Saturday, October 12, 2013
The elegant barrier beach that separates Esquimault Lagoon from the Strait of Juan de Fuca is called the Coburg Peninsula and I guess that technically, it is a peninsula, but most of us would just call it a spit. (And anyway, there is a much larger and very different Cobourg Peninsula in Australia's NT. It's not a spit).
Apparently, as the glacier retreated 15,000 or so years ago, it drained through this valley and in the process it built the large Colwood Delta. The big Metchosin gravel pit is visible above the south end of the beach, although it shut down in 2007-2008 and is now slated for redevelopment.
But long before the mine, gravel had eroded from those bluffs and been transported by waves northward across the mouth of the lagoon to form the spit. The tidal inlet has been pushed up to the northernmost end of the beach, where it presses against the bedrock headland at Fort Rodd Hill.
Google Maps: AERIAL VIEW
The lagoon is large enough to allow some wave action and there are beaches on the inside of the spit as well as on the outside, although they look very different, and may also be strongly influenced by tidal currents near the inlet.
There are reports online suggesting that this relatively coarse-grained beach may have been wider and sandier during the peak of mining operations, since much of this finer material would have been spilled (either during barge loading or simply wasted because I believe gravel is the really high demand component for aggregate producers)
This is a similar story to the one we hear about the beach at Sunset Beach and Day Island in Tacoma (University Place), when the large Chambers Creek gravel operations were active. Its funny how usually the affect of human activity is to restrict sources of sediment, but these big gravel mines actually did just the opposite - especially in the old days when they operations were sloppy and an awful lot of sand was just dumped onto the beach.