Lost Horse Mine Trail                                                                      

See much of the variety of Proterozoic gneissic rocks found in Joshua Tree National Park

Map Keys View 7.5'

Trail Length 4.5 miles, ~3 hours

Elevation Change +700 feet

Difficulty moderate

Directions Trailhead at the end of road to Lost Horse Mine, 1.1 miles from intersection with

                    Keys View Road

Description The trail begins in ancient metamorphic rocks typical of the central province of the Park. These gneisses form the banded dark and light mountain slopes of the Lost Horse Mountains visible from Queen Valley and Paradise Valley. At the trailhead, the metamorphic rocks are composed of interlayered mica-rich gneiss and black amphibolite. These rocks probably formed from metamorphism of still more ancient rocks formed on the floor of an ancient sea, including clay-rich sediments now metamorphosed to mica-rich gneiss, and basalt now metamorphosed to black amphibolite. The trail climbs slowly eastward up into the Lost Horse Mountains, through well exposed mica-rich gneisses. As you climb, notice that the gneisses display evidence of strong deformation, in the form of tight folding of the compositional layers. After about 1/3 of a mile, the trail crosses a small stream. The streambed is littered with fragments of dark basalt, eroded from the small hill to the north of the trail. This hill is capped with Miocene(?) - Pliocene(?) alkali basalt. Beyond the stream, the trail continues to climb through a variety of gneisses with well-developed folds, including mica-rich gneisss and amphibolite, as well as more homogeneous grey gneiss. As you approach the mine, notice that the ridgeline is composed of a much lighter rock, which is a very light tan granitic gneiss. The parent rock of this gneiss probably formed as a granite intruded into the mica-rich gneisses. The Lost Horse Mine was constructed to extract gold from west-trending, steeply-dipping quartz veins that cut across the gneisses of the Lost Horse Mountains. Return to the trailhead the same way you came.

Touch an image to learn more about rocks and geology along this trail.