556 Dr. J. W. Evans — Presidential Address. 



a series of typical collections illustrating the fauna and flora of the 

 more distinctive horizons in different areas. This is all the more 

 important, as the mode of preservation may be very different in 

 different places. It is probable that the geological surveys of 

 British Dominions and Dependencies and of foreign countries would 

 in many cases be able to supply such collections of rocks, mineral 

 deposits, and fossils as I have suggested. Where this is not possible, 

 the only practicable means of obtaining really typical collections is 

 to despatch a representative of the Museum, preferably one of its 

 own officers, to make one himself. The provision of such facilities 

 for the study of the geology of other lands is especially desirable in 

 London, in view of the number of students of mining and economic 

 geology who receive their training in this country and ultimately go 

 out into the world to find themselves face to face with problems in 

 which a true understanding of the local geology is absolutely essential. 



I shall not discuss here the important subjects of the indexing of 

 geological literature and the preparation of abstracts of current 

 publications. The former is already being efficiently dealt with by 

 the Geological Society, and the latter will, I trust, be provided for 

 in some way in the immediate future. 



I now proceed to indicate some lines along which it seems to me 

 probable that there are opportunities for progress in geological 

 research. 



In the investigation of the sedimentary rocks attention has been 

 usually directed mainly to the larger and more obvious features, and 

 these have sufficed to afford considerable insight into the conditions 

 which prevailed when they were laid down. The detailed study of 

 the minor structures or texture of these rocks by lens and micro- 

 scope has, on the other hand, been comparatively neglected, though 

 it is capable of affording us valuable information that could be 

 obtained in no other way. There are, however, I need hardly say, 

 important exceptions, the classical researches of Sorby extending 

 over more than half a century, the investigations of Hutchings on 

 the argillaceous rocks, and much useful work in recent years on the 

 mineral constituents and microzoa of the sedimentary rocks generally. 

 But, although individual sediments have been carefully studied, 

 few, if any, attempts have been made to carry out a detailed 

 examination of the successive beds of a stratigraphical succession 

 comparable to the systematic zoning by means of fossils which has 

 yielded such valuable results. 



Not only ought the texture and composition of the individual 

 laminae to be patiently studied to obtain information as to the exact 

 manner of their deposition, but attention should be more especially 

 directed to the character of the transition by which one layer gives 

 place to another, so as to determine, if possible, the cases where 

 there has been a gradual passage without a break, and those in which 

 there has been a pause in the deposition of greater or less duration, or 

 even a removal of material, although nothing in the nature of an 

 unconformity, however slight, can be detected. Even in apparently 

 uniform deposits, such as Chalk and clay, variations in texture and 

 composition may be brought out by special treatment and reveal 



