Geological Survey of Great Britain (England and Wales) Great Britain. Ordnance Survey. Sheet 312 solid and drift. Geological Survey of Great Britain. North Decimal Degree 51.0167. South Decimal Degree 50.8333. East Decimal Degree -2.5000. West Decimal Degree -2.9167. In upper left margin: Ordnance Survey of Great Britain. Relief shown by contour interval and spot heights. Transverse Mercator projection. National grid system. "Original geological survey on the one-inch scale by H. W. Bristow, published as part of Sheet 18 Old Series in 1850; revised in 1871-72 by H. W. Bristow, et al republished 1875. Resurveyed on the six-inch scale between 1932 and 1946 by J. A. Robbie et al.".