Geologist John Playfair died - On this day in Scottish history

Scottish geologist John Playfair died on 20 July 1819 at the age of 71. Playfair was a friend of fellow geologist James Hutton and wrote Illustrations of the Huttonian Theory of the Earth, in which he presented Hutton's theories on how the earth was formed, adding his own theories. Playfair was one of the first scientists to work out that a river carves out its own valley and he was a regular contributor to the Edinburgh Review.

The Playfair family held several important positions in Scottish society in the 1800s, John Playfair's two brothers worked as an engineer and an architect and his nephew William Henry Playfair was also an architect and designed the monument to John Playfair, which is pictured here and stands on Edinburgh's Calton Hill.