Southern California is separated from the rest of the state by the east-west trending Transverse Ranges, including the Tehachapi, which separate the Central Valley from the Mojave Desert. Urban Southern California intersperses the valleys between the Santa Susana Mountains, Santa Monica Mountains and San Gabriel Mountains, which range from the Pacific Coast, eastward over , to the San Bernardino Mountains, north of San Bernardino. The highest point of the range is Mount San Gorgonio at . The San Gabriel Mountains have Mount Wilson observatory, where the redshift was discovered in the 1920s.