Recieivs — The Geological Survey. 41 



racter, and the absence of pal^ontological guides, render their 

 manifold divisions often much more difficult to trace out in the 

 field. Nor should their importance be undei'-estimated, considering 

 that they occupy more of the superficial extent of the counti'y than 

 any other group of beds, and in questions of water-supply and 

 drainage, in matters relating to agriculture, road-metal, and brick- 

 earth, they exercise as much, and in some cases more influence than 

 do the older rocks. 



Moreover, since the Geological Survey was commenced, the science 

 of geology has grown very largely, and the rocks have been studied 

 in much greater detail. Hence it is only to be expected that the 

 work done thirty or forty years ago should require revision, and this 

 chiefly in the form of addition. Fresh subdivisions of the strata 

 have from time to time been made ; some owing to the labours of 

 the Geological Survey, others to the work of private individuals. 

 As an instance of the former, the subdivisions of the Wealden Strata 

 and Lower Greensand may be mentioned ; and of the latter, the 

 labours of Hicks on the older rocks of South Wales, of Hebert and 

 Barrels on the Chalk, of Moore on the Rhgetic Beds, of Allport, 

 Bonney, and J. A. Phillips, on Eruptive Rocks. These labours serve 

 to indicate the kind of new work that may necessitate revision of the 

 older surveys. 



In minute investigations, more especially in the collection of fossils 

 from certain quarries or zones, the local or resident geologist must 

 alwaj'S possess great advantages over those whose attention is mainly 

 given to tracing the rock-masses or groups of strata through large 

 tracts of country. 



With the accessions constantly made to our knowledge of each 

 formation, the labours of the Geological Survey must ever be on the 

 increase so long as the field-work lasts. And in addition to the 

 j^reparation of maps and sections, each officer has the task of writing 

 memoirs on the country surveyed, containing not only the informa- 

 tion he has himself gathered in the field and obtained from well- 

 sinkers, miners, and others, but all the facts which have been 

 published on the geology of the district. Those acquainted with the 

 literature of geology, of which the yearly " Geological Record " is 

 an almost bewildering illustration, know that the task is no light 

 one, and of course every year it becomes considerably greater. 



Nor must it be forgotten that much of the field-work now-a-days 

 is done on the maps of the scale of six inches to a mile, requiring 

 far more minute observation than the one-inch surveys. Some of the 

 maps not published on the larger scale are deposited in the Geological 

 Survey Office for reference. 



The importance of concentrating all the geological information is 

 perhaps best exhibited in the publications referring to Coal-fields. 

 There the evidence furnished by numerous mining operations is 

 tabulated in section, to show the direction in which the various seams 

 on the one hand increase in value and importance, or on the other 

 hand deteriorate or thin away. 



In the days of De la Beche, as '■' Observer " remarks, " the 



