Photo of part of the east side of the Diamond Mountains, looking northwest from Highway 50.
I realized a while back, while going through old blog posts looking for specific reports and specific photos, that I really haven't done much of a post about Spencer's Hot Springs (a bit of one here). So, I started writing a post about a trip to Spencer's Hot Springs that MOH and I went on three years ago, describing the trip (briefly, of course), and this is where it went.
To get to Spencer's, we drove west on Highway 50, through Newark Valley, where I saw this part of the local stratigraphy on the east side of the Diamond Mountains (Google Maps location). I wrote some notes about what I thought I was looking at, locating the ever-present, widely recognized Mississippian Joana Limestone near the top of Newark Mountain, the cliffy limestone on the right side of the photo. From there, of course, the Pilot Shale would have to occupy the slope-forming part of the hill below the Joana, the Mississippian Chainman Shale would fill Tollhouse Canyon, the valley behind Newark Mountain, and the Pennsylvanian Ely Limestone would make up the hill behind the valley on the left side of the photo, with Fusulina Peak just beyond that Pennsylvanian horizon (MSRMaps). I thought I had the stratigraphy figured from the road, while passing by at 70 miles per hour.
Same photo as above, with approximate contact lines.
Here's the real stratigraphy, according to the White Pine County report: the cliffy limestone is the Devonian Devil's Gate Formation, a Guilmette Formation equivalent, the valley is composed of the Pilot Shale, Joana Limestone, and Chainman Shale, and the hill beyond is capped by the Ely Limestone (well, I got that one right, anyway!).
I was conducting what has been called x-mph geology, where x is the miles per hour one is driving; this time I was doing 70-mph geology. Geology at seventy miles per hour (or 70-mph geology) is generally much less detailed and often less accurate than geology at 20 miles per hour (20-mph geology). And it turns out that if you slow down to about 5 mph or less, you can almost complete a rock report on whatever iron-stained jasperoid or copper-stained porphyry you happen to be driving by, and the speed is almost slow enough for the geo-type in the passenger side of the truck to lean out and grab a sample.
The speed-geology terminology, along with an unrelated warp speed terminology, was invented by myself and another thermally altered geo-type back in the 1980s, probably while bouncing up and down some excessively rocky road in the Mojave Desert. Warp speed terminology is appropriate when gauging speed rather than geology: Warp 1 is 10 mph, a speed indicating that one is probably going steeply uphill or traversing one of those terribly rocky roads. Warp 2 (20 mph) is much preferred to Warp 1, but that still isn't much. If Scotty will give it all she's got, maybe you can get your speed up to Warp 4 or 5 on a dirt road, which is heaven, unless the washboard causes "She's breakin' up, Captain," in which case Scotty will have to wind the engines down to a more comfortable Warp 3 or 4. Also, Warp 4.5 to 5 on a dirt road can result in extreme turbulence when one comes over a hill and then bottoms into some unexpected washout on the other side. Scotty might then decide that, "She's comin' apart, Captain," which isn't a good thing no matter what warp you happen to be doing. Scotty has already resorted to, "I'm giving her all she's got, Captain!" Since that hasn't worked, you might then have to stop to regenerate your dilithium crystals (or have lunch or some other refreshment). Trees are in scarce supply in the Mojave, so the shade of your truck might be all you'll have for the precious dilithium to regenerate in.
I suppose I'll get into "thermal alteration" later; just know for now that it is more common in places where the hydro part of hydrothermal is in much lower supply than the thermal part, and that it can affect rocks, geologists, and prospectors alike. As for a Spencer's Hot Springs road trip, I guess that will have to wait for some other time: 70 mph geology took us from central Nevada into southern California!