Monday, June 20, 2011

Cathedral Gorge II: The Hike

After coming out of of "the cathedrals" at Cathedral Gorge, MOH and I went on a little hike.
The trail goes north up the gorge, from the CCC Picnic area (facilities and water tower built by the CCC in the 1930s) to Millers Point, a one way distance of about a mile (MSRMaps location).
Fascincating textures can be seen in the Pliocene Panaca Formation along the way. Here, differential erosion of harder, thin sandstone layers interbedded with softer mudstone layers have created interesting mini-columns and maybe even some little mini-cathedrals hidden in the shadows.
My hand is straddling two sandy layers and a mudstone layer sandwiched in between. A curious jigsaw-like texture has developed over the mudstone. Essentially these are tiny gullies or rills created by water running down the outcrop.
We've now made it into the beginning of the steep, northern end of the trail, and I've turned around to look southward down the gorge.
Steep: The northern part of the trail is steep, especially in this section of hand-built stairs held up by partially eroding railroad ties. Beyond these wooden steps are metal stairs that go from ledge to ledge over the steepest sections of the trail.
Instead of hiking the stairs all the way to Millers Point, we stopped on one of the middle ledges. Columns capped by sandstone can be seen from several vantage points along this northern stretch of the trail. The scale of these hoodoo-like features is difficult to appreciate: they are often smaller than similar erosional features at Cedar Breaks, for example. These are maybe two hundred feet high at most.
This is one of several holes eroding into the broad ledge we were standing on. I peered in, but couldn't lean out far enough to see anything, so tried holding the camera out as far as possible, having it do the peering for me.
I wondered if this hole could be the top of one of the cathedral-like columns we had seen from below while wandering around near the picnic area (first post).
An overexposed photo showed me that this hole only goes down a few feet (railroad ties for scale).
Some of the other "holes" and irregular erosional features near the edge of the ledge may indeed go downward to become cathedral-like inner columns, but I really didn't want to check them out too closely!
Now I've jumped two or three hundred feet upward and two or three years back in time to show this photo taken from Millers Point. The broad ledge we were on is below; the stairs to the right along with a smaller set of stairs down on the ledge (barely visible on the far left part of the ledge) give some sense of scale to the columns and gorge, and to the broad plain into which the gorge has been eroded. The bentonitic, tuffaceous clays, silts, and sands of the Panaca Formation — essentially water-laid tuffs, diatomaceous in places — were deposited in a closed, Pliocene-aged basin. The source of the tuffaceous material is reportedly the Caliente caldera complex south of Caliente, NV — way off in the distance on the far right — which was active in latest Oligocene to middle Miocene time, from about 24 to 13 Ma.

The Panaca Formation reminds me somewhat of the Triassic Chinle Formation, a partly bentonitic formation seen on the Colorado Plateau at the Painted Desert. Possibly the Panaca will look like the Chinle in the far future, if it has the good fortune to be preserved, rather than being eroded as it is now, southward into Meadow Valley Wash, from there southward into the Muddy River (formerly into the Virgin River), and from there into the Colorado. We are outside the Great Basin!
We finally headed back toward the CCC picnic area, just beyond that final rise of sand highlighted by the early afternoon sun.
Gratuitous sand photo. And darn! I forgot to collect any!

Some References:
Rowley, P.D., Nealey, L.D., Unruh, D.M., Snee, L.W., Mehnert, H.H., Anderson, R.E., and Gromme, C.S., 1995, Stratigraphy of Miocene ash-flow tuffs in and near the Caliente caldera complex, southeastern Nevada and southwestern Utah: in Scott, R.B. and Swadley, WC, eds., Geologic Studies in the Basin and Range - Colorado Plateau transition in southeastern Nevada, southwestern Utah, and northwestern Arizona, 1992, U.S. Geological Survey Bulletin, 2056-B, p. 43-88.

Rowley, P.D., Snee, L.W., Mehnert, H.H., Anderson, R.E., Axen, G.J., Burke, K.J., Simonds, F.W., Shroba, R.R., and Olmore, S.D., 1992, Structural setting of the Chief mining district, eastern Chief Range, Lincoln County, Nevada, in Thorman, C.H., ed., Application of structural geology to mineral and energy resources of the central and western United States: U.S. Geological Survey Bulletin 2012, p. H1-H17.

Nevada-Utah series so far (in trip-time order):
Cathedral Gorge I
Cathedral Gorge II: The Hike (this post)
May Utah Trip to be Continued
More Cross Bedding
Bighorns on the Overlook Trail


Gaelyn said...

Awesome examples of erosion. Love the cathedrals, both big and small, but wouldn't want to get to close to the edge. Looks like a great hike.

Silver Fox said...

Yeah, I don't like the edges much.

Desert Survivor said...

Very nice photos!

Silver Fox said...

Thanks, Desert Survivor!