of the granitoid rocks in the southern Sierra Nevada by Cal Tech's Jason Salleby...

[Click to View Linked Image]

https://www.researchgate.net/scientific-contributions/20486150_Jason_B_Saleeby
Contractor

Boulder climber
CA
Mar 18, 2019 - 03:34pm PT
Nick, thank you!

Whatever this rock is, its hard and fine grained. There seems to be a wicking effect as well, so no chalk needed. You can crank on this stuff.

A fascinating Native American and Natural history exists here that ties into the geological activity . There's fossils of animals that existed in the Caribbean at one time- this, I believe links into the age of the sedimentary rock.

There's also Native American, stone fish traps that can be found high on the hillsides above the Coachella Valley. These are remnants of a massive lake formed in recent centuries by shifts in the flow of the Colorado River.

Love this thread!
originalpmac

Mountain climber
Timbers of Fennario
Mar 18, 2019 - 06:14pm PT
I know that loose flake! As per the link gstock posted on the first page of this thread: It mentions a 20'x30' flake still attached with rubble behind it. I am 98% positive that I tiptoed across that flake in 2016. We were moving slow, party of three and ended up climbing through the night. When the sun rose we were nearing the top of the chimneys and decided to bail. Couldn't reverse the traverse on rappel and had to pick our way straight down through the rock scar, leaving gear anchors. I remember feeling that if the 3 of us jumped in unison we could have dislodged that scary mother. Interesting to see it in print, that it is know to be precarious. Although it WAS frighteningly obvious.
Thread drift and I apologize. Good luck to the OP in his search for work in his field. I have personally reached out to ST for advice on career ideas and have received valuable insight. As such I am working on becoming a lineman. Just got a class A CFL learners permit. First step!
tuolumne_tradster

Trad climber
Leading Edge of North American Plate
Mar 18, 2019 - 07:22pm PT
DMT: time to consider a periodontist...LOL
Brandon-

climber
The Granite State.
Mar 19, 2019 - 07:25am PT
Most of this thread is way over my head, but if I could re-choose a career it would be geology. I love rocks, probably why I got into climbing. Wyorockmans joke is lost on me. But, this photo is super cool. Very dynamic. Love it.

Credit: Brandon-
tuolumne_tradster

Trad climber
Leading Edge of North American Plate
Mar 19, 2019 - 09:04am PT
[Click to View Linked Image]

Pinto gneiss...
[Click to View Linked Image]

Reference
Miller, W.J., 1938, Pre-Cambrian and associated rocks near Twenty-nine Palms, California: Geological Society of America Bulletin, v. 49, p. 417-446.

Aplite dike in monzogranite...
[Click to View Linked Image]

Reference
ftp://ftp.consrv.ca.gov/pub/dmg/pubs/cg/1998/51_05.pdf
Contractor

Boulder climber
CA
Mar 19, 2019 - 10:22am PT
Anyone here ever climb Sundance at Suicide to the Sundike finish (3rd pitch)? The second pitch has you moving up this beautiful face via xenolith horns with fun mantles to a blank 12 foot traverse- I thumb press on a tiny xenolith at my waist then 25 feet of 5.6 with no pro to the anchor. Next, veer left and alternate side-pulls up the 1" wide marble dike- its too steep to pull straight up! Classic climb relative to this discussion.
The dike- Photo cred to Mountain Project.
The dike- Photo cred to Mountain Project.
Credit: Contractor

The xenoliths on the steeper part of Dome Rock come to mind as well.
300 foot rope solo
300 foot rope solo
Credit: Contractor
This dike laden line was an Erik Eriksson 10d-X route. I was a drooling coward so I dropped a 300 foot TR solo line.
tuolumne_tradster

Trad climber
Leading Edge of North American Plate
Mar 19, 2019 - 02:29pm PT
Mafic xenolith chikenheads in granite, Phantom Spires
[Click to View Linked Image]
Contractor

Boulder climber
CA
Mar 19, 2019 - 03:00pm PT
Now that's beautiful!
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