Channels and minerals

Send us Fan Mail Time to descend into and out of one of the classic components of this frontier landscape - one of the "gaps". You have already experienced a few and today there will be a few more. But your legs need a break so we are going to deviate south of the Wall too. To see a ditch, then go find about two mineral resources that were used extensively by the Romans - coal and iron - but what do we know about them.