512 Br. J. W. Evans — Presidential Address. 



(in black or white or colour), following the ordinarily accepted 

 •conventions. This course has been pursued by Professor Watts in 

 the geological map prepared by him to illustrate his Geography of 

 Shropshire. This increases the practical value of the map for many 

 purposes, but is only possible when it is not overburdened with 

 topographical detail. 



Some explanation, apart from the maps themselves, is, however, 

 needed if they are to be rendered, as they should be, intelligible to 

 the general public. The official memoirs which deal with the same 

 areas as the maps do not afford a solution of the difficulty. Excellent 

 as they are from the technical standpoint and full of valuable 

 information, they convey little to the man who h?s not already 

 a considerable acquaintance with the subject. What is needed is 

 a short explanatory pamphlet for each map, presuming no previous 

 geological knowledge, describing briefly and in simple popular 

 language the meaning of the boundary-lines and symbols employed, 

 and the nature and composition of the different sedimentary or 

 igneous rocks disclosed at the surface or known to exist below it in 

 the area comprised in the map. A brief account of the fossils and 

 minerals visible without the aid of a microscope should also be 

 included. The probable mode of formation of the rocks and their 

 relation to one another and the subsequent changes they have under- 

 gone should be discussed, and at the same time their influence on 

 the agricultural value of the land and its suitability for building 

 sites, as well as on the distribution and level of underground water, 

 should be pointed out. Some account too should be given of the 

 economic mineral products and their applications. 



These pamphlets should be illustrated by simple geological 

 sections, views of local quarries and cliffs showing the relative 

 positions of the different rocks, figures of the commoner fossils at 

 each horizon, and, where they would be useful, drawings of the 

 forms assumed by the minerals. Each pamphlet would be complete 

 in itself. This would involve a considerable amount of repetition, 

 but it must be remembered that different pamphlets would have as 

 a rule different readers. An alternative plan would be to follow the 

 example of the United States Geological Survey and reprint the same 

 brief resume of geological principles in every case with such 

 additions as are required to explain the meaning of individual maps. 

 There can, however, I think, be no doubt that an explanation 

 written expressly for each map can be made at once more easy 

 to understand and more interesting to those without special geo- 

 logical knowledge. 



That something further is required to render the information 

 contained in the Geological Survey maps generally available to the 

 public is illustrated by a correspondence that took place some 

 years ago in one of our leading provincial papers with reference to 

 the achievement of a manipulator of the hazel twig in discovering 

 water in the Triassic rocks of the south-west of Derbyshire. No 

 one seemed to realize that with the help of the Geological Survey 

 map published forty years before and the contoured Ordnance Survey 

 map more recently issued it was possible for anyone who possessed 



