On the summit of Peak 10242 with Signal Peak, the highest summit in the Pine Valley Mountains at 10,369' on the middle horizon, and Burger Peak far right.
Overview: Hike the entire steep "front face" of the Pine Valley Mountains with tremendous views of Zion NP, Yant Flat, Leeds, St. George area and southern Utah all the way to the Arizona border to summit its third highest peak with a great view of forested Signal and Burger Peaks, the Pine Valley Mountain Wilderness highest points.
Location: Utah - Dixie National Forest - Pine Valley Wilderness near St. George
Trailhead: Oak Grove Campground (37.31693 -113.45306) reached by taking Exit 23 to Leeds off of I-15, and traveling on Forest Road 032 to Oak Grove Campground.
Distance/Elevation gain: 8 miles/4,040'. Oak Grove T.H. = 6,530'. Lip of Pine Valley Mountains = 9,870'.
Coordinates: summit Peak 10242 = 37.33248 -113.47641. Oak Grove Trailhead = 37.31693 -113.45306
Date Hiked: 6/5/26
Maps/Apps: Trails Illustrated St. George-Pine Valley Mountains #715.
Geology: Pine Valley Laccolith - quartz monzonite porphyry. The Pine Valley Mountains are the largest laccolith in the U.S., and possibly the world.
Location: Utah - Dixie National Forest - Pine Valley Wilderness near St. George
Trailhead: Oak Grove Campground (37.31693 -113.45306) reached by taking Exit 23 to Leeds off of I-15, and traveling on Forest Road 032 to Oak Grove Campground.
Distance/Elevation gain: 8 miles/4,040'. Oak Grove T.H. = 6,530'. Lip of Pine Valley Mountains = 9,870'.
Coordinates: summit Peak 10242 = 37.33248 -113.47641. Oak Grove Trailhead = 37.31693 -113.45306
Date Hiked: 6/5/26
Maps/Apps: Trails Illustrated St. George-Pine Valley Mountains #715.
Geology: Pine Valley Laccolith - quartz monzonite porphyry. The Pine Valley Mountains are the largest laccolith in the U.S., and possibly the world.
For the Geo-curious: Pine Valley Laccolith
A laccolith is a large amount of magma that is injected between layers of rock, causing a dome-shaped mass. In this case, the Pine Valley Laccolith was a final surge of magma that occurred after the initial volcanic vents were shut off, causing the magma to be squeezed and move sideways between the layers of the Claron formation below it and the overlying magma layer. This injection, 22 million years ago, amounted to a 3,000-foot layer of monzonite porphyry, composed mainly of plagioclase and alkali feldspar. This is similar to granite, and when you look at a fresh surface of the rock, you can see the crystals, indicating the rock cooled slowly enough to form large crystals - allowing us to easily see them. The laccolith was uncovered when the volcanic layer above it eroded. The Claron Formation is made of limestone and mudstone; it is the rock that makes the spectacular hoodoos seen in Bryce Canyon National Park.
A laccolith is a large amount of magma that is injected between layers of rock, causing a dome-shaped mass. In this case, the Pine Valley Laccolith was a final surge of magma that occurred after the initial volcanic vents were shut off, causing the magma to be squeezed and move sideways between the layers of the Claron formation below it and the overlying magma layer. This injection, 22 million years ago, amounted to a 3,000-foot layer of monzonite porphyry, composed mainly of plagioclase and alkali feldspar. This is similar to granite, and when you look at a fresh surface of the rock, you can see the crystals, indicating the rock cooled slowly enough to form large crystals - allowing us to easily see them. The laccolith was uncovered when the volcanic layer above it eroded. The Claron Formation is made of limestone and mudstone; it is the rock that makes the spectacular hoodoos seen in Bryce Canyon National Park.
06/12/26
Summary of hike to Peak 10242 via Oak Grove Trail
Mile 0 - 3.1: Oak Grove trailhead to lip of mountain at 9,870' where trail descends to eventually meet up with Summit Trail.
Mile 3.1 - 3.5: continue on Oak Grove Trail through top forest to intersection with Summit Trail.
Mile 3.5 - 4.0: climb Peak 10242 eastern ridge to summit.
Since the Pine Valley Recreation Area is closed due to the 2025 Forsyth fire, we have two less trails to hike for elevation training (Brown's and Whipple on the north side of Pine Valley Mountain). We have discovered that Oak Grove Trail on the south side of the mountain is great for training because it climbs 3,300 feet in 3.1 miles. It's steep with spectacular views all way up, especially when you get to the lip of the mountain through the jagged monzonite cliffs.
Once we reached the entrance onto the top of the mountain at 9,870', we descended ~ one hundred feet onto a beautiful valley to the intersection with Summit Trail that extends for a distance east and west, bringing you within close proximity of the major peaks of Pine Valley Mountains. This portion of the Oak Grove Trail is cairned, as the trail is not so forthright in a few areas.
Once we hit the intersection, we headed straight up Peak 10242's east flank, climbing through severely burned tree trunks. I looked for the fire history of this peak and found it was close to the Forsyth Fire. I assume it's from this fire, but not sure. This is a moderately steep approach - straightforward with minimal downfall.
We reached Peak 10242 summit quickly, the third highest peak in the Pine Valley Mountain Wilderness behind Signal and Burger peaks, as it was only ~ 0.5 miles from Summit Trail. I did not find a summit register or survey marker. From the summit, Signal Peak, Pine Valley Mountains highest at 10,369' is easily seen to the southwest, as well as Burger Peak further to the north.
From the summit we found our way back to the intersection with Summit Trail with the use of CalTopo mapping app. The descent down the "front" of the Pine Valley Mountains is steep and rocky, with spectacular scenery to make up for that pain - almost.
The following photos are from two trips up Oak Grove Trail. The first time we did not summit Peak 10242 due to snow when we reached the 9,800' elevation.
Summary of hike to Peak 10242 via Oak Grove Trail
Mile 0 - 3.1: Oak Grove trailhead to lip of mountain at 9,870' where trail descends to eventually meet up with Summit Trail.
Mile 3.1 - 3.5: continue on Oak Grove Trail through top forest to intersection with Summit Trail.
Mile 3.5 - 4.0: climb Peak 10242 eastern ridge to summit.
Since the Pine Valley Recreation Area is closed due to the 2025 Forsyth fire, we have two less trails to hike for elevation training (Brown's and Whipple on the north side of Pine Valley Mountain). We have discovered that Oak Grove Trail on the south side of the mountain is great for training because it climbs 3,300 feet in 3.1 miles. It's steep with spectacular views all way up, especially when you get to the lip of the mountain through the jagged monzonite cliffs.
Once we reached the entrance onto the top of the mountain at 9,870', we descended ~ one hundred feet onto a beautiful valley to the intersection with Summit Trail that extends for a distance east and west, bringing you within close proximity of the major peaks of Pine Valley Mountains. This portion of the Oak Grove Trail is cairned, as the trail is not so forthright in a few areas.
Once we hit the intersection, we headed straight up Peak 10242's east flank, climbing through severely burned tree trunks. I looked for the fire history of this peak and found it was close to the Forsyth Fire. I assume it's from this fire, but not sure. This is a moderately steep approach - straightforward with minimal downfall.
We reached Peak 10242 summit quickly, the third highest peak in the Pine Valley Mountain Wilderness behind Signal and Burger peaks, as it was only ~ 0.5 miles from Summit Trail. I did not find a summit register or survey marker. From the summit, Signal Peak, Pine Valley Mountains highest at 10,369' is easily seen to the southwest, as well as Burger Peak further to the north.
From the summit we found our way back to the intersection with Summit Trail with the use of CalTopo mapping app. The descent down the "front" of the Pine Valley Mountains is steep and rocky, with spectacular scenery to make up for that pain - almost.
The following photos are from two trips up Oak Grove Trail. The first time we did not summit Peak 10242 due to snow when we reached the 9,800' elevation.
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Video on left reaching lip of Pine Valley Mountains to hike across to base of Peak 10242. Video on right is summiting Peak 10242, the third highest in Pine Valley Mountain Wilderness.
Caltopo map and elevation profile of our tracks from Oak Grove Campground to the summit of Peak 10242.
Google Earth images of the top of Pine Valley Mountain in foreground with Peak 10242 to the left, Signal Peak in the middle, and Burger Peak on the right. The top of the map points almost due south over Yant Flat and St George and Sand Hollow State Park upper left.
From the truck looking at the southern face of Pine Valley Mountains that we will soon be hiking!
Trailhead sign at parking lot and initial climb and intersection with Cottonwood-Harmon Creek Trail.
Initial view of southeast toward Washington and Zion National Park's silhouette on the left skyline.
View to the south with Forest Road 032 below (gravel road to Oak Grove Campground and Trailhead).
Ponderosa Pines start appearing ~ mid-hike. It's a straight-up 3 mile hike!
Finally to the top of Pine Valley Mountain face! Now we hike through the forest on top to find the base of Peak 10242.
Oak Grove Trail continues at the top to intersect with Summit Trail and a sign on it indicating to the east is Whipple Valley. Here we took a left (west) for a short distance to climb Peak 10242's southeast flank.
Lots of burned trees hiking up Peak 10242's east flank to the top. Our GPS tracks (white) and Rockd app identification of the rock unit we are in.
From the summit of Peak 10242 looking southwest to Signal Peak and west toward Burger Peak.