1XX PKOCEEDINGS OP THE GEOLOGICAL SOCIETY. [May I9OO, 



drawn attention. I soon saw that such a task was too great, and 

 that it would be better for me to content myself with little more than 

 passing allusions, devoting more detailed attention to a stratigraphical 

 subject of which our knowledge has greatly increased within my time. 

 In a small part of this advance I have been privileged to have a 

 share, through the nature of the work that I have had to do. 



That subject is the underground course of various 

 formations, as proved by shafts and borings sunk 

 through overlying beds. On two occasions already I have 

 attempted to summarize our knowledge in this line, but only for 

 special districts, 1 and it may be of some interest to take a more 

 general view and in a somewhat different way. 



Many years ago our knowledge of what was to be found deep 

 underground was almost limited to mining districts, whether metalli- 

 ferous or coal-bearing, and even in such cases the recording of details 

 was too often neglected, the value of such details not being at that 

 time understood. The great advantage of possessing careful records 

 of the beds passed through in shafts or borings has now been recog- 

 nized for some time, especially in such cases as trials for proving the 

 underground extension of Coal Measures beneath not only Permian 

 and Triassic rocks, but also beneath still higher formations, as, 

 for instance, in part of the Bristol Coalfield. 



In this work it is important to record details of the rocks above 

 the Coal Measures, so as to have some grounds for estimating the 

 thickness of those rocks in neighbouring localities. Thus the 

 widening of the areas over which coal may be worked leads to 

 further knowledge of overlying formations. Moreover, we also gain 

 information as to the range of the various seams of coal and of the 

 changes which those seams undergo, and are enabled to correlate 

 sections at some distance. 



The Vertical Sections and various Memoirs of the Geological 

 Survey supply much information of this sort ; but the greatest col- 

 lection of such details is the fine set of six volumes published by 

 the North of England Institute of Mining and Mechanical Engineers, 

 embodying an account of over 2350 sections. 2 



I do not, however, mean to pursue the subject of the search for 



1 ' Underground in Suffolk & its Borders,' Eep. Brit, Assoc. 1895 (Ipswich), 

 pp. 666-675 ; and ' The Deep-seated Geology of the Bochester District/ Trans. 

 S.E. Union Sci. Soc. 1899, pp. 1-11. 



2 ' An Account of the Strata of Northumberland & Durham as proved by 

 Borings & Sinkings,' 1878-1897. 



