Erosion

Erosion-mud slide
Erosion – mud slide
Mud plume nearshore
Mud plume nearshore at
Torrey Pines State Beach

Any land above sea level is being eroded by physical, chemical, and biological processes. Soils creep slowly downhill and sometimes slide rapidly. A good example of a slide in soil is just off the road near the entrance to the Reserve. Running water is the most important erosion agent in the Reserve. After a winter storm, a plume of mud and sand stains the ocean out from Peñasquitos Lagoon. Soil and rocks in the lagoon have been carried to sea to become new sand on our beaches. Dams on our rivers have reduced the sand washed down into the ocean and our beaches are starving for sand.

Even the small streams crossing the Reserve cut deep canyons in time. Just after a rain, they make muddy waterfalls at the beach cliffs. Rainwater also becomes slightly acidic by dissolving carbon dioxide from the air, then dissolves cementing minerals from rocks. Loose grains can be carried away by wind or water. Plants pry apart rocks with their roots.Lichens dissolve rocks with chemicals produced by the fungus part of the lichen. Animals burrow in soft rock to allow water to penetrate and erode.

Canyon of the Swifts
Canyon of the Swifts
Beach waterfall
Beach waterfall

 

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