AT the eighteenth session of the International Geological Congress, held in London last summer, after being postponed from 1940, the proceedings of Section F were devoted to a consideration of the geology, paragenesis and reserves of the ores of lead and zinc. Up to the time of the Second World War, it had been assumed generally that resources of these base metals, while not inexhaustible, would be sufficient for many generations, even though the rate of annual world production had risen from 200,000 long tons lead metal and 120,000 long tons zinc metal in 1860 to 900,000 and 500,000 tons respectively at the turn of the century, and had reached nearly 2,000,000 tons of each metal in 1939. The searching examinations of their mineral resources carried out by the belligerent countries during the War, coupled with an emphasis upon production rather than exploration and development during hostilities, led to the realization of an immediate shortage of both metals when the War ended, and to the expression of grave doubts as to the future position. The subject chosen for Section F was, therefore, of immediate practical interest in 1948.