We came across this curiosity in the Chron this a.m.: several generations worth of free-floating sediment, upon which several pieces of the SF Bay's ecosystem depends, has finally washed out to sea after first being introduced via Central Valley rivers during the Gold Rush. The mud cannons used by gold miners siphoned so many tons of mud that eventually settled in the bay, that it has apparently taken this long to disappear, say scientists. We're unclear of all the bad implications though, but it seems to have something to do with global warming and the ecosystem needing to adapt back to its pre-1849 days of lower sediment levels. Anyway, herein lies your historical aquatic educational moment for this Monday morning.