Tuesday, March 22, 2016

Death Valley Trip, Getting There: A Hike to Pleistocene Shorelines

On the second day of our road trip (which began here), we left Yerington at a reasonable though not early hour, knowing full well we'd make Beatty by dinner time.

About an hour later, after reaching the Alt-95–95 junction near Schurz and while still approaching Walker Lake, we found an opportunity to stretch our legs and see some geology in the process. We pulled into a side road leading to a gravel pit...and noticed a dirt road heading straight for some terraces, which I think are either tufa-cemented Lake Lahontan shorelines or a fault scarp.
These are some relatively low hills along the range front in the northern Wassuk Range.
But then we found the old highway, which was built above a historic highstand of Walker Lake—one that must have been at about 4060 feet, below Walker Lake's historic highstand that occurred in 1868 and was between 4089 and 4108 feet—and we left the gravel pit, driving north and looking for a dirt road to take us to the range front.
Here we're looking NNE along the old highway, toward some brightly colored, possibly hydrothermally altered rocks in the northern Wassuk Range.
Oh yeah, I'm a sucker for old roads!

We found a dirt road, one heading toward the canyon way to the left (below). Our goal? The Lake Lahontan shorelines and apparent Lake Lahontan high strandline on the rounded hill near the left.
We're looking southwesterly toward the range front.
A zoomed view of what look like shorelines. One range-front fault may be at the base of the slopes at the bottom of the photo. It's unclear to me from Google Earth how faults and shorelines are interacting.
The same range front and shorelines, looking more to the northwest.
Hike, hike, hike...hike, hike, hike. After about 15 minutes, I arrived at a boulder-strewn shoulder just below what I think is the highest Pleistocene shoreline.
We're looking west toward Reese River Canyon (not the same Reese River as in central Nevada). The canyon looks worthy of future explorations.
Now I'm standing on, as near as I can tell, the highest Lake Lahontan shoreline, looking to the south.
What's that across the dry wash?
Zoomed in, we can see a contact: poorly sorted Quaternary deposits above orange-brown hydrothermally altered rocks.
Is that a fault? Is it a sedimentary contact, either related to fan material being deposited along the range front or a wave-planed shore? I can't answer that question without going back to investigate.
MOH went on ahead to the top of the hill.
The highest ancient shoreline (Sehoo age) looked to me to be at the flat area I was standing on, just about at the often reported elevation of 1332 m (4370 feet), although the next slight break in slope—the change in color just below MOH—coincides with a strandline reported elsewhere of 1338-39 m (about 4390-4393 feet).
Looking to the north, we can see this same break in slope (the one I was standing on), with some ancient shorelines below it (especially to the far right). Note the change in color—green above to yellow below.
The yellowish or straw-colored areas along the break in slope are from a closely spaced, dried-out plant, probably Halogeton.
Done with my brief shoreline study, I walk back down to the bouldery shoulder, thinking that I'll eventually examine the intriguing contact across the wash.
First, I'm distracted by the granitic boulders. This one has a nice pegmatite dike cutting across, weathering out in relief.
Then I'm distracted by these little wildflowers growing on, near, and all around the granite boulders.
This is some kind of filaree or storksbill, probably Erodium cicutarium.
A lizard!
A bee!
Perhaps I got carried away (and didn't get to the contact across the wash) because this was the first wildflower spot of the trip.
The bouldery slope seen from below.
I turned my sights to the east, to the western range front of the Gillis Range, where I could see more ancient Lahontan shorelines.
This part of the Gillis Range is called the Agai Pah Hills.
Back at the Jeep, I looked off to the northeast, to a broad, flat area really out in the middle of nowhere.
I decided to test out my 300mm zoom (450mm in 35mm equivalent). The closer, rocky hills don't have a place name on USGS maps. Red Ridge is the name of the lower hills beyond that; the mountains beyond are the Sand Springs Range, south of Fairview Peak.
We continued on our way, southward toward Hawthorne, Mina, Coaldale, Tonopah, and Beatty.

Location map

Related Posts (in order of posting):
Death Valley, "Super" Blooms, Turtlebacks, and Detachments
Death Valley Trip, Part 2: More of the Badwater Turtleback Fault
Death Valley Trip, Part 3: Northward, and over Daylight Pass
Death Valley Trip, Getting There: Wave Clouds beyond the Sierra

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