Across the West and Back Day 2: Beyond the Wasatch

It was a cloudy and soon to be stormy day, and we were just about over the Wasatch, just about to U.S. 189, which runs in a northeasterly direction through Provo Canyon toward Heber City, where we planned to meet up with U.S. 40. On our way to 189, still on S.R. 92, we passed by one or two roadcuts exposing some tilted beds, a general configuration that was rapidly becoming familiar on our trip, one I soon came to think of as "another tilted section." In this case, it turned out that we were looking at the basal member of the Oquirrh Formation: the Bridal Veil Limestone.

Bridal Veil Limestone member of the Oquirrh Formation, Pennslyvanian in age.

I found out later—from Geolex—that this medium to dark gray, thick to thin bedded limestone, which was named for Bridal Veil Falls on the south side of Provo Canyon, is about 1200 ft thick.

We made it into Provo Canyon. About 3 miles up the canyon, Highway 189 crossed from the north side of the canyon to the south side, ending up south of the dammed Provo River at Deer Creek Reservoir.

We started seeing some modified roadcuts.

A modified roadcut of the Bear Canyon member of the  Oquirrh Formation.

These types of roadcuts, where the steep rock exposures appear to be cemented for slope stabilization and then painted or stained to look somewhat like natural rock, became another hallmark of our trip, being seen fairly commonly at least in Utah and Colorado. I found these types of roadcuts to be fascinating, and I consider them to be better (more scenic? an attempt at a "natural" look?) than some types of wholesale roadcut destruction.

An original part of the roadcut can be seen in the gully ahead, although I imagine it might be hard to examine.

Moving along past Deer Creek Reservoir, we finally came into a downpour. Visibility was worse than shown in this photo, for several miles. We were entering the part of the west that was having an abnormally wet monsoon, although we didn't realize how wet it would really be until later.

With it still raining, we finally hooked up with U.S. 40, which we had lost in Salt Lake City before we started our unplanned side trip through the Wasatch via American Fork Canyon and Utah S.R. 92.

When I first started this series last summer or fall, I was really planning on doing more with it than I seem to have time for now, and I was planning on making notes about the geology on the road trip and the formations being seen in these photos. I also have been keeping the locations of photos up to date on the map seen in the last post (link here, not updated at the moment). I'm finding this level of detail to be just too much at this point, so am going ahead with things the way they are right now.

What I noticed when looking up info about the rock formations on this part of the trip and in the last post, was that it's possible that the Bear Canyon member of the Oquirrh Formation and Ely Limestone may be at least in part correlative (also mentioned here). It's a similar age (or the same?), reportedly has abundant nodules of black chert (Geolex), and some fossils in certain parts of the Oquirrh have been tentatively identified in rocks possibly correlative with the Ely (1998 paper here).

Selected References:
Baker, A.A., and Crittenden, M.D., Jr., 1961, Geology of the
Timpanogos Cave quadrangle, Utah: U.S. Geological Survey
Geologic Quadrangle Map, GQ-132, 2 sheets, scale 1:24,000.

Interactive geologic map of Utah (UGS)

My initial notes: Bridal Veil overlies Manning Cnyn Shale, but although the next formation we see looks like it could be a shale, it's more of the Bear Canyon Member of the Oquirrh. This was named as the basal member of the Oquirrh Fm in an area where the Bridal Veil Limestone does not occur or doesn't otcp.

Geloex (Bear Canyon): says "gray to tan and reddish-brown, limy to quartzitic sandstone with thin to thick beds of gray to black limestone, in part sandy, and in part with abundant nodules and stringers of black chert" -- both of these units, their age and description (and not so much what I've seen of their otcp or exposure) remind me of the Ely Limestone, which we saw here and here (search blog="oquirrh" for one, including "ely") (blah blah). And indeed, the fossils within certain parts of the Oquirrh have been tentatively identified in rocks possibly considered part of the Ely (1998 paper here)

Going back to Roberts Horn (last post) and here - it might even look like the Ely!

Related Posts:
Across the West and Back Day 2: Over the Wasatch Range
Across the West and Back Day 2: Are We Lost Yet?
Across the West and Back Day 2: A Hike along a Limestone Ridge
Across the West and Back Day 2: Across the Salt Lake Desert
Across the West and Back Day 2: A Side Trip in West Wendover
Across the West and Back Day 2: Pequop Summit to West Wendover
Across the West and Back Day 2: Looking for an Old Roadcut
Across the West and Back: The First Day
Intro to Recent Western Loop Trip

Across the West and Back Day 2: Looking for an Old Roadcut

We left Elko early on the second day and stopped at a little cafế in Wells for breakfast.

I couldn't help but take a couple photos of the interior (!).

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A Relevant Aside: Because this part of the trip was across the route of Historic U.S. 40 (now mostly defunct and nowhere signed in Nevada), the drive took me back in time to a cross-country family trip made on U.S. 40 from the west to east coast in 1957, then back east to west about a year later. I was quite young at the time, so have only a few vignettes from the trip stored in my memory. One is of a roadcut somewhere in the west, where we stopped, and I collected my first specimen of slate.

Much later, on a field trip the first year I came to Nevada for grad school — or on a trip to the GSA meeting in SLC that same fall, I saw the roadcut, and it was like dếjấ vu all over again — except this time I *had* been there, about two decades prior. The roadcut, therefore, was either on a section of I-80 between Battle Mountain and Elko (there are very few roadcuts west of Battle Mountain), or on a then still extant section of U.S. 40 between Carlin and the Utah border where I-80 was incomplete. I saw the roadcut then; maybe I saw it again on a 1982 trip to SLC for the GSA Cordilleran section meeting. Have I seen it since? Not sure.

I-80 through over Pequop Summit was still shown as not being completed on the 1987-1988 state highway map, and it was only shown as complete upon the issuance of the 1989-1990 map (I find it hard to believe that the interstate was only completed sometime between 1987 and 1989 or so, but there it is). Also see the 1975 map for the then current state of affairs during my first couple trips across the state that fall.

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Back to the trip: At about 8:20, we started up the west side of the Pequop Mountains and began seeing our favorite limestone: the Ely Limestone (or maybe it's called something else in northeastern Nevada, like Etchart?). This section of road probably closely follows the original route of U.S. 40 through the mountains, and it goes through exposures of bedded to flaggy-looking Ely Limestone and shaly Chainman Shale below that.

Ely Limestone.

In the Pequops, I thought I saw a couple roadcuts that looked like the one I remember from long ago, but the ones that really struck me are probably in Ely Limestone.

Looking carefully at the satellite view of the area on Google Maps, I can deduce that the [articular roadcut shown below might be (partly) in Chainman Shale, although really, most of the exposure looks like limestone.

Ely Limestone on the right, a fault in shadow in the upper left; possible Chainman Shale left of the fault (barely in the photo).

By the time we were approaching the Pequop exit on the east side of the summit, I had seen several possibilities for the original roadcut, but I'm not sure that any of them fit the bill. Perhaps it was in the westbound lane on a section where the lanes diverge. Perhaps the roadcut has been modified beyond recognition since I last saw it. Perhaps it was really on some other leg of U.S. 40 in Nevada or Utah. In any case, I enjoyed seeing the Ely Limestone through this part of the trip and recognizing the Chainman Shale in exposures below it (mostly in the surrounding hills and not in the roadcuts) .

We approach the Pequop exit and can see part of the Toano Range across Goshute Valley.

I'm going to stop here for now, otherwise this will never get posted! I've got the Day 2 trip route in Google Maps below, with locations of photos taken during the day — I'll add to this as I post more photos. I've also shown several roadcuts of of interest where I took photos, roadcuts I later decided were most likely in Ely Limestone. Note the conspicuous divergence of the eastbound lane from the westbound lane in the middle of the Pequops. This divergence leaves a roadcut possibility to check out on some other trip.

View Day 2: Elko, NV to Vernal, UT in a larger map

Related Posts:
Across the West and Back: The First Day
Intro to Recent Western Loop Trip

How to Make Coffee Strandlines or Rhythmites

Once upon a time, MOH and I left suddenly for an unexpected trip of unknown time duration, and I failed to empty all the coffee cups. Upon arriving back, having been gone most of 14 days, I tentatively looked in my cup expecting to find terrible mold, instead finding these lines of coffee deposited around the side of the cup.

"Varves!" I exclaimed, "Except they aren't from yearly deposits, they're from daily deposits!"

I've reflected a little, and asked a few close-at-hand sources, and decided these aren't really varves — and they probably aren't really rhythmites, either — for the simple reason that varves and rhythmites would be layers, of concentrated coffee in this case, that would have been deposited in the bottom of the cup. Instead, these must be more akin to strandlines — or shorelines around a coffee lake, in this case — as suggested by @GeoTheoBO. Other suggestions for what to call these deposits were Stratified Caffineite (@CGKings317), rhythmites (@alexbirtwisle), and my favorite, "Jarves" from "Java-varves" (@Dhunterauthor). Everyone else is welcome to jump into this discussion and naming exercise in the comments.
Prior to deciding that these were really the results of daily evaporation of coffee, I did count the rings. There are 13, with a possible incipient 14th one near the bottom representing the partial 14th day during which we arrived back in time to check the cup. The lines I've drawn above are based not just on the locally fuzzy record shown in that one photo, but on the three photos I took documenting the entire stratigraphic record around the entire inner part of the cup.
Here are the final determinations. A few of the days are a little fuzzy and the lines have been brought in from the side, just like you might have to do when correlating deposits out in the field. Most day's deposits are light toward the bottom and darken upward, possibly reflecting something having to do with diurnal temperature and humidity variations. To be honest, I don't really know when the darkest portion of each day's ring forms, whether at night, during the day, or at some other time. The cup was sitting on the kitchen counter in the sunlight of the window the entire time we were gone; evaporation would presumably have been strongest during the daylight hours, possibly resulting in the lower, lighter colored part of the layer. Any other thoughts?

This post has been submitted to the Bake-Sale Accretionary Wedge (AW#30), though no baking was involved.

UPDATE: Accretionary Wedge #30: the Bake Sale is now up at Mountain Beltway. It's a very yummy Wedge, I might add.

Three Years Ago Today: Newark Valley Geology at 70 Miles Per Hour

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!