My Dad is going to give a talk on the history of boat building. I was asking him how developments in materials had affected the sort of boat that could be built. I asked, in particular, whether the advent of iron had changed boat design, thinking of boats built of metal.
He told me that the Vikings had used iron nails in their boats. I was amazed. I was even more amazed to learn where the iron had come from in some cases. The Vikings made it to Newfoundland, forced back only when crops failed in Greenland. Remains of early settlement there show that iron was made out of the orange deposits found in puddles.
Truly. “Bog iron” it is called. Iron bearing ground water oxidises once it reaches the surface. The orange deposits are refined, and made into iron.
“In the bog, the iron is concentrated by two processes. The bog environment is acidic, with a low concentration of dissolved oxygen. In the acidic environment of the bog, a chemical reaction forms insoluble iron compounds which precipitate out. But more importantly, anaerobic bacteria (Gallionella and Leptothrix) growing under the surface of the bog concentrate the iron as part of their life processes. Their presence can be detected on the surface by the iridescent oily film they leave on the water (left), another sure sign of bog iron. In Iceland (right), the film is called jarnbrák (iron slick).”