The steepest and most spectacular crags and mountains of the central Lake District are nearly all of volcanic origin and represent the much eroded remnant of an ancient volcano active 450 million years ago during the Ordovician Period (figures 1 and 2). At this time Earth would have been unrecognisable to us; indeed it must have been like a distant planet from a far galaxy with the land masses completely devoid of life it was still to be 100 million years before land plants became established. Moreover the shapes and positions of oceans and continents were entirely different from those of today. These conclusions are made possible by the great variety and detail of research in the geological sciences, which is increasing enormously year by year. This work has included the laboratory examination of rocks, numerous specimens of which have been inspected under the microscope and chemically analysed, so permitting comparisons to be made with similar rocks being formed at the present time. Studies of marine fossils from
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