Then we obſerve the Frets in the Banks of Rivers that are newly made by any great Land-Flood, which uſually are then very clean, to ſee, if happily we can diſcover any metalline Stones in the Sides and Bottoms thereof, together with the Caſt of the Country (i.e. any earth of a different colour from the reſt of the Bank), which is a great help to direct us, which ſide or hill to ſearch into.