Like many coastal communities, Fort Bragg used to toss much of its garbage over the edge. Folks don't do it anymore, but the legacy remains in the form of Glass Beach on the north end of town, where a little coagulated metal and a lot of ground up glass mark the old dump site. Glass is actually a very successful substitute for natural beach sand - since it's basically the same thing (silica, even if not quartz).
There are many glass beaches - some accidental, some more purposeful. There's another one much like this on Kauai in Hanapepe (Ele'elu 2008). And a more subtle one at Cornwall Beach in Bellingham (2006). For that matter, my first full post in this blog, back in December 2005, was also titled Glass Beach, albeit one near Port Townsend (and no pictures of glass - maybe I should go back and revisit that one).