Hi, can you possibly link or name the maps you are referring to? I an curious to look at it, but without stating point I can't really research much. I can say that around the area you are referring to there is still very much a bay - the Bay of Cadiz, near which there is the river Guadalquivir which in Roman times was called exactly Beatis all of which corresponds to your description. If you can give the exact maps you are looking at, it could be doublechecked