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Messages 261 - 280 of total 300 in this topic << First  |  < Previous  |  Show All  |  Next >  |  Last >>
EdBannister

Mountain climber
13,000 feet
Feb 26, 2017 - 12:56pm PT
awesome post Dingus!!!!!!!
thebravecowboy

climber
The Good Places
Topic Author's Reply - Feb 27, 2017 - 08:22am PT
I've seen some washouts DMT and that is a gaper
EdBannister

Mountain climber
13,000 feet
Feb 27, 2017 - 10:37pm PT
Dingus, do you have a view that shows what looks like an escarpment, is linear?
thebravecowboy

climber
The Good Places
Topic Author's Reply - Mar 6, 2017 - 09:01pm PT


tuolumne_tradster

Trad climber
Leading Edge of North American Plate
Mar 6, 2017 - 09:40pm PT
My conclusion... our little scarp is the result of mudslide and subsequent erosion by Del Puerto Creek. :)

DMT: looks like terracette landforms on that hillslope ^^^...not sure if they contributed to the landslide.
Wikipedia...
In geomorphology, a terracette is a type of landform, a ridge on a hillside ... formed by soil creep or erosion of surface soils exacerbated by the trampling of livestock such as sheep or cattle. Synonyms (not preferred) are: catstep, cattle terracing, sheep or cattle track.

Example of terracettes near Morgan Hill, CA
tuolumne_tradster

Trad climber
Leading Edge of North American Plate
Mar 6, 2017 - 10:20pm PT
That's the San Joaquin / Orestrimba thrust fault, which marks the boundary between the central valley and Diablo Range / coast range geologic province. That's an ancient fault line associated with subduction and its corollary to the north, the Stony Creek Thrust, mark where the Franciscan zone subducted beneath the edge of N America, back in the day.

DMT: I think the Stony Creek Thrust would be equivalent to the Tesla-Ortigalita fault on this geologic map of the Del Puerto Canyon area, not the San Joaquin fault. Note that the SCT and the T-O faults juxtapose Great Valley Sequence against Franciscan Complex.


The San Joaquin / Orestrimba fault is the boundary fault between the Diablo Range/Coast Range and the Great Valley physiographic provinces.


FYI...
Tesla-Ortigalita Fault, Coast Range Thrust Fault, and Franciscan Metamorphism, Northeastern Diablo Range, California

Article in Geological Society of America Bulletin 84(11) ˇ January 1973
DOI: 10.1130/0016-7606(1973)842.0.CO;2


Fault contacts in the northeastern Diablo Range, California, between the partially mélanged late Mesozoic Franciscan Complex and the broadly coeval, less deformed sedimentary rocks of the Great Valley sequence have been called, by definition, the Tesla-Ortigalita fault. "Coast Range thrust" is the name applied by Bailey and others (1970a) to the fault of regional extent that originally separated subducted oceanic crust and sedimentary rock of the Franciscan Complex from structurally overlying ophiolite plus shelf-slope facies sedimentary rock of the Great Valley sequence. The two faults are not equivalent. High-angle Neogene segments of the Tesla-Ortigalita fault truncate older fault surfaces of the Coast Range thrust-fault system. Franciscan metamorphic rocks contain low-to high-pressure, low-temperature mineral parageneses characterized by the phases pumpellyite, prehnite, aragonite, lawsonite, glaucophane, and jadeitic pyroxene. Metamorphism has been variously ascribed to metastable re-crystallization, metasomatism by fluids generated in and around serpentinite, structural burial produced by subduction of an oceanic lithospheric plate, and burial plus tectonic overpressures generated beneath the Coast Range thrust fault. Suppe (1970) and Ernst (1971a) argued against metastable recrystallization and metasomatism on the basis of available field and laboratory evidence. If metamorphism is related to serpentinization, a metamorphic aureole should surround ultramafic bodies undergoing present-day ser-pentinization. Metamorphism resulting from tectonic overpressures generated beneath the Coast Range thrust fault will be revealed by an increase in metamorphic grade toward the thrust, whereas structural burial would result in an increase in metamorphic grade with structural depth. Distribution of mineral parageneses in the northeastern Diablo Range, revealed by analyses of more than 300 thin sections of metaclastic rocks, shows no spatial relation between highest grade rocks and either exposed segments of the Coast Range thrust fault or the margins of ultramafic masses undergoing present-day serpentinization. Thus the available evidence fails to support the metastable recrystallization, metasomatic, and tectonic overpressure concepts. Only the hypothesis of structural burial is not negated by the observed relations.
StahlBro

Trad climber
San Diego, CA
Mar 6, 2017 - 11:05pm PT
EdBannister

Mountain climber
13,000 feet
Mar 6, 2017 - 11:30pm PT
tradster, how about Gorman to Lebec
tuolumne_tradster

Trad climber
Leading Edge of North American Plate
Mar 7, 2017 - 08:47am PT
tradster, how about Gorman to Lebec

intersection of the Garlock & San Andreas faults?

tuolumne_tradster

Trad climber
Leading Edge of North American Plate
Mar 7, 2017 - 08:48am PT
Yes when you put those mountain cows on flat ground they just walk around in circles!

I think it is called the Cowriolis effect. On the Earth, a cow that moves along a north-south path, or longitudinal line, will undergo apparent deflection to the right in the Northern Hemisphere and to the left in the Southern Hemisphere. ;-)
tuolumne_tradster

Trad climber
Leading Edge of North American Plate
Mar 7, 2017 - 05:50pm PT

http://scedc.caltech.edu/Module/links/sensemap.html
StahlBro

Trad climber
San Diego, CA
Mar 8, 2017 - 10:00pm PT
tuolumne_tradster

Trad climber
Leading Edge of North American Plate
Mar 8, 2017 - 10:14pm PT
Franciscan knockers make good sea stacks.

Lots of downed trees on the Loop Trail, Armstrong Redwoods

Mini-hoodoos
jonnyrig

climber
Mar 13, 2017 - 10:53pm PT
Gnome Ofthe Diabase

climber
Out Of Bed
Mar 23, 2017 - 02:12pm PT
Haven't a clue if the brave cowboy needs iron?

This seems to be almost to good to be true ?

https://www.mountainproject.com/v/fs-full-nailing-rack---54-pins-17-heads--yosemite-bigwall-hammer/112573338

That's a pretty a a picture as any mouse poem, more useful too
thebravecowboy

climber
The Good Places
Topic Author's Reply - Mar 23, 2017 - 02:43pm PT
thanks gnome

StahlBro

Trad climber
San Diego, CA
Mar 23, 2017 - 05:57pm PT
tuolumne_tradster

Trad climber
Leading Edge of North American Plate
Mar 23, 2017 - 06:43pm PT
very nice serpentinite outcrop photos DMT...thanks for posting


The Melones Fault Zone (MFZ) is an important structure recognized in the Mother Lode district to the south, where it represents a major fracture of the foothills fault system of the western Sierra Nevada Mountains separating Mesozoic rocks to the west from Paleozoic rocks to the east. It is likely a conduit that tapped auriferous solutions at great depth during tectonic deformation in the geological past. Gold and silica (quartz) rose from these depths in the Mother Lode district as illustrated by some mines in the district that reached depths as great as 5,000 feet. It is likely that much of this gold was derived from the serpentinites of the MFZ.

http://californiangold.blogspot.com/2013/05/the-giant-king-gold-mine.html

Interesting video on gold-bearing quartz vein formation...
[Click to View YouTube Video]
tuolumne_tradster

Trad climber
Leading Edge of North American Plate
Mar 23, 2017 - 06:53pm PT
Serpentinite shear zone in the Coastal Belt Franciscan on Sonoma Coast near Jenner CA

Rock!...oopsie.

Trad climber
the pitch above you
Mar 23, 2017 - 07:31pm PT
Messages 261 - 280 of total 300 in this topic << First  |  < Previous  |  Show All  |  Next >  |  Last >>
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