Mormon Rocks in the Cajon Pass: Geology, History, Visiting

The Mormon Rocks are tilted sandstone cliffs along State Route 138, just west of Interstate 15 in the Cajon Pass. They are part of the San Bernardino National Forest, and an easy loop trail of about 1 mile leaves from the Forest Service's Mormon Rocks fire station, where parking is free. Movement near the San Andreas Fault shaped the rocks, and they carry the name of the Latter-day Saint wagon party that crossed the pass in 1851.

Where are the Mormon Rocks?

From I-15 in the Cajon Pass, take the State Route 138 exit and go west toward Phelan and Wrightwood. The Forest Service trail page puts the trailhead at the Mormon Rocks fire station, on Highway 138 a short way west of I-15. The trail begins near 3,360 feet.

The same page lists the Front Country Ranger District office at 1209 Lytle Creek Road, Lytle Creek, (909) 382-2851. It is open Wednesday through Sunday, 8:00 am to 4:30 pm, and closed Monday and Tuesday.

Our Hesperia community guide and High Desert hotspots list cover more nearby outings.

How were the Mormon Rocks formed?

The Front Country Ranger District trail brochure describes the rocks as beds of cemented sandstone. Earthquake activity along the nearby San Andreas Fault lifted them and stacked them at an angle.

USGS mapping of the next quadrangle over, Telegraph Peak, adds detail. The USGS report (Open-File Report 90-693) maps the Cajon Valley rocks as Miocene-age conglomerate and pebbly sandstone, layered with finer sandstone and siltstone. It also maps several faults nearby:

• San Andreas Fault: follows a narrow rift valley, Lone Pine Valley.
• Cajon Valley fault: moved during the middle Miocene.
• Punchbowl fault zone: an older, ancestral strand of the San Andreas system.

An early USGS guidebook, Bulletin 845, explains how the gap formed. Narrow blocks of schist and soft sandstone sit between closely spaced faults. Wearing away of the sandstone on the dropped blocks is, in its words, "the principal cause of the pass."

Why are they called the Mormon Rocks?

In March 1851, a party of 437 Latter-day Saints set out from Great Salt Lake City with about 150 covered wagons. Their goal was the San Bernardino Valley, and church apostles Amasa M. Lyman and Charles C. Rich led them. PBS SoCal notes that the Mormon Rocks name still marks their trip through the Cajon Pass.

Before 1851 ended, the settlers had purchased Rancho San Bernardino from the Lugo family. They built Fort San Bernardino, enclosed by a 12-foot stockade. Brigham Young called them back to Utah in October 1857, and close to half chose to stay in California.

What historic trails pass through here?

People used the Cajon Pass long before 1851. The National Park Service places it on the Old Spanish National Historic Trail and says travelers have used the canyon for thousands of years to get between the Mojave Desert and the Los Angeles Basin. NPS adds that the Pacific Crest Trail crosses the pass, in part alongside the Old Spanish Trail route.

The Forest Service trail page says the historic Mormon Trail of the 1800s ran through this valley. USGS Bulletin 845 adds that 1849 gold seekers used the same route heavily.

The Santa Fe and Salt Lake Trail Monument

Nearby is the Santa Fe and Salt Lake Trail Monument, registered as a California Historical Landmark in 1957. The California Office of Historic Preservation lists it at the south end of Wagon Train Road, at the southeast corner of I-15 and SR-138. It went up in 1917 to honor pioneers who used the trail in 1849.

What is the Mormon Rocks Interpretive Trail like?

Here is what Forest Service materials say about trail 6W04:

• Length: about a 1-mile loop (1.03 miles) on the trail page, last updated January 2026. The older district brochure says 3/4 mile.
• Difficulty: easy on the trail page; easy to moderate in the brochure.
• Surface: mostly bare ground. The brochure mentions a small footbridge near the start.
• Views: the trail page promises views of the rocks and the Cajon Pass. The brochure names Cajon Summit, Ralston Peak and the Cucamonga Wilderness.
• Wildlife: look for swifts, hawks, ravens and coast horned lizards. The trail page also warns of rattlesnakes, bears and mountain lions.
• Dogs: must be on a leash of 6 feet or less.
• Facilities: the trail page does not list restrooms or drinking water, so bring your own.

A Forest Service engine crew built the trail in 1975. The trail page says interpretive brochures may be available at the trailhead or the Lytle Creek Ranger Station.

What is the Mormon Rocks fire station?

It is a working San Bernardino National Forest fire station on Highway 138 and the trailhead parking area. A Forest Service review notes it often serves as an incident command post.

The Blue Cut Fire started on August 16, 2016, east of Highway 138. As it reached the station, a fire whirl crossed the only driveway out, and crews moved members of the public into crew vehicles until it passed. The event is now a learning case study. Because the station is active, keep the driveway clear.

Do you need an Adventure Pass at Mormon Rocks?

No, not for the fire station lot. The trail page says parking there costs nothing. The district brochure says you do not need an Adventure Pass to park at the station.

Other San Bernardino National Forest day-use sites with amenities do charge. As of November 2026, an Adventure Pass is $5 a day or $30 a year and works on the Angeles, Cleveland, Los Padres and San Bernardino National Forests.

Are there closures at Mormon Rocks in 2025 or 2026?

As of November 2, 2026, no alert on the San Bernardino National Forest alerts page names Mormon Rocks, the Cajon Pass or Highway 138. A July 29, 2026 road closure order covers parts of the Front Country Ranger District, so check it before you drive forest roads. Forest-wide fire restrictions began June 9, 2026: fires are allowed only in Forest Service rings or grills in listed areas. The Lytle Creek - Wrightwood fire danger rating was High.

Highway 138 itself can close. After rain on Christmas Eve 2025, the CHP said SR-138 was closed because of heavy flooding and a partly washed-out road, Victor Valley News reported. The closed segments ran from I-15 to Summit Valley Road and, on the Phelan side, from SR-2 to Cajon Boulevard. We did not find an official reopening date for the Phelan side. A separate short closure on April 14, 2026, on the Hesperia side of the pass, lifted the same afternoon.

Before you go, check Caltrans Road Information for SR-138, or call 1-800-427-7623. For the bigger freeway picture, see our Cajon Pass I-15 update.

Can you watch trains from Mormon Rocks?

Yes. The NPS notes that SR-138 runs up Horsethief Canyon, and that BNSF and Union Pacific tracks share the pass.

The Forest Service's Summit Scenic Overlook page explains the lines. BNSF added a third main track in summer 2008. Union Pacific uses the former Southern Pacific Palmdale cutoff, which opened in 1967. Amtrak's Southwest Chief also crosses the pass. The overlook, on Highway 138 west of Summit Valley Road, draws many railfans.

Watch only from public land, turnouts and roads. Railroad tracks and right-of-way are private property. The Forest Service asks railfans to report suspicious activity to BNSF at 1-800-832-5452. See also the BNSF Barstow International Gateway.

Tips for photographing the Mormon Rocks

• Light: low sun early or late in the day brings out texture and warm color in the sandstone. Midday light tends to flatten the slabs.
• Season: cooler months are more comfortable for the hike. In summer, go early and carry water.
• Angles: the trail vista gives the classic view of the tilted beds. Stop only at legal turnouts.
• Trains: a train passing below the cliffs makes a strong frame. Use a longer lens and stay well back from the tracks.

For more forest outings, see mountain day trips from the High Desert and Deep Creek Hot Springs.

How Pleasant Hill can help

If you are thinking about buying or selling near the Cajon Pass, you can search homes, request a free home valuation, or reach Nancy Navarro in our Hesperia office. You can also contact us with any question.

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