Category Archives: geology

Modelo Mustard

Mustard flowering in Cheeseboro Canyon reveals the underlying structure of a hill.

Mustard flowering in Cheeseboro Canyon reveals the underlying structure of a hill.

According to the Dibblee geologic map of the area, the strata are part of the Modelo Formation. And… the Modelo Trail passes directly over the top of the hill.

The photo was taken on a run from the Victory Trailhead of Upper Las Virgenes Canyon Open Space Preserve to the Cheeseboro Ridge Trail and back.

Exploring the Lake Vista Trail and Ridge

Malibu Creek, Goat Buttes and Century Lake from Lake Vista Butte

This morning’s running plan morphed from doing a loop I’ve done many times, to exploring a trail I hadn’t done, and hiking along a ridge to the top of a butte with a unique view of Malibu Creek State Park.

Malibu Lake and Sugarloaf from Lake Vista Ridge
Malibu Lake and Sugarloaf from Lake Vista Ridge

I was running west on the Deer leg Trail, in the Reagan ranch area, when I stumbled onto the Lake Vista Trail. What’s this? I usually run the Deer Leg Trail in the opposite direction, and for some reason had not previously noticed this trail. Any trail with “Vista” in the name is worth exploring, so there was little choice but to turn onto the trail and see where it led.

As it climbed toward an obvious ridgeline, the enjoyable single-track trail wound in and out of various small canyons. About 0.7 mile from the Deer Leg Trail junction, the Lake Vista Trail topped out at a very pretty overlook of Malibu Lake. My watch showed the mileage to the overlook from the Cistern Trailhead was about 2 miles.

Lake Vista Ridge and Butte are between the Regan Ranch area and Malibu Creek
Lake Vista Ridge and Butte are o the left, with Sugarloaf in the distance.

From the overlook an unofficial “use” trail works back east along a broad ridge to the top of a butte that has a unique view of Malibu Creek, Century Lake and Goat Buttes. Because of the area’s volcanic origins, the use trail is rough and rocky in places, and the trail is not always obvious. It’s a little under a half-mile from the overlook to the summit of the butte. Even though it was Winter, I kept a wary eye and ear out for rattlesnakes.

Once back at the overlook, I made a loop of it by descending the Lake Vista Trail to the Reagan Ranch parking area, and then working back east on the Yearling and Lookout Trails to the Cistern Trail. Here’s an interactive, 3D terrain view of my GPS track of the run and hike.

A Sandstone Mammoth and a Spiral Labyrinth on the Bulldog Loop

A natural sculpture of a sandstone mammoth on the Backbone Trail

Instead of struggling to escape a tar pit, this “mammoth” seems to have been caught up in 25-30 million-year-old sandstone.

The beast can be seen along the Backbone Trail, east of the Corral Canyon Trailhead. When running/hiking/riding east from the trailhead, the trail climbs over two steep steps and up to gap in the rock. In the photo above, the gap is on the left and the mammoth figure is on the right. From the gap, the trail descends a rock corridor to Mesa Peak fire road.

A closer look at the mammoth reveals that it is pockmarked and there are rocks embedded in the sandstone. The embedded rocks are cobble from an ancient river and the pockmarks are where rounded rocks have fallen out of the eroding sandstone.

Spiral labyrinth constructed of ancient stream cobble along the Backbone Trail
Spiral labyrinth along the Backbone Trail

Stream cobble that has eroded out of sandstone formations in this area has been used to construct a spiral labyrinth on the north side of Mesa Peak Fire Road. The cobble was tumbled and smoothed by streams that drained a range much older than the Santa Monica Mountains.

The title photo is from this morning’s run of the Bulldog Loop.

Some related posts: Moon and Sycamores, Malibu Creek State Park; Bulldog Loop Near Corral Canyon

Looking for Boney Bluff

Boney Bluff from the Backbone Trail

Every time I’ve run the Chamberlain segment of the Backbone Trail, I’ve looked at the intriguing rock formation near the top of the trail and wanted to climb it. Looking a bit like an aircraft carrier that’s run aground on a mountain ridge, it’s one of the most prominent peaks along Boney Mountain’s western escarpment. Named “Boney Bluff” by rock climbers, several sport climbing routes were established on the southeast side of the peak in the early 2000s.

Located just northwest of the junction of the West Tri Peaks Trail and the Backbone Trail, the peak is visible from many points in Pt. Mugu State Park. According to lidar-based 1-meter resolution 3DEP data, its elevation is 2985′, which is slightly higher than the 3DEP elevation of nearby Exchange Peak.

Boney Mountain plateau.
Boney Mountain plateau. Click for larger image.

Boney Bluff is one of many small peaks and rock formations that are found across the Boney Mountain plateau. Comprised of a fused mishmash of volcanic breccia, the rock quality of these formations ranges from very good to quite bad. Seemingly solid handholds or footholds can break, and because of the way the rock erodes, low-angle sections are often littered with granular rocks that can be very slippery.

Boney Bluff from the east.
Boney Bluff from the east.

Having climbed the Western Ridge on Boney Mountain, I approached Boney Bluff from the north, via the Tri Peaks Trail. My route climbed a slope to the east side of the peak, then traversed right to the base of a jumbled face with several oddly eroded ledges. A short, steep crack and grassy ramp provided access to the ledges above. NOTE: There may be a better way to climb the peak. I was trying to do a relatively direct route and avoid bushwhacking. The route is somewhat manky, but worked for me.

Summit block of Boney Bluff
Summit block of Boney Bluff.

The high point of the peak is on top of a summit block that caps the “island of the carrier.” Many of the formations on Boney Mountain have summit blocks, and these are often the most difficult part of the climb. Rule #1 involving summit blocks: Don’t climb up anything you can’t 100% for sure climb down! This one looked like it might be tricky, but with careful route-finding was pretty straightforward.

Because Boney Bluff is perched on the edge of the Boney Mountain plateau, on a clear day there are outstanding panoramic views of Pt. Mugu State Park and the Boney Mountain area from its summit. Today, the visibility was excellent and Mt. Baldy was visible, 75 miles to the east.

Lidar-based 3DEP Elevation Estimates of Some Boney Mountain Peaks
Lida-based 3DEP elevation contours of Boney Bluff. Click for a larger image.

The resolution of the 3DEP Elevation Data is very impressive. While checking the elevation of Boney Bluff, I also noted the 3DEP elevation of several other peaks in the Boney Mountain area. For more info about 3DEP see this U.S.G.S. website.

  • Sandstone Peak 3116′
  • Tri Peaks 3039′
  • Boney Bluff 2985′
  • Boney Crest 2974′ (Accessed via Western Ridge or Cabin Trail)
  • Exchange Peak 2969′
  • Big Dome 2934′
  • Boney Peak 2849′ (Both summits)
  • Inspiration Point 2811′

Some related posts: Looking for Boney Mountain, Looking for Boney Peak

An Out-of-the-Way Trail, Two Peaks, a Wheelbarrow, and Washington’s Monument

Forsee Creek canyon from the John's Meadow Trail in the San Gorgonio Wilderness.

Wow, what a fantastic trail, canyon, and morning!

The view above is from the John’s Meadow Trail, a circuitous trail that winds its way through a less-traveled part of the San Gorgonio Wilderness.

Sugar pine cones
Sugar pine cones along the John’s Meadow Trail.

The prominent canyon in the photo is home to Forsee Creek. During the last ice age, it held one of San Gorgonio’s small glaciers. I’d just crossed the Forsee Creek a few minutes before, and in a few hours would run past its source high on the crest — Trail Fork Springs.

The peak at the head of the canyon is East San Bernardino Peak (10,691′). Its summit marks the crest of the divide and the location of the San Bernardino Peak Divide Trail. That’s where I was headed, but the path would be anything but direct.

From the Forsee Creek crossing at 7270′, the John’s Meadow Trail climbs about 1000′ in 2.3 miles to join the Divide Trail at “wheelbarrow junction,” about 5 miles west of East San Bernardino Peak. From that point I worked up the popular and scenic Divide Trail, visiting Limber Pine Bench (9330′), Washington Monument (10,290′), and San Bernardino Peak (10,649′) along the way to East San Bernardino Peak.

A weather-beaten lodgepole pine at Limber Pine Bench on the San Bernardino Peak Divide Trail.
Weather-beaten lodgepole pine.

Using this roundabout — but very scenic — route, it took me about the same time to reach San Bernardino Peak from the Forsee Creek Trailhead as it does to do San Gorgonio Mountain from the South Fork Trailhead. From San Bernardino Peak it’s a little less than a mile to East San Bernardino Peak and from there only about 0.75 mile to the lateral to Trail Fork Springs.

From the westernmost Trail Fork Springs junction with the Divide Trail the theme was downhill, downhill, and more downhill — about 3800′ of downhill over 6.7 miles.

The running on the Forsee Creek Trail was generally very good. I was glad I did the loop counterclockwise. The John’s Meadow Trail and its extension are enjoyably primitive — they appear to be “use” trails that have evolved over time. On the other hand, the Forsee Creek Trail is a constructed trail. It was designed as a pack trail, so is generally well-behaved. Great for going down, but a long haul up with a heavy pack!

San Gorgonio Mountain and San Jacinto Peak from East San Bernardino Peak.
San Gorgonio and San Jacinto from East San Bernardino Peak.

Here are a few photos taken along the way, and here is an interactive Cesium ion view of the GPS trace of my route. The 3D view can be zoomed, tilted and panned.

Note: Water is generally more reliable and accessible on the John’s Meadow Trail than on the Forsee Creek Trail. Trail Fork Springs and Jackstraw Springs are seasonal water sources that may not have water. Check with the Mill Creek Ranger Station for the current conditions and more info.

San Gorgonio Mountain Snow, Avalanches and Glaciers

Snow on the Sky High Trail on San Gorgonio Mountain on July 27, 2019.
Snow on the Sky High Trail on San Gorgonio on July 27. San Jacinto Peak is in the distance.

The weather was Southern California perfect. Shorts and short-sleeves were the dress of the day. Winds were light, no thunderstorms were in the forecast and no large wildfires polluted the air. Although temps in the valleys were nearing 100 degrees, the weather on the summit of 11,499′ San Gorgonio Mountain was altitude-conditioned bliss.

I’d spent about 15 minutes enjoying the summit, then run back down the Summit Trail. Turning left onto the Sky High Trail, I continued a keyhole loop that had ascended the South Fork Trail, Dollar Lake, and San Bernardino Divide Trails. Altogether, the route was about 21 miles long and the approximate elevation gain/loss was 4700′.

San Gabriel beardtongue (Penstemon labrosus) along the South Fork Trail.
Penstemon along the South Fork Trail.

From the start of the run, the effects of the wet 2018-19 Winter and big snowpack were everywhere. Wildflowers bloomed in profusion, seeps and small streams greened the landscape, and grasses and ferns grew thick beneath the trees. The roar of the streams at South Fork Meadows left little doubt as to what kind of Winter it had been.

On the way up the Dollar Lake Trail, I’d seen elongated patches of snow in the chutes along the crest. While there was no snow directly on the trail between Dollar Lake Saddle and the summit, there was more snow than usual on the north side of the peaks.

But there was snow on the Sky High Trail. Topping out at over 11,300′, the Sky High Trail is one of the most spectacular trails in Southern California. I marvel at its airy location every time I run it. Near the top of the trail, I’d crossed a small patch of snow and thought, “Well, at least there was a little snow on the trail.”

Large patch of snow on the Sky High Trail at an elevation of about 11,100' on July 27, 2019.
Large patch of snow on the Sky High Trail at an elevation of about 11,100′ on July 27, 2019.

A little disappointed, I’d put my poles away and continued running down the trail. At around 11,100′ I rounded a corner and surprise, surprise — there was a much larger patch of snow on a southeast-facing section of trail. It was about 100 yards across and steep enough that a fall would be a bad idea. Fortunately, the snow conditions were perfect. A few hikers had recently traversed the snowfield, and I followed in their footsteps.

However, that wasn’t the last of the snow. At an elevation of about 10,200′, not far past the C-47 crash site, the trail crosses a long chute that extends nearly to the top of Gorgonio. The snow in that chute had melted just enough that a thin strip of trail was exposed.

Thinking that had to be the last of the snow, I continued the traverse to Mineshaft Saddle (9936′) and began the descent of the Dry Lake Trail. Once past a rocky section of the trail, I picked up the pace, energized by the increased oxygen at lower elevation. Enjoying the downhill, I descended into an area of converging chutes and gullies, when the path through the lodgepole forest abruptly ended.

Avalanche debris on the Dry Lake Trail above Dry Lake. July 27, 2019.
Avalanche debris on the Dry Lake Trail above Dry Lake.

The trail was obliterated. Large trees were ripped from the ground, broken, tossed, and piled up as if they were matchsticks. Underneath the debris were mounds of dense, icy snow — the remnants of an avalanche. This report on SoCalSnow.org includes photos of an avalanche in February 2019 on the north face of San Gorgonio and mentions previous avalanches.

That snow, at an elevation of about 9400′, had finally been the last on the trail. Because the compressed snow is effectively a big block of ice, it could be around for a while.

In the area of the avalanche, the Dry lake Trail enters a large area of rocky rubble that extends into the Big Draw. According to the Dibblee Geologic Map for San Gorgonio Mountain, this rubble is glacial till, produced by the largest of several pocket glaciers that existed on San Gorgonio Mountain, Shields Peak, and San Bernardino Peak.

San Gorgonio Mountain's summit, on the left of the crest, is more than 2400' above Dry Lake.
This is the first time Dry Lake has been full this time of year since 2011.

Continuing down the trail to Dry Lake I saw where some of this season’s meltwater had gone — for the first time since 2011, Dry Lake was full in late July.

Last Saturday’s run was so enjoyable that yesterday I went back to Gorgonio and did it again. As might be expected during a Southern California Summer heatwave, the snow on the Sky High Trail, and elsewhere, is melting fast and won’t be around for long.

Here are a few photos taken along the way. The album includes photos from both the July 27 and August 3 runs. A couple of photos from a run on September 7 were also added.

Some related posts: San Gorgonio Mountain Snow Follow Up, Still a Little Snow in Southern California; San Gorgonio Mountain: Falls Creek Loop, August 2017; After the Lake Fire: The Dollar Lake – Dry Lake Loop on San Gorgonio Mountain