Virlis Fisher Arch / Bridge Spring Natural Bridge Loop - 2/10/22

Kay's Archive Photo of Snow-Covered Spring Mountains through Virlis Fisher Arch (2010)

Tuff of Bridge Spring formed 15.2 Million Years Ago

Overlook of the Colorado River north of Nelson, NV

Following Washes

The Bridge Spring formation is located in the Eldorado Wilderness which, in turn, is located between I-95 and the Colorado River southeast of Las Vegas, Nevada. This area is filled with craggy cliffs and softer mounds and peaks of ancient volcanic ash flow tuff. Andesite and tuff is what makes the colorful bands that you can see from SR 165 as you approach the trailhead found 10 miles from 95 as you head toward Nelson, Nevada. More information on the Eldorado Wilderness can be found at https://www.nevadawilderness.org/eldorado_wilderness. 

Specific geologic description can be found at https://digitalscholarship.unlv.edu/cgi/viewcontent.cgi?referer=&httpsredir=1&article=2454&context=thesesdissertations, a masters thesis from UNLV. The author, Ms. Morikawa, speaks in very technical terms but there are a few tidbits of information that the lay person can glean. 

Tuff of Bridge Spring

Small Break

Snowy Spring Mountains from Eldorado Wilderness

Ralph in Descent Wash

To put things in simpler terms, Wikipedia says:

Andesite is an extrusive volcanic rock of intermediate composition. In a general sense, it is the intermediate type between basalt and rhyolite. Tuff is a type of rock made of volcanic ash ejected from a vent during a volcanic eruption. Following ejection and deposition, the ash is lithified into a solid rock. Rock that contains greater than 75% ash is considered tuff, while rock containing 25% to 75% ash is described as tuffaceous (for example, tuffaceous sandstone). Tuff is a relatively soft rock, so it has been used for construction since ancient times. Tuff can be classified as either igneous or sedimentary rock. It is usually studied in the context of igneous petrology, although it is sometimes described using sedimentological terms.

     

Descending Scramble to Valley Wash

Seven at the Meeting Rock

Three at Virlis Fisher Arch

Kay's archive photo of Virlis Fisher Arch (2018)

My favorite reference book for geological explanations, 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, page 108) gives us: 

The small quarry cut into the side of the hill to the left exposes the tuff of Bridge Spring, a regionally extensive ash-flow sheet that erupted from a caldera in the Eldorado Mountains about 15.2 million years ago. The hills extending away from the road to the left are thought to be composed of a thick section of this tuff that was deposited against the wall of the caldera. The caldera wall, and the tuff, has been tilted 90 degrees onto its side. The tuff exposures are cut by a left-lateral strike-slip fault (such as faults of the Lake Mead fault zone) that represents an adjustment or tear fault in the upper plate of a major detachment sheet. This unit is named after Bridge Spring, located about 2 miles north of Nelson and about 1 mile east of SR 165.

Another view of the Colorado River Overlook

Leaving the Overlook

Through the Rabbit Hole

View back toward the Arch and Overlook

As we did last year, we hiked the two arch loop in a clockwise direction starting to the west of the trailhead parking. Today, there were seven of us. We weaved our way through the washes and ended up at the bare saddle up among the tuff. The wash on the other side is a fun rocky scramble. At the bottom, we turned left and continued the fun. During this next section, you can turn right at any time to make your way over and down to the main valley wash that runs north/south. In this main wash, you can see Virlis Fisher Arch protruding from the cliffs to the east. There is no trail, per se, but, suffice it to say, the best way to reach the base of the arch is to find the "Meeting Rock" directly down the hill from the arch and climb up from there.

Happy Hikers

Steep Descent down to Bridge Spring Natural Bridge (aka Nelson Arch)

On the Steep Descent

Three on Bridge Spring Natural Bridge

After explorations of the arch, find a vague game trail leading from the base of the cliffs over to the river overlook saddle to the south.There are about three game trails and Mike found another one today!! The river view was fantastically clear. Then, we continued around and down to the other side of the valley where there is a rabbit hole and trail up to the top of the hill. The trail leads down through a saddle and around a corner to the top of the canyon that holds Bridge Spring Natural Bridge (aka Nelson Arch). The trail leads steeply down into the canyon where there is a choice about midway as to whether you wish to go to the top of the bridge and down climb on the other side or continue down to the wash and climb up under the bridge.

Two under Bridge Spring Natural Bridge

Three descending from top of Bridge Spring Natural Bridge

Seven under Bridge Spring Natural Bridge

Climbing the Wash from the Natural Bridge

After we took our group photo under the bridge, we followed the wash up until we came to a junction where we could turn left toward some light colored boulders. There is a misleading trail that climbs the embankment at the 11:00 direction. We followed the wash that eventually became a trail. This trail wound around until we topped a ridge and started dropping down toward the trailhead. The entire streamlined loop was about 4.5 miles but therein lies a lot of fun scrambling with interesting landscape surrounding. There are several other arches and caves to explore in the area as well. The Fearsome Foursome enjoyed hiking with George, Charlie and Ralph today!

Stats: 4.5 miles; 900' gain; 3.5 hours

Scrambling with Style

The last climb back to the Cars

Last view of the Tuff of Bridge Spring