Blacklock was born in London, the son of a bookseller who originated from Cumwhitton in Cumberland. Returning to Cumwhitton at the age of four, Blacklock began his career as an apprentice engraver and lithographer to the Carlisle bookseller and printer Charles Thurnham. By 1836 he was exhibiting in London, where his oil paintings and watercolours attracted the attention of many artists and critics, including J. M. W. Turner and John Ruskin. Deteriorating health drove Blacklock back to Cumberland in 1850 and soon forced him to give up painting. This late work was painted during a period of remission in his illness. The highly detailed portrayal of the mountainside and vegetation reveals the influence of the Pre-Raphaelite painters, such as William Holman Hunt and Dante Gabriel Rossetti.