In these days of satellite navigation devices, I hope that I am not alone in my need to carry both topographic and geological maps on travels in the UK. Research trips can involve a bundle of each type. For a ‘holiday’ the bare minimum is a detailed road atlas and the ‘ten-mile’ geological map. This 1:625 000 scale yields two UK sheets detailed enough to be useful on car and train journeys yet compact enough not to be a burden. My copies of the third edition (1979) are falling apart at the seams due to my reluctance to buy the fourth edition (2001), which was topographically clearer but geologically similar. In the nick of time, a completely redrawn fifth edition has appeared, accompanied by explanatory booklets.
The new edition has been compiled directly from the BGS 1:50 000 digital database. The general map pattern is reassuring familiar, but the user notices a number of significant changes. The number of map units has been increased, allowing more detail to be shown in some previously uninformative areas. The map units now mostly comprise formalized lithostratigraphy – supergroups, groups or formations. The purely numerical scheme for identifying units has been replaced by a more informative period code and intraperiod number, such as K1 to K6 for the Cretaceous. There are many more faults represented, in a line width chosen to be clear but not obtrusive. The two sheets now have a significant overlap, helpfully including the North Yorks Moors, the Lake District and the Isle of Man. Most radically perhaps, there are cross sections, each at 2x vertical exaggeration and down to 15 km depth.
The new maps are a big improvement on previous editions, and should be a pleasure to use. The slightly increased folded size is a small cost to pay for the increased coverage and content. The inclusion of more faults explains many previously puzzling deflections in lithological contacts. This feature, and the increased lithostratigraphical detail, makes the maps more useful for teaching in particular. The rationalization by BGS of broad-scale UK stratigraphy is a routine but important contribution to describing UK geology. The cross sections offer stimulating interpretations of relationships at depth; congratulations are due to Graham Leslie for compiling these hostages to fortune.
The two new map sheets represent excellent value at £10 each. They are even better value if bought along with their explanatory booklets at £15 for the pack. These explanations, ably written by Audrey Jackson and Phil Stone, describe most of the named map units and weave them into a brief but reliable geological history of the UK. The text is aimed at the inquisitive non-geologist, but provides a good quick reference for the student or geology professional. The production quality is of the same high standard and style established for recent British Regional Geology guides; colourful but clear.
The fifth edition ten-mile maps are published exactly sixty years after the first edition of the format, now an icon of UK geology. Geologists, libraries and university teaching departments in the UK will want to upgrade from previous editions. Those outside the country can confidently buy both maps and explanations as a modern, accurate and attractive depiction of UK geology.
