Malapai Hill, Mountain summit in Joshua Tree National Park, California, United States

Malapai Hill is a small mountain in Joshua Tree National Park with two summits, the true summit on the north, rising to 1,304 metres. It is made of aphanitic alkaline olivine basalt with olivine phenocrysts, and its steep slopes carry piles of monzogranite and basalt talus. Lherzolite xenoliths are abundant in the rock.

The formation took shape roughly 15.93 million years ago when magma cooled within ancient granite rocks. This ancient process created the structure visible today.

The name comes from Spanish and refers to the rough, broken terrain created by volcanic rock formations. Today visitors can still see how this description fits the jagged landscape that defines the area.

Compass navigation can be affected by magnetite deposits in the area, so GPS devices are more reliable for finding your way. Visitors should bring digital devices rather than relying solely on traditional compasses.

The dark basalt carries abundant lherzolite nodules, chunks of depleted mantle from the zone of partial melting that fed the magma. Rarer pieces of White Tank monzogranite are also embedded in the rock. Geologists read these inclusions as samples of material normally far below the surface.