'Perforated Rocks', 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. 'The powerful action of the sea upon rocks and cliffs is displayed in various ways. When the rocks are of limestone or such comparatively soft material, they are often worn and perforated into a variety of remarkable forms. The wearing action of the waves is chiefly upon a space marked by the rise of the tide and is greatest at the mean level of the sea.'