Dec 15

Dec 15 Geology of Coastal Dunes in Oregon and California

Coastal Sand Dunes

We tend to think of sand dunes as a desert phenomenon, but did you know sand dunes are also found at the coast?

Dune Formation

Coastal sand dunes are basically pieces of inland mountains that have been worn away by time and weather and washed downstream toward the ocean. When the sand reaches the ocean, it is pushed back inland by tides, waves, and wind. In the portions of the coast that have gentle slopes, the sand spreads out from the entry point (the end of the river that carried it) and piles up into dunes.

Sand-Loving Vegetation

One of the ways that the dunes are held in place is the growth of plants such as beach saltbush. Other small plants with long, low-lying stems creep along the surface while their taproots hold them in place. These plants are usually succulent to hold water and hairy to protect them from intense sunlight. In a way, the vegetation is not that different from what can be found in desert sand dunes. Even salt-tolerance, which may not be so obvious, is a feature of some desert plants that grow along the edges of dry lakebed such as Soda Dry Lake, which I described in my post about water in the desert.

Where to Enjoy the Dunes

In California, perhaps the most popular and the most wide-spread dunes are at Oceano Dunes State Vehicular Recreation Area in the area of Pismo Beach. The dunes are open to dune buggies and ATVs. Or, a few miles south the Guadalupe-Nipomo Dunes National Wildlife Refuge is accessible only by a fairly long walk. The beauty of mostly-undisturbed dunes with native vegetation may be worth the effort to you. Lots of campgrounds in Pismo Beach afford easy access to the dunes. Other locations include the stretch from Malibu to Ventura, Fort Ord Dunes and Marina Dunes near Monterey, and Bodega Dunes in Bodega Bay. We like to camp at Doran Regional Park when we are in that area.

The Buster Keaton movie “Seven Chances” includes a wonderful chase scene in the dunes of Los Angeles. I found a GIF here. Most of the dunes in this area have been developed, with just a small park in Manhattan Beach left open to the public.

The LAX Dunes, adjacent to Los Angeles Airport (LAX), have been undergoing restoration. In the 1920s the area was developed with houses, but the noise of LAX chased most people away and the city took over the property. Now, a few concrete foundations can be found but most of the homes, streets, and non-native vegetation were removed. In the early 1990s restoration began with the introduction of the El Segundo Blue Butterfly. In 2013 The Bay Foundation started active restoration of the 302 acres.

The state of Oregon has a great website to help you plan your dune adventure:

https://traveloregon.com/things-to-do/destinations/parks-forests-wildlife-areas/a-locals-guide-to-the-oregon-dunes/