Trade routes and merchant ships

[richsc]

I was looking at a book about amphora in Britain. If they didn't use the Atlantic route, the cargo would have to be shipped by river boat to a certain point, off loaded and sent by land, then reloaded on boat and down to the Channel; at that point, if the river boat wasn't good enough, the cargo would have to be off loaded and loaded again onto a more seaworth ship. Quite a lot of labor and chances for breakage. I have read though, that an amphora of wine was worth a slave in exchange, so the amphora had to be very valuable. <p></p><i></i>