"Geology Factsheet"(PDF). Lake District National Park Authority, Education Service. p. 3. Archived from the original(pdf) on 21 October 2019. Retrieved 1 September 2012.
"Geology Factsheet"(PDF). Lake District National Park Authority, Education Service. p. 3. Archived from the original(pdf) on 21 October 2019. Retrieved 1 September 2012.