Amboy Crater National Natural Landmark

Amboy Crater is a textbook cinder cone — a relatively small, steep-sided volcanic feature formed by the accumulation of cinder, scoria, and ash ejected during explosive but relatively short-duration volcanic eruptions. Unlike the substantially larger composite volcanoes (Mount Shasta, Mount Rainier) or the massive shield volcanoes (Mauna Loa, Mauna Kea), cinder cones typically form during a single eruptive episode lasting weeks to years, after which the volcano is permanently extinct. Amboy Crater is among the youngest such features in the lower 48 states; the principal cone-building eruption is dated to approximately 79,000 years ago, with a less substantial secondary eruption approximately 6,000 years ago.

The Amboy Lava Field surrounding the crater extends approximately 70 square kilometers and represents the cumulative output of all the volcanic activity at the site. The dominant lava type is basalt — the fluid, low-silica volcanic rock that produces the characteristic black surfaces, the ropy pahoehoe textures (smooth surfaces where the lava flowed freely), the rougher aa textures (where the surface broke up during flow), and the various lava tubes (subterranean channels where flowing lava drained out, leaving hollow conduits that sometimes collapsed to form visible features). The lava field is one of the largest and most accessible volcanic landscapes in California.

The crater's exceptionally good preservation — the distinct cone shape, the visible breach in the western rim (formed during a late-stage lava flow that drained from the crater), the well-defined crater floor — reflects both the youth of the feature (insufficient time for erosion to substantially modify the shape) and the arid Mojave climate (limited precipitation reduces the erosion rate). Crater forms in wetter climates typically erode rapidly; the Mojave's desert environment has preserved Amboy Crater in something close to its original eruption-aftermath condition.

The hike begins at the small parking lot off National Trails Highway about three miles west of Roy's Motel. The parking area includes interpretive signage describing the volcanic geology, basic restroom facilities (vault toilets), no water (bring your own; the desert hike requires substantial water especially in warmer months), and trail-head information. The 1.5-mile one-way trail (3 miles round-trip) is well-marked with cairns, posts, and BLM signage; the route is largely intuitive on the broad lava field surface.

The trail leads east-northeast from the parking lot across the lava field, providing close-up views of the various volcanic features — the ropy pahoehoe surfaces, the rougher aa textures, the collapsed lava tubes, and the various volcanic bombs scattered across the surface. The walking surface is generally flat and broad, though the rocky lava terrain requires sturdy footwear; running shoes are inadequate for the surface. The trail circles around the south side of the cone and approaches the rim from the southwest through the natural breach in the crater wall.

The final climb to the rim through the breach is the most challenging section — approximately 250 feet of elevation gain across a half-mile, on a steeper rocky surface. Most hikers in reasonable condition manage the climb without difficulty; the reward is the crater interior and the spectacular rim view. Hikers can walk down onto the crater floor through the breach (the floor is flat and accessible) and then climb to the highest points on the rim for the panoramic view. The total hike time for the round-trip with appropriate exploration at the crater is about 2 to 3 hours.

The Mojave's extreme summer climate makes timing critical. Daytime temperatures from June through September regularly exceed 110°F; the dark basaltic lava surface absorbs solar heat and the lava field surface temperature can exceed 140°F in summer afternoons. Summer hiking at Amboy Crater is genuinely dangerous; heat exhaustion and heat stroke are real risks. October through April provides comfortable hiking conditions; spring (March, April) and fall (October, November) are optimal with daytime highs in the 70s and 80s.

Even in optimal weather, the hike requires preparation. Water — minimum two liters per person for the round-trip, more in warmer conditions — is essential; there is no water source on the trail. Sturdy hiking shoes or boots are required; the lava surface is rough on inadequate footwear. Sun protection (hat, sunscreen, sunglasses) is essential year-round. A trail map (available at the parking lot and online from the BLM) is useful but not essential for the well-marked route. Cellular service is unreliable; do not depend on phone communication for emergency support.

The site is administered by the Bureau of Land Management's Needles Field Office. There is no entrance fee, no permit required, and no advance reservation necessary. The site is open daily from dawn to dusk; overnight camping is not permitted at the immediate site. Combined visits with Roy's Motel (three miles east) and the broader Amboy area work well; the crater hike and the Roy's visit together fill a half-day. Travelers continuing west from Amboy along Route 66 toward Ludlow and Newberry Springs can combine the crater hike with the larger desert Mother Road driving experience.