Devil's Slide Trail Natural Features
Rich and diverse underwater habitats offshore are home to small fishes, crustaceans and other tiny marine life. Harbor seals and northern elephant seals haul out on offshore rocks and local beaches. In fall, these waters host one of the largest seasonal populations of white sharks in the world.
Whales may be seen passing on their spring and fall migrations. Most commonly spotted are gray whales on their journey thousands of miles between winter birthing lagoons off Mexico and summer feeding grounds in the Arctic. A spout or splash will indicate the presence of a whale as close as 100 feet from shore.
Many birds live or migrate here: seabirds, such as pelicans, cormorants, and Common Mures; raptors, such as hawks, falcons and turkey vultures; and songbirds, such as Benwick’s Wren, Golden-crowned and Song Sparrows.
The Common Murres who nest in the rocks below the trail became acclimated to passing traffic on Highway 1, but the arrival of trail-users may frighten them. Fencing and native vegetation have been placed to hide hikers and visitors from the view of nesting Murres. Trail users should respect these boundaries.
For more information see the 2014 Annual Report for the Restoration and Monitoring of Common Murre Colonies in Central California (.pdf).
Devil's Slide, positioned between San Pedro Ridge and Montara Mountain, is about half a mile wide and extends 900 feet from the ridge top to the ocean. Millions of years of upward pressure have weakened the rock of these cliffs. Water trapped underground causes the weakened rock to move. At the same time, the pounding surf washes away the bottom of the slide.
Falling rock from the slide have repeatedly damaged the road, causing Highway 1 to be closed dozens of times since it opened in 1937. Landslides occur where the sedimentary rock has been thrust over the granitic rock, causing broken, weakened ground.
Walk the trail for a demonstration of coastal erosion geology. Notice how different the cliffs at the south end look compared to those at the north end. The weathered rock face to the south is the granitic rock of Montara Mountain, the same rock found in the Sierra Nevada Range. In contrast, the rough layers of sedimentary rock at the north end were once the ocean floor. Not quite as old as the Montara Mountain rock, these layers of shale and sandstone have been thrust up and folded, over millions of years, by forces deep within the earth.