Mendip Hills In some areas the limestone and the dolomitic conglomerate have been mineralised with lead and zinc ores. From the time of Roman Britain until 1908, the hills were an important source of lead. These areas were the centre of a major mining industry in the past and this is reflected in areas of contaminated rough ground known locally as "gruffy". The word "gruffy" is thought to derive from the grooves that were formed where the lead ore was extracted from veins near the surface. Other commodities obtained included calamine (zinc ore), manganese, iron, copper and baryte. The eastern area reaches
Francis Metallic Surfboat Francis Metallic Surfboat The Francis Metallic Surfboat is a boat, currently housed at 130 West Center Street in Douglas, Michigan. It was listed on the National Register of Historic Places in 2015. It is one of two known surviving examples of its kind, one of the first type of coastal rescue craft used. The Francis Metallic Surfboat was designed by Joseph Francis, an inventor who specialized in inventing and constructing maritime lifesaving equipment. Francis constructed 137 of these vessels from about 1849 to 1857, of which 48 were used on the Great Lakes. This particular boat dates from approximately 1854,