Chasing History - Death Valley - Spring 2016

Fantastic write up! I didn't realize there were so many historic signs out there.
It's been an excellent write up, easy to visualize from our visit there.
 
Bseek said:
I too was intrigued by the "wicking effect" comment. Not something I have ever heard about before, but it makes sense. How amazing to see it in action.
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We also saw the same effect at the lower Cottonwood spring. We walked up both mornings to confirm it was a daily event. Pretty cool stuff and one of the joys of being able to camp close. You never know what you'll see! :)
 
The hydrologists would call this "evapotraspiration-driven diurnal groundwater/streamflow fluctuation". Short version, as Ski aptly put it: the cottonwoods draw up so much water during the day, the spring stops flowing.

Must be amazing to see.

Hard for an Easterner to wrap his head around. We live on a sponge with a sometimes dry rind, sometimes perpetually wet. Apparently we have diurnal groundwater level variations here, too, but probably not on the same scale as in an arid, mostly sunny climate.

Foy
 
Foy said:
The hydrologists would call this "evapotraspiration-driven diurnal groundwater/streamflow fluctuation". Short version, as Ski aptly put it: the cottonwoods draw up so much water during the day, the spring stops flowing.

Must be amazing to see.

Hard for an Easterner to wrap his head around. We live on a sponge with a sometimes dry rind, sometimes perpetually wet. Apparently we have diurnal groundwater level variations here, too, but probably not on the same scale as in an arid, mostly sunny climate.

Foy
Click to expand...
Apologies for a hijack... Here in parts of Oregon, there's an effort to remove the juniper trees that have spread widely in the past 100 plus years. Like Cottonwood and Tamarisk, they are very thirsty and consume much of the groundwater and annual rainfall. In areas where the juniper has been taken out, we are seeing reports of dry streams now having year round flows.
 
I was never much of a bug or critter geologist, but those are some fine pictures of some fine bugs and critters,

Given the fact that DV is still very, very active in terms of regional tectonics, it would not surprise me in the least to learn that uplift causing dissection of older fanglomerates is going on. I love me some fanglomerates. We actually have some in the East, where early Cambrian fanglomerates mark the unconformity between the Precambrian basement and the Paleozoic sedimentary section along the western flank of the Blue Ridge Mountains, and here in the Piedmont where rift basins of Triassic/Jurassic age rapidly filled with sediment along the border faults of the half-grabens as the Atlantic Ocean opened back up following the Alleghanian Orogeny. Within 10 miles of my Raleigh, NC home, the shoreline of Falls Lake exposes some terrific fanglomerates chockablock full of boulders of granites, gneisses, and metavolcanic rock eroded from the adjacent upthrown side of the Jonesville Fault.

I doubt that wind erosion is the root cause of the arcuate undersides of the boulders in the Alabama Hills, but it probably provided the finishing touches. Spheroidal weathering begins wirh a particular fracture pattern, called jointing, within masses of unweathered rock. The arcuate joints often seen in granites and similar crystalline rocks was long thought to have arisen from "unloading" as rock was removed from over the granite body by erosion and the granite reacted to removal of vertical stress by fracturing along curved planes mimicking the ground surfaces above. Other theories are now discussed in attempts to explain how the "onion-skin" joint pattern first develops.

Once the joint pattern does develop, groundwater gets to work and chemically weathers the granite minerals, chiefly the feldspars and the dark minerals including biotite mica and hornblende, which are rather more susceptible to chemical alteration than the quartz within a piece of granite. Chemical weathering alters the feldspars and dark minerals to clay in a process known as replacement, where clay minerals replace the biotite and other dark minerals, preserving the texture of the unweathered rock. The resulting in-place, texturally consistent material is known as saprolite and can be thought of as "rotten rock". Saprolite is typically soft enough to dig with a trowel or a spade. Here in the East, a whole lot of bedrock mapping is done by mapping saprolite, so pervasive is the chemical weathering by abundant groundwater.

Anyway, once the joints break up the mass of granite into large slabs with surfaces more or less following surface contours (ie arcuate surfaces), alteration to saprolite along the edges of the slabs takes place. As the partially rotten slabs come to the surface by removal of overlying rock, their arcuate bottoms remain in the downward-facing position. THEN wind erosion may remove the softer, rotten rind of saprolite, leaving a boulder with a rounded top and an arcuate bottom resting atop another boulder.

At least that's what one amateur geomorphologist thinks is going on.

Oh, and be sure to read the piece about the still-uplifting Ventura anticline in your new "Geology Underfoot". Uplift is occurring as we speak in the hills between Ventura and Ojai.

Great stuff once again, sir! Many thanks for sharing.

Foy
 
Ski, you are like an artist. Every brush stroke reveals something different and very special. Probably 99.9% of what I know about DV I have learned from all of the posts during the past month. The only thing I knew was that it was hot most of the year. Ha! Thanks for sharing such an amazing trip report. jd
 
Very cool. What a neat resource to have at your back door. Thanks for sharing your adventures. Great photos too.
 
I've only gotten through Part I so far, but I'm very jealous already. I missed the bloom due to an unexpected trip to New Mexico, but at least I get to see the bloom through your eyes.

I was glad to see the "Goat Meal" thing was explained earlier because I was just about to PM regarding it as I thought you either meant "good meal" or "goat meat" and the goat meat option didn't quite sound right...
 
Foy said:
I was never much of a bug or critter geologist, but those are some fine pictures of some fine bugs and critters,

Given the fact that DV is still very, very active in terms of regional tectonics, it would not surprise me in the least to learn that uplift causing dissection of older fanglomerates is going on. I love me some fanglomerates. We actually have some in the East, where early Cambrian fanglomerates mark the unconformity between the Precambrian basement and the Paleozoic sedimentary section along the western flank of the Blue Ridge Mountains, and here in the Piedmont where rift basins of Triassic/Jurassic age rapidly filled with sediment along the border faults of the half-grabens as the Atlantic Ocean opened back up following the Alleghanian Orogeny. Within 10 miles of my Raleigh, NC home, the shoreline of Falls Lake exposes some terrific fanglomerates chockablock full of boulders of granites, gneisses, and metavolcanic rock eroded from the adjacent upthrown side of the Jonesville Fault.

I doubt that wind erosion is the root cause of the arcuate undersides of the boulders in the Alabama Hills, but it probably provided the finishing touches. Spheroidal weathering begins wirh a particular fracture pattern, called jointing, within masses of unweathered rock. The arcuate joints often seen in granites and similar crystalline rocks was long thought to have arisen from "unloading" as rock was removed from over the granite body by erosion and the granite reacted to removal of vertical stress by fracturing along curved planes mimicking the ground surfaces above. Other theories are now discussed in attempts to explain how the "onion-skin" joint pattern first develops.

Once the joint pattern does develop, groundwater gets to work and chemically weathers the granite minerals, chiefly the feldspars and the dark minerals including biotite mica and hornblende, which are rather more susceptible to chemical alteration than the quartz within a piece of granite. Chemical weathering alters the feldspars and dark minerals to clay in a process known as replacement, where clay minerals replace the biotite and other dark minerals, preserving the texture of the unweathered rock. The resulting in-place, texturally consistent material is known as saprolite and can be thought of as "rotten rock". Saprolite is typically soft enough to dig with a trowel or a spade. Here in the East, a whole lot of bedrock mapping is done by mapping saprolite, so pervasive is the chemical weathering by abundant groundwater.

Anyway, once the joints break up the mass of granite into large slabs with surfaces more or less following surface contours (ie arcuate surfaces), alteration to saprolite along the edges of the slabs takes place. As the partially rotten slabs come to the surface by removal of overlying rock, their arcuate bottoms remain in the downward-facing position. THEN wind erosion may remove the softer, rotten rind of saprolite, leaving a boulder with a rounded top and an arcuate bottom resting atop another boulder.

At least that's what one amateur geomorphologist thinks is going on.

Oh, and be sure to read the piece about the still-uplifting Ventura anticline in your new "Geology Underfoot". Uplift is occurring as we speak in the hills between Ventura and Ojai.

Great stuff once again, sir! Many thanks for sharing.

Foy
Click to expand...
Great stuff once again, sir! I can hardly wait to get back out and do some more looking and poking about! But first I've got my reading assignment for tonight.
 
I finally had time to pour myself a nice cup of coffee and read about your latest adventure to Death Valley. As usual, your photos were extraordinary and your story so fun to read.

That was an awesome pic of the fighter jet tanking up in mid air.

Definitely looking forward to more of your TRs...

Sent from my SM-G900V using Wander The West mobile app
 
Ski, when I recently joined WTW your posts of DV truly inspired me. As an "Easterner" the mention of Death Valley conjures up a blazingly hot landscape devoid of anything worth exploring.
Through your posts and blog we recently decided to take a trip out West and spent a week exploring this land you obviously love.

We came back with a renewed respect of a land with more wonders than just about any place we had ever been. We are already talking about going back next spring and seeing more of the secrets that is Death Valley...

Thank you.
 
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