'Torrents of Mud', 1849.
© Science Museum / Science & Society Picture Library
Colour engraving by Josiah Wood Whymper taken from 'Phenomena of Nature', published in London in 1849 for the Society for Promoting Christian Knowledge. 'In the higher receses of mountain regions, melting glaciers can result in the softening of immense beds of clay on which many rocks are found to rest. From such a softening can arise the land-slips, inundations, avalanches and torrents to which mountain valleys and villages are liable.'