NV-447 Lake Winnemucca (0803)

I think Lake Winnemucca was an arm of ancient Lake Lahontan. I wonder if that horizontal line you see on the other side is an ancient shoreline platform.

Those lines, that the makeup of that gray segment of mountains, were curious to me. I'll ask slgwv to comment...

Yeah, Winnemucca Lake is in the ancient Lahontan basin, but it was another modern remnant that dried up when water was diverted from the Truckee for the Newlands Project around Fallon. The diversion occurs at Derby Dam, where a canal takes off to dump Truckee River water into the Carson River drainage just above Lahontan Dam. So you have to distinguish between the modern dry lake bed (low down, out in the flats) and the older (and much higher) features related to Lake Lahontan. That interpretive sign Don photographed mentioned this a bit.
Those parallel lines across the valley, particularly well-defined on the left side of the photo (outlined), are indeed probably Lahontan shorelines, and that terrace is probably a shoreline bench. There's a complication, though: the range front of those mountains across the lake bed is defined by a large boundary fault, and that's responsible for some of the linearity. Sometimes fault scarps associated with recent breaks can look like shorelines. I don't think that's happening here, because the lines are so parallel to the lake bed and look to be following contours. Faults don't have to run along at exactly at the same elevation, and don't follow contours! There _is_ abundant evidence of large-scale faulting, tho; see the flat triangular faces terminating the ridges (outlined). Such so-called triangular facets are a common indication that the edge of the range is truncated, indeed defined, by a fault. Once you "get your eyeballs calibrated" you start to notice them all over the Basin and Range. (Sorry for the notes on your pic, Don--I hate it when people do that. They're just for illustration and feel free to delete them!)
Here's an old slide of mine looking more directly at the facets:
www.ipernity.com/doc/289859/22878267/in/album/439085
Btw, that gray rock is probably a rhyolite, but I haven't been over to check!
Here's another pic looking across farther north, away from the well-defined facets, also showing the shoreline features:
www.ipernity.com/doc/289859/22880809/in/album/439085

(A little editing to hopefully clarify my purple prose a bit--)

Don't mind the added notes at all, they're good for explanation and thank you for the detail.

From my reading of what you've written, the fault line would then be the east side of the lake running almost directly north / south at this point and the triangle shape slopes is from the shearing of those mountains. Looking at the satellite view gives a good indicator of the horizontal lines as former shorelines. Re the rhyolite, the extent of the flow is evident in the satellite photo, and it looks like there are some interesting (but probably difficult to navigate) roads into it. Given the coloring, would there be a likelihood of obsidian?

FYI, the Wikipedia page on Lake Lahontan seems good, indicating that Winnemucca was a remnant that dried up in the 1930's. en.wikipedia.org/wiki/Lake_Lahontan

My Eastern heritage doesn't give me a lot of experience looking at faults and their subsequent effects, as everything within 500 miles of me is old and buried. I'm so trained to look for the effects of water that I don't always think of anything seismic. But I can see what you're saying with those triangular faces, and now that I read that, I can think of a few other places where I might have seen similar features. Next time I go out there, I'll try to calibrate my eyes.

Thanks for the info!

Glad you found it of interest! I did my thesis back east (SUNY Stony Brook), and have one chapter on Appalachian geology. Most sections, however, were out west in Nevada and Utah. The joke in the dept. was that the students working on theses in the Appalachians spent their first field season locating the outcrops! ;)

Just another follow-up: about 20 years ago (gasp!) we took a graded road that turns off 447 to the right (north) outside Nixon. You end up dropping into the drainage of the old distributary channel from the Truckee that used to feed Winnemucca Lake. It's kinda poignant--you can see the stumps of the cottonwood trees that must've lined the river. It's all barren now--a bleak contrast! Since the diversion at Derby Dam, the Truckee has incised its main channel going to Pyramid Lake, so it would now require deliberate diversion to put water back in this channel. Haven't been back there, and of course got no pictures then. The area is on the Rez, so you're probably supposed to get a permit.

Btw, "Nixon" is not named after Tricky Dick but a Nevada senator from around the time of WW I. Dunno if he's a distant cousin!