Mt Baldy Village. There are no roads or maintained trails connecting the mountain to the less populated region to its north, but a use trail leads over Dawson and Pine Mountains to Wright Mountain and the Pacific Crest Trail, overlooking the town of Wrightwood. Climate A weather station located around 7,700 feet was run during the 1960s; it recorded an average of 131 inches of snow per year. Snow peaks late in the season; in April 1967, 120 inches of snow fell. Natural history Geology Mount San Antonio lies in the front range of the San Gabriel Mountains, one of the Transverse Ranges of Southern California, formed around the San Andreas Fault system. The Transverse Ranges were formed because of a dog-leg bend in the San Andreas, which is a transform fault. The bend makes it difficult for the two plates to move smoothly past one another, and mountains were raised as a result. The prehistoric Hog Back landslide lies in the canyon of San Antonio Creek at 4000' elevation. When the slide occurred, it dammed the river, whose depth built up until the water was released catastrophically, forming a slot canyon which now holds some of the area's few good rock climbing routes (difficulty 5.11, sport). In modern times, notable floods have occurred in 1938 and 1969. The San Antonio Dam was completed in 1956, after a pause due to World War II, in an effort to prevent future floods as severe as the one in 1938, which damaged the low-elevation, highly populated areas below. The dam succeeded in significantly reducing the damage done by the 1969 flood. Hydroelectric plants along San Antonio Creek are tied to the electric grid. Plants The lower land area of the mountain consists of an ecological community known as yellow pine forest. Tree species include lodgepole pine, Jeffrey pine (also known as western yellow pine), white fir, and some sugar pine. These forests are fairly sparse, and are intermixed with chaparral and oak savannah. Higher up, the yellow pine forest community gives way to a pure lodgepole forest. Near 9,000 ft (2,750 m) these become increasingly krummholzed, and beyond about 9,500 ft (2,900 m) lies an unforested alpine zone. Mountain mahogany trees grow on the slopes above San Antonio Creek. The dominant shrubs at the higher elevations are manzanita and bush chinquapin. As the elevation increases, there is a higher ratio of chinquapin