Hike Rencher Peak - 8,788': Volcanoes for a Change!

Enjoy solitude and unique volcanic terrain when you hike this fully forested, obscure peak whose trail intersects with Summit Trail leading south into the Pine Valley Mountain Wilderness.

Leaving Long Flat Trail to hike towards Rencher Peak summit.

directions

Related Posts:  Mt. Baldy, 8,890'.    Signal Peak, 10,369'.    Burger Peak, 10,320'

Trip Stats
Location:  West of New Harmony, Utah - Dixie National Forest - just north of Pine Valley Mountain Wilderness 
Distance/Cumulative elevation gain:  Out and back 9.2 miles/2,460'   Upper Grants Ranch TH = 6,608',  summit = 8,781'
Coordinates:  Trailhead = 37.53596  -113.37819.  Summit = 37.50178  -113.41146
Prominence: 781'
Date hiked: 8/09/25
Maps/Apps:  National Geographic Trails Illustrated #715 - St. George/Pine Valley Mountains.  Cal Topo Map
Geology:  Rencher Peak is a vent that erupted lava flows of latite during the Pine Valley Mountain laccolith eruptions.  Pine Valley Latite is a gray, black and pink flow-foliated rock, 20 million years old.  Flow foliation is a layering and banding of volcanic lava, created by frictional drag and temperature gradients; as the outer edges of the lava cools, the inner layer is still flowing, creating a layered effect.
​Quote:  "And many a fire there burns beneath the ground."   -Empedocles

​Hike Summary via Upper Grants Ranch Trail
0 - 2.2 miles:  Upper Grants Ranch Trailhead to intersection with Summit Trail
2.2 - 2.6 miles:  Intersection of Summit Trail and Long Flat Trail
2.6 - 4.1 miles:  Long Flat Trail to turn-off to the southeast to climb Rencher Peak
4.1 - 4.6 miles:  turn-off to summit

I can't believe I'm saying this, but Fred and I actually needed a change from hiking the usual gorgeous southern Utah red sandstone wonders like Zion and Red Mountain Wilderness so near to us.  

So, we started hiking in the ash, crystal and glass-filled igneous rocks in volcano country.
​
Rencher Peak fit the bill - something different with substantial elevation gain.  It's a pretty obscure peak north of Pine Valley Mountains' Signal Peak and Burger Peak, the higher, more popular destinations.  It reminds me of Mount Baldy, another obscure summit in the vicinity of the Pine Valley Mountains.  Both Baldy and Rencher's trailheads are out of New Harmony, a small town to the west of the Kolob section of Zion National Park.  Both require cross-country navigation off an established trail.

We're discovering there's a lot more to be seen in southern Utah besides "Utah's Mighty 5" national parks - Arches, Bryce Canyon, Canyonlands, Capitol Reef, and Zion.  Extensive igneous intrusive and extrusive (volcanic) terrain spreads in a northeast-trending mass north of these parks.  Near Fish Lake and Torrey, we discovered the extensive aspen groves and volcanic rocks of the huge Marysvale stratovolcanic field and hiked Hilgard Mountain and Fish Lake Hightop.

All of these places we have been exploring have one big thing in common:  Rencher Peak, the Pine Valley Mountains, Hilgard and Fish Lake Hightop share the same deep, underlying magmatic system where 20 million years ago, injected magma became quartz monzonite and ejected magma became rhyolite and dacite during huge pyroclastic events.  The intrusions grew so fast that the rock over them "unroofed", causing enormous gravity slides, exposing vents that spewed magma, including what is now Rencher Peak.  Some geologists call this huge territory the "Iron Axis", because of the iron ore found and mined in this area.   

For the "Geocurious":  almost identical magma, different names
Not a lot of people know that the Pine Valley Mountains, just south of Rencher Peak,  may be the largest exposed laccolith in the world.  A laccolith is formed when magma is forced up through a conduit and spread between sedimentary layers, forming a dome-shaped top and a flat bottom.  The magma spreads horizontally, forcing the layer above it to dome upward.  Erosion over time or "unroofing" by rapid and voluminous flows peels away the overlying layers, exposing the laccolith, which is more resistant to erosion. 

Rencher Peak's and the Pine Valley Mountain's rocks have nearly the same chemical composition since they were formed during the same igneous event 20 million years ago.  The only difference is the amount of quartz in each rock.  Pine Valley Mountain's rocks were formed underground (intrusive) and are made of quartz monzonite.  Rencher Peak's rocks were volcanic (extrusive) and formed after being erupted from a vent and are latite.  Latite is the volcanic equivalent of monzonite.

Possible reasons for the lower quartz content in latite is that it has a lower silica content to begin with and/or it didn't undergo the same differentiation/evolution of minerals during the cooling process because it cools faster than intrusive magmas, limiting time for large crystals to grow.

​Our Hike
​The first few miles of Upper Grants Ranch Trail is very silty and dusty.  I kept wondering why the trail was cut so deeply into the ground with high sides.  At 1.3 miles the very rocky trail begins to climb as it contours around a high point climbing the right side of a wide, highly vegetated gully.  At about 2.2 miles, on a saddle, it intersects with Summit Trail which leads southward to the big peaks in the Pine Valley Mountains:  Signal and Burger.  You follow Summit Trail south for 0.4 miles to its intersection with Long Flat Trail.  You take a right (west) onto Long Flat Trail.  This is the access trail to the base of Rencher Peak for the summit approach.

Interesting volcanic rock towers and formations line up along each side of the trail.  This has to be one of the most unique trails I have been on because it's a grazing area combined with weird rocks that definitely weren't granite or tuff.  Some of the rocks had "layers" in them - "flow bands" - I found out after reading more about latite, the rock unit present here.  Flat rocks near a gully with lots of trees had symmetrical holes that looked like mortar holes that native Americans may have used, but they also could have been potholes formed by water and algae - altered chemicals.

Another unusual aspect was the lack of other hikers in this area despite the interesting terrain and the network of trails.  Perhaps hikers knew of the devastating Forsyth Fire this year (2025) that closed Pine Valley Mountain Wilderness.  We saw only one other hiker on Summit Trail.

Long Flat Trail that takes you to the base of Rencher is faint in some places - my Topo Maps US app helped me find the general direction.  The trail was marked in places with rock "ducks".   

Once we reached the northwest flank of Rencher Peak, we saw a faint trail leading up towards the summit and followed it until we came across pretty open meadows filled with rubber rabbitbrush and its golden blooms.

We hiked to the highest point we could find - a few boulders surrounded by trees and brush.  Most of the summit was forested with occasional pockets of openings to view meadows and grazing areas below us.  

Not a magnificent summit, but glad we discovered new territory, new volcanic rock, and got some decent elevation gain.  I'm sure we'll explore more of this area.  Glad we have options!

Trailhead sign for Upper Grants Ranch Trail.  The red outline on the map below illustrates the extent of the recent and devastating Forsyth Fire in the Pine Valley Mountains.

Starting off on Upper Grants Ranch Trail.

Gordon Spring - an old trough with algae-covered water 0.5 miles in.

Trail beginning to climb as it contours around a high point, first south, then northwest.

Out of the forest, heading up through gully toward saddle on top of ridge.

Getting closer to saddle and intersection with Summit Trail.

Pretty meadow on the pass with lots of curl-leaf mountain mahogany trees and sagebrush.

Looking back at Kolob Canyons section of Zion National Park, town of New Harmony in the valley.

Trail becomes a two-track.  Nearing the intersection with Summit Trail - follow it to the left (south) to Long Flat Reservoir.

First view of Rencher Peak ahead.  The approach is up the right side of the peak.

Curl leaf Mountain Mahogany - the fuzzy stems are its seeds that with strong winds detach and propagate.  These trees grow well in shallow, rocky soil and their extensive root systems stabilize this soil.  They can live hundreds of years.
Cercocarpus ledifolius

Double track leads down into Long Flat with its now-dry reservoir.  The trail goes around this to the right.

Sign at second intersection with Summit Trail and Long Flat Reservoir.  Take a right (west) onto Long Flat Trail.

Heading west between large volcanic rock formations.

Hiking west through grass and juniper meadows.

There's a few cow trails leading here and there, just stay on the main trail and walk around to the southwest.

An example of flow-banding in the Pine Valley Latite rock.  You can see the flow lines of the lava as it solidified and cooled.  This lava is high in silica which makes it thick and viscous.  The bands could be due to friction of the lava against a more solidified rock, or alignment of crystals into layers.

Pine Valley Latite!

Rencher Peak ahead!  Heading to the right side of it.

Some pretty aspens

At first glance these holes look like mortar holes that native Americans used to grind seeds, because they look so symmetrical.  But they may just be potholes eroded by water.

Getting closer to Rencher Peak's northern flanks, which we will climb in a southerly direction to its summit.

There's a few "ducks" or trail markers on this Long Flat Trail section.

Leaving Long Flat Trail at 4.1 miles into the hike to climb southward to the summit.

There's a trail until you reach the open meadows on the north flank of Rencher.

Once we reached open meadows, we lost the trail and just headed straight up to the summit.

A view to the west.

From near the summit, a view to the south in the direction of Pine Valley Mountains of Timber Mountain on horizon, and White Rocks Reservoir in valley bottom.

The summit is forested with some brush to wade through.  

References
Cook, E. 1957.  Geology of the Pine Valley Mountains Utah.  UTAH GEOLOGICAL AND MINERALOGICAL SURVEY.

Biek, R., et al. 2010. GEOLOGIC MAP OF THE ST. GEORGE AND EAST PART OF THE CLOVER MOUNTAINS 30' x 60' QUADRANGLES, WASHINGTON AND IRON COUNTIES, UTAH.  Utah Geological Survey.

Mc Nair, B.  2023.  What You Must Know about Monzonite Rocks.  Geology Base