One of Murchison's earliest reforms was to introduce sheet memoirs, or explanations to accompany individual one-inch geological maps. 'The first memoir in this series was: The geology of the country around Cheltenham, (Sheet 44). This series covers the 'Old Series' numbering. The series continues to the present day in the 'New Series' Sheet memoirs and the 1:50,000 sheet description and sheet explanation sub series.