During the Thanksgiving break of 2015, Becky (my wife) and I had a chance to take the world famous Palm Springs Tram. This tramway is the largest rotating aerial tramway in the world. It was opened in 1963 as a way of getting from the floor of the Coachella Valley to near the top of San Jacinto Peak and was constructed in the rugged Chino Canyon.  The floor of the 5.5 m aerial tram cars rotates constantly, making two complete revolutions throughout the duration of the journey so that the passengers can see in all directions without moving.  I took a video for down-leg of the trip.

      The San Jacinto Mountains are right triangular in outline. The northern margin is along San Gorgonio Pass, the east face looks down on Palm Springs and the diagonal is San Jacinto Valley. The highest peak is Mount San Jacinto, at 3700 m. The Range is really a single mountain block uplifted along faults, with movement occurring through the Pleistocene. The major fault that created the block is the San Jacinto fault, slicing northwest-southeast along the topographic diagonal of the mountain mass. Branches of this fault zone also define several linear valleys in the upland areas, ranging in elevation from 500 m to 1400 m.  At the bottom of the tram the rise is to 1400 m within one horizontal mile. Pictured below, Becky is standing near to the top of Mount San Jacinto at 3400 m higher than the valley floor. (less than 7.3 horizontal kilometers distant). This scarp is one of the great mountain scarps of the world.

     Seen in the video below, the tram begin it’s steepest descent as it passes the vertical faces of the younger light-colored granitic rocks.   Between the lower station at 2,600 feet elevation and the top at 8,500 feet, one may see both of the important rock types. The darker metamorphic rock is abundant as the trip begins. As the tram begins its steepest ascent, the car passes the vertical faces of the younger light-colored granitic rocks.  The upper station area is situated on an excellent exposure of quartz diorite. The rock is coarse granular, whitish in color with a liberal sprinkling of dark mineral crystals. Quartz diorite is abundant in the higher elevations of many of the mountain ranges of the southern California batholith.

    As the video below indicates, the tram shallows on it’s descent and below that, a darker metamorphic rock is abundant. These older rocks are of uncertain age. That they were once sedimentary rocks is very likely, but metamorphism has obliterated the fossil record. It is thought the rocks are probably of early Paleozoic time, variously 250 to as much as 600 million years old. The metamorphic series is massively banded, gray in color where fresh but mahogany or rust colored where weathered. Well-developed foliation planes of interbedded and contorted layers of schist and white recrystallized limestone, often injected by bands of granitic rock are common. The banded structure of these old rocks is very striking to the eye. The layers are oriented north-south, and dip or tilt to the east about 35 degrees.  The large flat rock boulders have been weathered loose along their banding planes, and are seen as gigantic scales or plates on the mountain side . Viewed from the north end of the city, the profile of the mountain face in outline is a remarkable straight-edge inclined of 35 degrees.  Watch the video below to get an excellent view of these formations.