The erosion information presented on the coastal erosion maps is placed in a geologic context on twenty-six coastal geology maps using the same bases as the coastal erosion maps. The geology maps generalize coastal morphology and geology by means of schematic cross sections. Natural coastal processes such as cliff erosion, slope failure, wave erosion, landslides, block falls, debris slides, and cave collapse are illustrated diagrammatically on the cross sections. Ultimately, wave erosion is the primary or initiating erosive process along the San Mateo County coast. Waves erode the base of the sea cliffs or coastal bluffs, thus oversteepening and destabilizing the slopes above. Landslides, debris slides, and block falls are secondary erosive agents that move loosened rock material down the slopes to the beaches below, where the material is eventually eroded away by wave activity. Along most of the San Mateo County coast groundwater that seeps from the cliff face softens and loosens even otherwise resistent bedrock material, thus contributing to the erosional process.
1: Thornton Beach
2: Mussel Rock
3: Sharp Park
4: Mori Point
5: Point San Pedro
6: Devils Slide
7: Point Montara
8: Seal Cove
9: Pillar Point
10: Miramar
11: Half Moon Bay
12: Miramontes Point
13: Eel Rock
14: Seal Rock
15: Martins Beach
16: Tunitas Creek
17: San Gregorio Beach
18: Pomponio Beach
19: Pescadero Beach
20: Pebble Beach
21: Bolsa Point
22: Pigeon Point
23: Franklin Point North
24: Franklin Point South
25: Point Año Nuevo
26: Año Nuevo Creek