King Tide - Exuberant wave(s) - 12-21-14
New Moon - King Tide (6.4') in El Granada, CA - just south of Pillar Point Harbor along Highway 1 - looking southeast. I went out early just to catch the King Tide here. There are a couple of initiatives afoot to document conditions at king tides, to help us understand what's in the offing with sea level rise.
I love that wave. Well, actually it's two waves - one that reflected off the bluff and another incoming wave … They met coming in and going out, and Pow!
I chose this spot on the coast because the breakwater for the harbor accelerated the erosion in this area and the highest tides can wreak havoc. Here the bluff is rapidly approaching Highway 1.
Coastlines naturally develop certain shapes and curves as ocean waves bend around obstacles, like headlands. The coastline weathers and erodes, and sand or other sediment moves along the coast in a process called longshore drift. A natural headland will maintain an equilibrium with a flow of sediment and its natural curve, but human intervention changes the sediment movement and the erosion patterns.
The breakwater around Pillar Point Harbor disrupted the natural path of waves refracting around Pillar point, which in turn has caused a new curve to evolve. At the same time the natural flow of sand along this part of the coast was disrupted and this area may be sand-starved. As a result energy that previously dissipated elsewhere gets focussed here. … The result? Accelerated coastal retreat.
This marine terrace appears to be unconsolidated mud, silt, and sand. It is surprisingly resistant to weathering from the waves. I haven't been down to touch it lately but today as the waves pounded it it was shiny with a surface that looked like wet clay. Since the sediment is rather fine, it likely was deposited in a lower-energy lagoon or estuary, rather than in a marine environment. Or perhaps a marine terrace was raised and overlain by sediment that built up after it became a wetland. [ Anderson, Sarna-Wojcicki and Sedlock called this material "a thin veneer of younger, unconsolidated sediment." p.90]
These shots were taken on an overcast, misty morning, with a camera that is giving me meter problems. So I apologize for the strange lighting and contrast.