I'm visiting Orlando, and my girlfriend told me that the reason so many of the streets in Florida are paved with bricks is because they used as ballast in ships, and when they were no longer needed they would repurpose them as pavement.
Immediately I thought of a story I used to tell my guests when I was a tour guide in the Pike Place Market in Seattle. The large stones used as cobbles in lower Post Alley are supposedly ballast stones as well. They say that ships would arrive empty from San Francisco and drop off their stones so they could fill up with timber. The story in Seattle further goes on to suggest that those ballast stones were rubble from the 1906 earthquake.
Most of the Seattle version sounds fanciful, and there's a strong chance it came from Bill Spiedel, who is well known for playing fast and loose with history in order to tell a good story, but since I heard something similar on the other side of the country it made me wonder if there was perhaps a kernel of truth.
I posted this about a year ago and got no response, so after stumbling across it i decided to try again. Thanks!
I haven't heard of this, however I would ask about the size of the stones. The the images of wrecks underwater that I saw while studying maritime archaeology had ballast stones that were huge - much, much larger than cobblestone sized.
However, it worth nothing that the ballast could itself be considered part of the cargo, if the stone is of any value. The weight of stone would be much heavier than wood, so simply swopping them over s unlikely. That's not to say it never happened, or that part of the ballast was replaced to make way for high value goods.