218 GEOLOGY AS AN ECONOMIC SCIENCE 



Chalk are now pierced by hundreds of wells which 

 derive an almost unlimited supply of water from 

 the lower porous deposit. Similarly in other parts 

 of Britain we have such famous water-bearing strata 

 as the sand-rocks of the Jurassic System, extending 

 from the south to the north-east of England; and 

 the lower portion of the New Red Sandstone which 

 occupies the centre of England and passes north- 

 wards on either side of the Pennines. In other 

 countries, such as in the arid regions of Australia 

 and northern Africa, the application of geological 

 knowledge has led to the utilisation of underground 

 water-supplies which have done much to render 

 these districts habitable and productive. 



In any future scheme for the proper and uniform 

 control of our national water-resources, the geo- 

 logical structure of all our river-basins and catch- 

 ment-areas will have to be set out in great detail, 

 and the underground contours of our porous 

 water-bearing strata correctly given. As has been 

 said already, geological maps of such a scale as six 

 inches to one mile the scale adopted by the Geo- 

 logical Survey are the foundation of all questions 

 concerning water-supply, whether it be superficial 

 or underground. Superficial supplies are self- 

 evident, but the proper understanding of an under- 

 ground supply depends on calculations made by the 

 geologist from surface-observations, checked from 

 time to time by a careful record of borings or sinkings 

 that may be made to the water-bearing strata. 



