Bighorn Butte Bypass - 12/9/23

Tuff (hardened volcanic ash) at base of Peak 2555

Lake view from Tuff Area

Sheep Trail ridge line above Descent Wash

Starting up the Sheep Trail Ridge

During the research done for this entry, I learned:

    ..., the exposures of the Muddy Creek Formation here contain several volcanic ash layers. The age of these volcanic deposits is unknown, but the ash may have drifted to this area from large eruptions to the north in the vicinity of the Nevada Test Site.

    At (the area we hiked) on the skyline are the faulted remains of the volcano (Bighorn Butte and Peak 2555) from which much of the basalt in the northern part of the River Mountains was erupted. About 12 million years ago it may have resembled the broad shield volcanoes on the island of Hawaii.

    This area contains several small volcanoes or volcanic domes of Miocene age. The dark red and brown rocks that you see exposed along (Lakeshore Road) are the eroded remnants of these small domes and the dacite and basalt flows that came from them.

Sheep Trail high above the Wash

Peak 2555' in front of Bighorn Butte (2448') from Tuff Layer

Hiking into the Tuff Layer

Panorama inside the Tuff Layer

In this same area just past Lakeview Overlook toward Boulder City, the nature of the rocks changes completely. The first exposures of a geologic unit called the tuff (a light, porous rock formed by consolidation of volcanic ash) of Hoover Dam are encountered. This volcanic unit erupted explosively about 14.3 million years ago (during Miocene time) and may have originated from a caldera (a large volcano that collapsed after expelling its ash and volcanic flow rocks) just northwest of Hoover Dam.

~Geologic Tours in the Las Vegas Area (Expanded Edition with GPS Coordinates), Nevada Bureau of Mines and Geology Special Publication 16, University of Nevada, Reno, Mackay School of Earth Sciences, 2008, Bear Printing, Sparks, NV; pages 97,99,101.

Hiking through the Tuff Layer

Lake Mead from base of Peak 2555

Hiking up the small canyon Dryfalls

The small Canyon

Hopefully, this explains a few of our questions that we had on this hike into a colorful area at Lake Mead NRA. We parked at the Longview Overlook (which, btw, is missing a sign going in the southwesterly direction on Lakeshore Road. We crossed the road, the tortoise fence, the River Mountains Bike Trail and dove into the wide wash. Our goal was to find an old powerline road on the opposite side of the wash, climb up to the ridge line and begin to follow the sheep trail that runs along and aside this ridge. The sheep trail was a bit vague in the beginning but we soon found our footing and followed the trail all the way to the colorful area of hardened volcanic ash called tuff. We immersed into the tuff area and hiked up to the left along the wash finding sheep trails here and there. After doing this hike three times previously, I finally found the best track. Just keep going diagonally up leaning to the right until you see a small sandy wash below turning a corner. Head for that!

View down small canyon from Top

Fun Stuff

Seven nearby Bighorns

They see Us

Once before, we came down to the wash too soon and ended up having to climb up the Big Drop! Anyway, there is a large interestingly shaped boulder balanced at the bottom of a small ascent canyon. So, after reaching the wash below, we turned right into this canyon at the boulder. The washouts that happened during this autumn season have made all the dryfalls in this area a tiny bit deeper and we had to use the "up and arounds" on most of them. All the geodes that someone had used inside the canyon as cairns a couple of years ago have been transported back up the hill to where they belong so we didn't see any of them until we were climbing the hill at the top of the small canyon. We took our break among the geodes being fascinated by each one so I walked up the hill a little further when everyone sat for a break.

They aren't interested in us.

Something (not us) spooked them and off they went!

Dropping back down the small Canyon

The Big Drop

Just over this hill, I saw seven bighorn sheep gathered. After taking a few photos, I returned to the group snacking behind me. (I didn't want to yell!) In the end, only half of the group understood me and came quickly to view the spectacle. The bighorns put on a show at the end when, without us making any noise from a good distance away, they suddenly turned and ran, then turned and ran the other way, stopped, then turned and ran around the back of the next hill. They were running and turning very much like a flock of birds flying in the sky taking cues from a quiet leader in the flock. We were all thoroughly entertained. Finally, we returned down the small canyon and came to the Big Drop scramble. There were a few more scrambles ending with a visit to the arch for a group photo. Next, we were in a wide wash speeding toward our cars over a distance of about 1.25 miles. Everyone seemed to be up to the task. What a fun day! This is certainly a hike that keeps your interest!

Stats: 5.6 miles; 1200' gain; 4 hours

Big Drop Fun

Group shot at the Arch

1.25 Mile Descent through the Wash

Track Maps combining the Bighorn Butte Bypass track with the Bighorn Butte Track