Sunday, October 13, 2013

French Beach

The south coast of Vancouver Island from Sooke west to Port Renfrew forms the northern shore of the Strait of Juan de Fuca. This is a rocky coastline, with the Metchosin Igneous Complex dominating the coast from Sooke Harbor to Sombrio Point, and Leech River metamorphics farther west. Less deformed Tertiary sediments overlay them in places, and of course, there is often glacial stuff on top. But the bottom line is that the coast consists mainly of rocky headlands, cliffs, and platforms, and beaches are a little hit and miss.

Google Maps:  AERIAL VIEW

Where there are beaches, they tend to occur where the orientation of the coastline shifts southward allowing the formation of pockets turned to collect the dominant westerly waves.  This is the case with French Beach, but also with China Beach and Sombrio Beach, which I'll get to later.  These beaches are all different, although my brief excursion left me with far more questions about the reasons for these differences than answers.  Some of it is about the abundance and type of sediment available, some is related to the presence of streams, some is related to the nature of nearshore bathymetry, and so on.

I camped at French Beach, which meant I got to see it morning and evening.  It was relatively steep and gravelly, or at least it was last weekend, with nicely defined cusps. If there was much sand, it was pretty low on the beach face (and tides don't get very low this time of year).

One thing that intrigued me at French Beach (at China Beach as well), was the broad forested terrace (maybe not the right word) behind the beach - the actual bluff was many hundreds of feet landward.  This suggests that either the beach has built seaward over time or that the coastline has experienced uplift (the latter can contribute to the former), although the story is inevitably much more complicated.

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