Showing posts sorted by relevance for query West Gate. Sort by date Show all posts
Showing posts sorted by relevance for query West Gate. Sort by date Show all posts

Friday, February 6, 2009

Friday from the Road: West Gate

As mentioned briefly in a long-ago post, West Gate is the westernmost of three geographic notches that Highway 50 passes through near Middlegate Junction: West Gate, Middlegate, and Eastgate. The three notches can be seen on this MSRMaps topo map, although only Eastgate is labeled. West Gate is here, with Middlegate Junction called "Middlegate," Middlegate (the notch, not the junction or the station) is here on the edge of two or more maps (which gives MSRMaps fits sometimes, so I zoomed way in) and Eastgate is here (likewise with the MSRMaps bit). You can click over to air-photo view in MSRMaps anytime to avoid these map gaps.
through trees You can get to West Gate from either the west or the east on that famous Nevada road, Highway 50. From the east, it is rather unprepossessing, as seen above from just a little west of Middlegate (the gate or notch) and a little east of Middlegate Junction. West Gate is that barely visible drop off seen through the fallish tree in the center of the photo (November, 2008).
near m-gate As you approach a little closer to West Gate from the east, while coming closer and closer to Middlegate Junction, West Gate appears as a gap between two hills and as a drop into Stingaree Valley. This photo was taken in the spring after things had greened up a bit (May, 2008).
50 sign Even closer still - right at Middlegate Junction and the turnoff to Middlegate Station and Gabbs (sometimes pronounced Gaaa-aaa-aaabs, like a lamb baaaa-ing, and never "gobs" like in "goblin") - and West Gate still doesn't look like much, as seen above through the Highway 50 sign. The photo was taken in the spring before things had greened up (April, 2008).
into stingaree Okay, enough of West Gate from the east! What about West Gate from the west? Above, in the distance, beyond the brown Earthquake Fault sign near the black car, and across Stingaree Valley, you can see the notch called West Gate. In fact, if you know where to look, you can barely see Middlegate the notch, and beyond that, you can make out where Eastgate would be if the east part of the Clan Alpine Mountains wasn't in the way.
corner Ah, now we've crossed Stingaree Valley and are rapidly heading into the notch-gate called West Gate. It's just the gap between the hill in shadow on the right (south) and the hill not-in-shadow on the left (north). The snowy Desatoya Mountains can be seen clearly in the background.
west gate Now we're arriving quickly into West Gate, coming into the shadow cast by the late afternoon sun.
moon Oh my! Suddenly the entire notch is in shadow and the moon is up! That's the difference made by about one year, two months and one hour (from January, 2009 back to November, 2007 - and back again below). A little artistic license, we'll call it!
windmill And why, you're thinking, might you even want to go to West Gate? There are several reasons: 1) the road passes through it and otherwise you will have to go way out of your way to the south on U.S. Route 6 to get across Nevada, or way out of your way to the north on the sometimes boring I-80, 2) the West Gate windmill is at West Gate (surprise!), and 3) there might be a bit of geology...

Oh, that will have to wait for later.


A little more about the geography:
West Gate is a notch cut into the western splay of the Clan Alpine Mountains, Middlegate is cut into the eastern splay of the Clan Alpine Mountains, and Eastgate is cut in a mini-forerange of the Desatoya Mountains. Eastgate Wash heads above the notch at Eastgate in the Desatoya Mountains, where one main upstream branch is called Buffalo Creek and another is called Big Den Creek. All the washes and creeks that feed Eastgate Wash are shown as intermittent, but there is almost always water in the deeply incised creek bed at Eastgate. From Eastgate, Eastgate Wash makes it westward across Highway 50 and past The Shoe Tree, through Middlegate (the gate), and then is channeled along Highway 50 to West Gate, after being joined by Bench Creek, which comes south out of the Clan Alpine Mountains. From West Gate and to the west, the wash either joins or becomes Dixie Valley Wash, depending on what map one uses. Dixie Valley Wash bends northward and ends in the Humboldt Salt Marsh in Dixie Valley.

Eastgate Wash is often dry, anymore, near The Shoe Tree. It is often damp to running part of the way along Highway 50 between Middlegate the gate and West Gate. It is almost always dry when I stop at West Gate, which really isn't very often, so I don't have good year-round-eyeball water data. In the cool and wet late 1970's, the wash at West Gate was dry to damp to running. This water information, such that it is, should be considered anecdotal at best.

Thursday, September 2, 2010

A Highway 50 Series

I've been working on a Highway 50 roadside geology series for quite a long time, and have managed to get a few posts in every now and then, but have many more to go before I really consider it complete (could it ever be complete?). The entire Highway 50 Series as listed below includes posts that reference Highway 50, stories about or revolving around Highway 50, and roadside geology some distance off Highway 50 (but not too far). The part of 50 that I'm considering as "mine" right now is really the stretch that runs through Nevada, from Stateline, Nevada, at Lake Tahoe to the Utah state line near Baker, Nevada. The Loneliest Road in America is considered to run from Fernley to the Utah state line near Baker, NV. Fernley is on Alt 50, which leaves 50 at Silver Springs, goes north to Fernley and then east toward Fallon. It rejoins 50 some few miles west of Fallon (I'm not sure whether to include Alt 50 as part of this series). I often access Highway 50 by driving through the canyon of the Truckee River from Reno to Fernley on I-80, but I won't include any of that with the Highway 50 Series.

I'm going to go ahead and list some things I haven't yet posted about that I consider part of this series. I have an intent to post about these areas; when or whether I get to them remains to be seen. So, from west to east:
  1. Locations color coded plain black (and not bolded) - I don't have photos for posts (though I might link to a photo in another post not entirely about Highway 50).
  2. Locations color coded red - I have photos but haven't written a post .
  3. Locations coded blue have a link to an existing post.
Additionally, I've listed some general Highway 50 road trip posts at the end of the main list; these go from one area on the road to some other area on the road. Some of these could be consolidated into location specific roadside posts, but so far haven't been.

CA Border to Hazen
Death Valley Trip, Getting There: Wave Clouds beyond the Sierra

Hazen to Sand Springs:
Dipping beds near Hazen
Soda Lake maar
Old barite mill (or not, location in question)

Grimes Point archaeology - petroglyphs in basalt
Salt Wells

Dust and Deflation (Fernley to Hazen to Fourmile Flat to Middlegate Junction)
Dust Devil Links (Eightmile Flat and Fourmile Flat)
Huck Salt Mine
Pink Playa Phenomenon (Fourmile Flat)
Lake Lahontan shorelines near Sand Mountain (on 80, on 95)
Sand Mountain for Sand Dune Week
Four Years Ago: Spencer Hot Springs, Kingston Summit, to Fallon
Spencer Hot Springs, Then and Now (a bit o' history)
Two Years Ago Today: The Loneliest Phone
Dikes near Sand Springs
Sand Springs (photo)

Sand Springs to West Gate:
Frenchman (for now, see Fairview Peak, Nevada)
Fairview Peak (photo)
Where in the West - March (Fairview Peak)
Fairview Peak, Nevada
Friday Fault Photos #6 (Fairview Peak)
Friday Fault Photos: Fault Scarp at Fairview Peak, Nevada
Friday Fault Photo: Fairview Peak, NV, Fault Line
Chalk Mountain (photos)
Things You Find in the Field: Stingaree Valley
West Gate geology
Friday from the Road: West Gate
Friday from the Road: West Gate Windmill
Lizards of the Day: Blue Bellies (at West Gate Windmill)
Windmill Down! (West Gate)

West Gate to Eastgate (old Highway 50):
Middlegate Junction (one sign photo)
Friday from the Road: Middlegate Station, central Nevada
Views from Middlegate
Friday - Back from the Road (Middlegate Station)
Backroads: Ophir and Out (Middlegate Station)
Xmas Greetings from Nevada! (Middlegate Station)
Clan Alpine Mountains (photo)
Geology on the Road: Flow-Banded Rhyolite with Breccia (Clan Alpine Mountains)
Geology on the Road: Breccia with Flow-Banded Rhyolite
Geology off the Road: a bit of Tuff, Fossil Leaves, and EarthScope
RIP Middlegate Shoe Tree
Ash-flow tuff near The Shoe Tree

Old 50 Turnoff to Reese River Valley:
Desatoya Mountains (west side photos, photo)
Back from Alaska (hike to Cold Springs Pony Express Station - CSPES)
Recent Hike: Water in the Desert (another hike to CSPES)
Cold Springs Pony Express Station (there's more!!)
Desert Critters: Horned Lizards (Cold Springs area in the Desatoya Mountains)
Signs of Fire (Edwards Creek Valley)
New Pass Canyon western roadcuts
Friday Fault Photos #4 (New Pass Canyon)
Shoshone Mountains (photo)
Columnar jointing in tuff near Mt. Airy Summit
Flash Flood on Highway 50 (Mt. Airy Summit, Mt. Airy Mesa)
Flash flood, sheet wash deposits, and erosion from 2008, with tuff

Reese River Valley to Big Smoky Valley:
Reese River Ravens
Reese River Valley (looking south photo, looking west photo)
Toiyabe Range (photo, photo, photo)
Stokes Castle
Friday from the Road: Austin, NV (Reese River, Austin)
Geology on the Road: Austin, NV (powder cache door, quartz monzonite, dikes)
Things to do in Austin, NV
Austin: Is it Time to Leave Yet?
West to Southwest of Center: Beers and Roads and Folds and Things
Things You Find in the Field: Speed Traps
Geology on the Road: Highway 50 #2 (ash-flow tuff & granite, Austin Summit)
Geology on the Road: Highway 50 #1 (ash-flow tuff, Austin Summit)
Austin pass geology, granite, faults
Bob Scott Summit granite, contact
Field Trip Day 1: Getting There (flowers, Bob Scott Summit)

Big Smoky Valley to Hickison and Pete's Summits:
Big Smoky Valley (photo looking north)
A Saturday Drive (Big Smoky Valley)
A Road Trip to the Hot Springs (Spencer's Hot Springs)
A Soak at Spencer Hot Springs
Four Years Ago: Spencer Hot Springs, Kingston Summit, to Fallon
Spencer's Hot Springs (also mentioned here)
Linka Mine skarn
Memories: First Trip on Highway 50 (Pete's Summit, Lone Mountain, Cortez)
Pete's Summit petroglyphs, graptolites (mentioned here)

Big Smoky Valley Area and Monitor Valley
SW to SWxS of Center: West Northumberland Canyon
SWxS to SSW of Center: The West Northumberland Canyon Springs and Northumberland Pass
South by West of Center: Monitor Valley Salt Flat or Dry Lake
Backroads: Too Cold to Change a Flat, and other Considerations
South of Center: Potts Ranch Hot Springs
The Geographic Center

Hickison Summit to Lone Mountain:
Hickison Summit ash-flow tuff, faults, base surge?

Hickison Summit petroglyphs in ash-flow tuff
Gold mines near Gold Bar up the 3 Bar Road
Three Bar Ranch Road

Lone Mountain to Eureka:
Eureka! It's Lone Mountain!
Lone Mountain: Intro to Stratigraphy
Lone Mountain Stratigraphy in Brief
Tweeting the Eureka Quartzite
The Eureka Quartzite at Lone Mountain
Antelope Range (photo)
What Dust Hazard? (Roberts Creek Rd, Slough Creek, east side of Lone Mountain)
ENE of Center: Breccia at Devils Gate
Coarse-Grained Calcite in the Devils Gate Breccia
More about Devils Gate: limestone, horst, sill (?)
Speaking of Slag and Silver (Eureka)

Eureka to Newark Valley:
Eureka Summit hoodoos in poorly welded tuff
Eureka Pass contact of tuff against limestone?
A Fan Weekend - Nevada Style (alluvial fan in Newark Valley)
Three Years Ago Today: Newark Valley Geology at 70 Miles Per Hour
Pancake Summit (mentioned here)
Newark Valley (looking west photo)

Newark Valley to Ely:
Busy Days! (Ruth to Jakes Valley)
Geology on the Road: Ely Limestone Panorama (near Illipah Reservoir)
Springtime in the Egan Range (north of the Thirty Mile turnoff)
Garnet Hill
Friday Fault Photos (Keystone Junction, Ely Limestone, fault and folds)
Geology on the Road: Highway 50 #3 (Keystone Junction continued)
Today's Hike: Trees, Wildflowers, Stratigraphy, and Faults (stratigraphy near Ely)
The Lincoln Highway: Quotes and Links
Friday Field Photo: Cannonball Chert
Falling Rock (rock slide near Ely)
Pronunciation... (Ely)
Signs of Spring: Ravens (Squaw Peak quartzite)
Tweeting the Eureka Quartzite (Squaw Peak photo)
The Eureka Quartzite on Squaw Peak


Ely to the Utah border:
Two Years Ago: Trips to the Ovens (Ward Ovens)
Cave Lake
A Change in Weather: Fall becomes Winter? (Duck Creek Range, Success Summit, mylonite, contact)
Success Summit view
TheTail(s) of Thirty or Forty Antelope (Steptoe Valley)
Geology on the Road: Slate near Connors Pass, Highway 50
Friday Field Finds: An Old Trommel (Spring Valley)
Snake Range detachment fault (mentioned, photo, photo, photo, photo, and header photo above)
Friday Fault Photos #9 (Snake Range detachment)

On and near Wheeler Peak:
Alpenglow and Tentglow
Hiking in the Mountains
Where in the West: Wheeler Peak
Our Campsite on Wheeler Peak
Bristlecone Pines
My First Geology Tool
Rock Glacier: The First View
Rock Glacier: Closer and Closer
Rock Glacier: Higher and Higher
Rock Glacier: Near the Top
Rock Glacier: View from Above!
Rock Glacier: History and Links
Friday Field Photos: Wheeler Peak
A Snowshoe Trip
More Snowshoeing
Wheeler Peak Photo Sets, Spring and Summer 2006-2009
Friday Field Photos: Tarn It! (Teresa and Stella Lakes)
Friday Field Photos: Looking down on some Alluvial Fans
The Trail to 10,800 Feet
The Trail to 11,600 Feet
The Trail to 12,100 feet
The Trail to 12,350 feet (Or so)
Plants and Birds and Rocks and Things: Another Trip to Wheeler Peak
A Quick Note (Teresa Lake)

General Highway 50 Road Trip posts:
Spring Snow Squall in Central Nevada (Middlegate to Mt. Airy Summit)
Back Again - At Least for Now (Clan Alpine Mountains, Shoshone Mountains)
This is (More or Less) a Test (Eureka to Fourmile Flat)
Friday from the Road: There & Back Again (Edwards Creek Valley, Big Smoky Valley, Antelope Valley)
Through the Rain (Clouds: eastern and central Nevada, West Gate, and beyond Reno)

Also see: Highway 50 Links; posts tagged Highway 50

Last updated 17Jun2016.

Friday, February 27, 2009

Friday from the Road: West Gate Windmill

It's been a few weeks since I left you on the road, arriving at West Gate, that notch in the mountains just a little bit west of Middlegate Station, so I thought I'd better get back to you, so you won't feel stranded.
part The main thing about West Gate, besides the notch cut conveniently through the Clan Alpine Mountains so Highway 50 could pass through, is the windmill.
all A full view of the windmill, as seen from behind a fence and gate, looking northwest.
top The top of the windmill, the part that spins round and round whenever the wind blows - which it does quite often.
pump The bottom part of the windmill: the center rod moves up and down, pumping water out of the ground.
ice A little water leaks around the bottom, freezing into ice in winter.
gate The water goes by metal pipe along the ground and then upward into this water tank built of rocks and concrete. The pipe can barely be seen behind the large fence post, near the top of the squarish water tank.
climb Now, being the good investigative sorts that we are, we'll climb the rock wall and peer into the tank.
water Water! In the desert! This windmill used to run most of the time, but it seems to have been off for a while in some recent years. In summer, a nice water tank full of water can be a great thing to find out in the middle of nowhere - especially after a hot day of field work - although I'd hesitate climbing in this one because it's right along the highway.

I crudely calculated that I've passed through West Gate at least 200 times during the past 3 decades. I'm wondering if it's more than that - the number seems low to me, but maybe not! There was some hope of me keeping track of the actual number had I tried counting sometime in the 1980's, but it's too late now for more than just a crude estimate.

And right about when this posts, I'll be passing through again, on the first leg of another journey to Alaska. We'll be at the Iditarod when it starts up (did I mention that yet?) - see countdown widget on the sidebar, right above an Anchorage temperature indicator. Posting may be light to non-existent, although I have some pre-posts ready to go.

Friday, July 31, 2009

Lizards of the Day: Blue Bellies

On a recent roadtrip through Nevada, on our way to a Geobloggers-in-the-Pub meeting, MOH and I stopped at the West Gate windmill. Lo and behold, after squeezing through the closed gate and walking around to the windmill side of the rock-and-concrete water tank, we saw a couple blue-belly lizards scurrying around on the shady north wall of the approximately six-foot-high water tank.
In fact, we saw two pairs of lizards, possibly mating pairs judging by how closely they stuck to each other. The first pair is in the first photo, the second pair in the second photo.
The first pair had a larger, darker-looking lizard and a slightly smaller, browner-looking lizard; similar coloring and sizing in the second pair was not quite as obvious. This is the larger, darker lizard of the first pair.
In this close up, we can vaguely see the bluish patch under the lizard's chin, and we can see a bit of the blue belly, along the side of the lizard between it's foreleg and hind leg.
This is the slightly smaller, browner lizard of the first pair, hiding between a water pipe and the north wall. Some of its spots are turquoise in color.
And here, he/she has run to the top of the rock wall, and we can see the under-chin and belly patches quite clearly. The blue to bluish turquoise patches on the bellies of these lizards consist of two side patches.
This is one of the lizards of the second pair. The fairly common or typical yellow coloring behind or under both sets of legs can be seen, especially the yellow behind the forelegs.
These lizards, commonly known as blue bellies, blue-bellied lizards, swifts, or Western Fence Lizards, are formally known as Sceloporus occidentalis. The subspecies seen here is called the Great Basin Fence Lizard, or Sceloporus occidentalis longipes. All S. occidentalis lizards are good to have around, as they may help keep ticks free of Lyme disease.

The location of West Gate on this MSRMaps map is marked by the windmill symbol. For more about West Gate read Friday from the Road: West Gate. This post is being submitted to Carnival of the Arid #6, hosted by Chris Clarke at Coyote Crossing.

Tuesday, July 25, 2017

High Water Across the West: Not at West Gate!

I was surprised when driving through central Nevada back in early May that things didn't really look all that green or wet, at least as compared to what I'd already seen in northern Nevada along the Truckee River, at Rye Patch Dam and the Humboldt Sink, at the Pitt-Taylor Reservoir and in Winnemucca, in Carlin Canyon, and at Honey Lake. Still, I expected Eastgate Wash to be running, because it does so often, at least in my memory. I didn't have a chance to check the wash out at Eastgate, where I expect it was running, but here it is at West Gate...dry on May 3rd.
At least the nearby West Gate windmill was pumping, so there was plenty of water for any blue bellies that might happen by.

Wednesday, June 4, 2008

Dust and Deflation

It started out as an average, desert day in Fernley - a bit windy, but average.By the time we reached Hazen, things were looking just a little dusty, and flags were standing completely sideways, the wind from the west.

Here we are in Fallon, MOH and I, getting ready to cross the desert to the east. I'm in the Prius, he's on the motorcycle, taking it out to our little house in eastern Nevada. We'll now have two high-mileage vehicles to drive, except when I take my 4WD to work

MOH, ahead of me, swings into the turn just beyond Grimes Point. We will now traverse the entire length of Salt Wells Basin, which includes Eightmile Flat and Fourmile Flat, two usually dry playas, formerly part of Pleistocene Lake Lahontan.

Map from MSR Maps, courtesy of the USGS. North is up; the large squares are townships - six miles on each side when surveyed perfectly, which - as you can see - they aren't.


The Salt Wells Basin is undergoing a bit of a dust storm, with dust blowing off the mostly dry playas across the road, this time from the south. Deflation is a term often used for this kind of wind erosion, when wind removes the loose, fine-grained material - in this case the dust and fine sand of the playa - and carries it away, directly into our path!

As we approach Sand Mountain - shown as "Sand dunes" north of Highway 50 on the above topo map - the blowing sand has completely enveloped what is often a large RV city on the east flank of the dune (right side of the photo).


And then we pass straight into the path of the dust and fine sand as it crosses the road just before the turnoff to Sand Mountain.

Ah, but the trip isn't over: we've now gone over Sand Springs Pass, and will cross LaBou Flat in Fairview Valley. Thermal updrafts below the overhead cumulus clouds are drawing dust off the valley floor, but not causing the rotation that creates true dust devils.



The above three photos show the dust in Fairview Valley, the first two looking to the east, the third looking southward from about the center of the valley, near the old site of Frenchman. Finally, we have crossed Fairview Valley, have crossed Stingaree Valley, and are entering the notch in the western part of the Clan Alpine Mountains, which is called West Gate.

As we arrive at Middlegate Junction - an old stage station between West Gate and Middlegate, the first two of three geographic notches that old Highway 50 passes through - we see that dust is still blowing. [The current path of Highway 50 makes it through only West Gate and Middlegate, missing Eastgate by a short few miles.]

More on Dust

Wind and Deserts

Monday, February 6, 2012

ENE of Center: Breccia at Devils Gate

About 35 miles east-northeast of The Geographic Center of Nevada, both Highway 50 and Slough Creek go through a gap in the south end of Whistler Mountain, a gap or notch known as Devils Gate.

Note: Devils Gates are scattered all over Nevada, including a second Eureka County Devils Gate located north of Eureka, west of the paved road between Eureka and Carlin. Our Devils Gate, the one in this post, is located about ten miles east of Lone Mountain and seven miles northwest of Eureka (MSRMaps location).
Coming into Devils Gate from the west just before sundown.

A large breccia can be seen high on the carbonate cliffs north of Highway 50 when you approach the gate from the west. MOH and I first noticed this breccia several months back; we pulled over to check it out with binocs, then mosied on, filing the place away for a future hike. Finally, coming back from Serbian Christmas, the time was right.

We pulled off the highway onto a little dirt entryway that accesses the old highway south of the main road, parked the truck, and started walking. By the way, we've had the Prius on this old road, so presumably the pullout is suitable for most vehicles. After making it across the highway, we walked down a rabbit-brush infested two-track road, crossed Slough Creek, and then bypassed a fence by walking over to its abutment against the cliff face.
As we skirted around the base of the cliff toward our goal higher in the cliffs, we made a discovery: we found a lower breccia associated with small caves and solution cavities. In the photo above, the upper, larger breccia is in a smallish, bright white patch in the far, upper left part of the cliff; the lower, smaller breccia is clearly visible in the lower right of the photo, closer to Slough Creek.
This labeled Google Earth image shows the location of the upper and lower breccias and our convenient pullout. Re: pullouts, YMMV.
The lower breccia, shown above, is easier to reach than the one high on the cliff, and is recommended if you don't feel like scaling the hillside. The lower breccia contains some large, generally elongated and subrounded carbonate breccia fragments in white calcite cement of varying thickness. The thicker, upper part of the white calcite looks vein-like to almost bedded.
Our goal, the white patch with one conspicuous dark gray fragment, is now obvious in the center of the photo.
Side-hilling up this scrabbly, brushy, talus-covered slope was tricky in places, especially where talus formed only a thin veneer over the bedrock, and where limestone beds jutted out unexpectedly, sometimes forcing a downward retreat.
MOH, on a ledge to the left of the breccia, provides a bit of scale.

This is a large breccia body with large fragments, somewhat remindful of the Titus Canyon breccia in Death Valley, though not as complex. The large to giant fragments are angular to subrounded, and are set in a matrix of coarsely crystalline white calcite. The breccia body, as exposed, appears to be mostly in one or two layers or beds of the Devonian Devils Gate Limestone; its shape could be subspherical (possibly cavern-like) or cylindrical (pipe-like).
Nearly the entire cliff face in this alcove is composed of breccia. For scale, the dark olive green ephedra bush near a curved breccia fragment (right of center) is about 3 feet high. Also, see the next photo for a closeup of the curved fragment and the same bush.
The curved fragment behind the ephedra bush shows primary layering or bedding, as does a second curved fragment below it.

Vertical to overhung cliffs of Devils Gate Limestone are towering behind me in the next shot, and I'm having trouble finding solid footing in the talus-ridden alcove. Talus was almost slithering down the slope, about to cascade over cliffy beds of limestone to the tear-a-pants rocks below. No boot-skiing allowed here, unless you know how to ski jump.
The breccia is mostly exposed in this one wall. The alcove may have formed from erosion of breccia; maybe it formed from erosion of solution caverns or caves no longer apparent and partly associated with the breccia. Here, I'm just speculating, as I don't really know the genesis of the breccia or the alcove. The curved fragment from previous photos is now above the 3-foot high ephedra bush and to the right, below and to the right of the large central fragment. From this angle, the curved fragment looks oval. Numerous smaller, angular pieces of dark gray limestone float in white calcite below it.

The ephedra bush suggests an apparent height or thickness of 20+ feet or 6+ meters for our breccia, but viewing angles are deceptive in the alcove.
Fragments are clast supported to matrix supported. One example of matrix support can be seen in the upper part of the cliff exposure, where the mass of calcite appears to be greater than the mass of fragments. It's possible that solution caving caused collapse of pieces and large blocks of limestone, which then concentrated toward the bottom of the collapsed area, leaving the upper area partly open after collapse and before later calcite deposition or infill.

The white breccia matrix consists of large, intergrown calcite crystals. White calcite veinlets in some fragments appear to be mostly, but not entirely, older than than formation of the breccia, and therefore older than the white calcite infilling event. I noted only a few places where late calcite veining appeared to cut across both the breccia fragments and its coarse calcite cement.

The age of all this activity — breccia formation, fragment cementing, and early and late calcite veining — is unknown to me.
An unidentified plant grows on coarse-grained white calcite in a narrows below the alcove.
Update: Identified by Hollis in comments as Petrophytum caespitosum.
Here's some more coarse-grained white calcite with a nicely reflective calcite crystal above my boot.

NOTE: More pictures of the calcite matrix can be seen here, along with one more shot of the petrophytum.
The same unknown plant is growing on dark gray Devils Gate Limestone in the ledgy area outward from the alcove.
We take one last look at the breccia before starting downhill.
The view from the ledge, looking west: Highway 50 and the partly parallel old highway angle across in the upper left; Slough Creek, surrounded by lots of rabbit brush, meanders through the foreground; Lone Mountain stands alone in the distance.
After making our way downward on some decent, though imperfect, boot-skiing slopes, we looked back at the breccia and wondered if the way we came down would have been easier as a route up than the scrabbly sidehill across loose talus.