9.5: South Coast

The South Coast is a region of California, making up roughly the southernmost third of the Californian coast. It refers for the most part to the Southern California coastal counties of Ventura, Los Angeles, Orange, and San Diego due to the cosmopolitan "SoCal" atmosphere and location of major urban coastal centers. Of these counties only the western two-thirds of San Diego, coastal half of Ventura, most of Los Angeles and all of Orange are included.

Geologists consider the northern Channel Islands to be a westward extension of the Santa Monica’s into the Pacific Ocean. The range was created by repeated episodes of uplifting and submergence by the Raymond Fault, which created complex layers of sedimentary rock, some containing fossils of invertebrates and fish. Volcanic intrusions have been exposed, including the poorly named andesitic. "Sandstone Peak", which is the highest point in the range at 3,111 feet (948 m). Malibu Creek, which eroded its own channel while the mountains were slowly uplifted, bisects the mountain range.

However, some sources include the western part of Riverside, and southwestern part of San Bernardino Counties, and the northwestern corner of Baja California, because of their proximity to the Pacific Coast and because they are in the same bio-region and watershed.

Figure 9.9: Location of the South Coast in California. Map of the South Coast region of California by Wikimedia User Cristiano Tomás is used under a CC BY-SA 4.0 license.

Physical Geography

The Peninsular Ranges are a group of mountain ranges in the Pacific Coast Ranges, which stretch over 900 miles from southern California in the United States to the southern tip of Mexico's Baja California peninsula. They are part of the North American Coast Ranges that run along the Pacific coast from Alaska to Mexico. Elevations range from 500 ft to 11,500 ft (150 m to 3,500 m) and vegetation in these ranges varies from coastal sage scrub to chaparral, and from oak woodland to conifer forest.

The Peninsular Ranges of southern California include the Santa Ana Mountains, Santa Monica Mountains, San Jacinto Mountains, and the Laguna Mountains. The Peninsular Ranges of Baja California include the Sierra Juarez, Sierra San Pedro Martir, Sierra de la Giganta, and Sierra de la Laguna. These ranges run from north to south.

The Santa Ana Mountains are the largest natural landscape along the coast of southern California. These mountains peak at about 5,689 feet, on Santiago Peak. This range starts in the north, in the Corona area heading southeast of the Puente Hills region.

The Santa Monica Mountains are approximately 40 miles (64 km) east-west from the Hollywood Hills in Los Angeles to Point Mugu in Ventura County. The western mountains, separating the Conejo Valley from Malibu, suddenly end at Mugu Peak as the rugged, nearly impassible shoreline gives way to tidal lagoons and coastal sand dunes of the alluvial Oxnard Plain. The mountain range contributed to the isolation of this vast coastal plain before regular transportation routes reached western Ventura County. The eastern mountains form a barrier between the San Fernando Valley and the Los Angeles Basin, separating "the Valley" on the north and west-central Los Angeles on the south. The Santa Monica Mountains are parallel to the Santa Susana Mountains, which are located directly north of the mountains across the San Fernando Valley.

The San Jacinto Mountains are in the desert areas in the north and east side of southern California. They peak at about 10,833 feet. They run from the San Bernardino Mountains southeast to the Santa Rosa Mountains. This mountain range is the northernmost part of the Peninsular Range.

The Santa Rosa Mountains are located at the southern end of the San Jacinto Mountains, where they connect to it. The range extends for approximately 30 miles (48 km) through Riverside, San Diego and Imperial counties, along the western side of the Coachella Valley, where they bound the Anza-Borrego portion of the Colorado Desert. The highest peak in the range is Toro Peak (8,717 feet).

The Laguna Mountains are in the eastern part of San Diego County. They range northwest to southeast for approximately 20 miles and peak at Cuyapaipe Mountain (6,378 feet). These mountains extend northwest about 35 mi (56 km) from the Mexican border at the Sierra de Juárez. The Sonora Desert lies to the east and the Santa Rosa Mountains are to the northwest.

Case Study – Balboa Island

Millions of years ago, powerful geological forces shaped the landscape we see today. The relentless pounding of the Pacific Ocean and the deposition of sediment by the Santa Ana River gradually formed a submerged sandbar off the coast of Newport Beach. This underwater feature, continuously evolving under the influence of tides and currents, eventually emerged above the waterline sometime between 1825 and 1865 as a small mudflat, that was surrounded by swampland. This newly formed sandbar laid the foundation for what would become Balboa Island.

Around 1860, James McFadden, a prominent Newport Beach landowner, envisioned transforming the undeveloped sandbar into a vibrant resort destination. In the early 1900s, W.S. Collins, a real estate developer, saw the potential of McFadden's vision. He purchased a significant portion of the land and began dredging the harbor to create a channel and further define the island's shape. This period also saw the construction of the Pacific Electric Red Car line, connecting Balboa Island to Los Angeles and making it a more accessible getaway for city dwellers.

The early 20^th century marked a golden age for Balboa Island. The iconic Balboa Pavilion, originally built as a Victorian bathhouse, quickly transformed into a renowned entertainment venue, hosting dances, concerts, and other social gatherings. The construction of the Balboa Fun Zone, with its Ferris wheel, arcade games, and carnival atmosphere, further solidified the island's reputation as a premier leisure destination. The 1920s saw the development of unique "Nutcracker" houses, small, colorful cottages designed to maximize space. These charming dwellings remain a hallmark of the island's character.

Figure 9.10: Aerial Photo of Balboa Island, 1921. Image hosted on Wikimedia Commons in the public domain.

During World War II, the island played a vital role in the war effort. The Balboa Yacht Basin served as a training ground for the US Navy, and the island's residents proudly supported the war cause. Following the war, Balboa Island experienced continued growth and development, maintaining its status as a beloved seaside escape.