Quoting from www.birmingham.ac.uk/facilities/lapworth-museum/about/lapworth
Lapworth recognised the importance of the graptolite fossils within the rocks of the Southern Uplands, and how they could be used to zone and correlate the sequences across the area. He realised that in order to record individual rock units, and associated graptolite biozones, the area had to be mapped in great detail. He pioneered the use of detailed, large-scale geological mapping, which proved vital for the interpretation of the geological structure and history of the region. His work resulted in the Geological Survey having to re-map and re-interpret the entire area, and producing in 1899 the great Memoir on the Geology of the Southern Uplands of Scotland which has been described as 'a monument of the man [Lapworth] who made it possible'.