The Santa Rosa and San Jacinto Mountains trend northwest-southeast along the southwestern edge of the Colorado Desert Geomorphic Province. The Santa Rosa and San Jacinto Mountains themselves are part of the Peninsular Range Province which consists of a chain of mountains beginning with the northernmost San Jacinto Mountain, and trending southward through southern California into Baja California, Mexico. The Santa Rosa and San Jacinto Mountains consist largely of pre-late Cretaceous meta-sedimentary and meta-volcanic rocks that have been intruded by late Cretaceous age plutonic rocks, largely of granitic composition.
The Coachella Valley, part of the Colorado Desert with elevations ranging from less than mean sea level to several hundred feet, is nestled against the steep slopes of the Santa Rosa and San Jacinto Mountains. The San Andreas Fault itself runs parallel to the mountains on the other side of the Coachella Valley; however there are faults along the base of the San Jacinto and Santa Rosa Mountains which are all part of the San Andreas Fault System.
San Jacinto Mountain is the highest point along the Peninsular Range Province, rising to an elevation of 10,805 feet above mean sea level as the result of fault block activity. Down below in the Coachella Valley, elevations range from below mean sea level to several hundred feet, resulting in an abrupt vertical relief of more than 10,000 feet on the steep eastern face of San Jacinto Mountain, and exceeding the vertical relief in most other parts of the contiguous United States except Death Valley.
The loftiness of the mountain captures significant amounts of rain and snow which makes the Coachella Valley a garden spot in an otherwise dry desert region. As water becomes a more scarce resource with the burgeoning southern California population, it will become critical to maintain the watershed afforded by the San Jacinto and Santa Rosa Mountains. Development and activities which can contaminate the water resources need to be kept to a minimum.
San Jacinto Mountain is home to the Palm Springs Aerial Tramway, which takes visitors by cable car from the desert up 6,000 feet to alpine forests in 15 minutes. The top of San Jacinto Mountain is managed by the Mount San Jacinto State Park and Wilderness. In the winter, visitors leave the balmy desert to cross-country ski on top of San Jacinto Mountain. In the summer, visitors escape the oppressive heat to hike in temperate alpine forests.
The spectacular vertical relief, the need to protect the watersheds, and the many recreation opportunities afforded by San Jacinto Mountain make it worthy of national recognition.
Natural Hot Springs and Palm Oases. The Palm Canyon Fault which runs along the base of San Jacinto Mountain is part of the San Andreas Fault System. The faults dam ground water which is then forced up to the surface. In the desert, native fan palm oases (Washingtonia filifera) and cottonwood/willow riparian areas form where there is surface water, providing a critically needed source of food and water for desert wildlife, and delightful places for humans to visit. These areas provide dramatic contrast to the hot, dry desert environment.
The Indian Canyons, located at the base of San Jacinto Mountain and managed by the Agua Caliente Band of Cahuilla Indians, boasts the largest system of native fan palm oases in the United States. Visitors from around the world come to visit these spectacular oases nestled in steep rocky canyons where the force of running water over the millennia have carved the rocks into curvaceous pools and waterfalls. Higher up the canyon walls, the rocks sheen with the beautiful patina of desert varnish.
Associated with some of the springs along the base of the San Jacinto Mountains is hot mineral water, heated at depth probably by emanating gases and hydrothermal activity associated with the San Andreas Fault zone. This hot mineral water is of excellent quality, and is available to visitors at world-class spas throughout the Coachella Valley. Conservation and protection of the watershed which recharges these natural springs is important to maintain the high quality of water in the Coachella Valley, and to continue supporting the tourism industry which utilizes this resource.