Notes and Comments. 123 



■mostly untouchable. Under such conditions the study of 

 marine biology will soon be hopeless. That is the student's 

 point of view, but it does not require much imagination to 

 think of the point of view of the important fishes who would 

 find their food among such material in the sea, and of the sea- 

 birds. The war put into every fishing-boat on the coast a 

 motor-engine of one type or another, and the beautiful brown 

 sails which were the joy of the artist on the coast have all but 

 •disappeared. But the fishing boats themselves in dispersing 

 oil so abundantly, are smothering to death the small life on 

 which the fish feed. It is regrettable — but not surprising,, 

 remembering what Government Departments are — to know 

 that the Fisheries Department of the Board of Agriculture 

 consider the killing of the goose not to have gone far enough 

 yet to warrant their taking steps in the matter.' 



KNOW YOUR FAULTS. 



At the recent Annual Meeting of the Geological Society cf 

 London, the President, Mr. R. D. Oldham, F.R.S., gave an 

 ^address with the above title. It was devoted to a consideration 

 of the dangers of a loose use of words, especially to those of 

 the common fallacy of homonymy. The first instance taken 

 was that of the common classification of faults as normal and 

 reversed. The nomenclature originated in a region where 

 faults which hade to the downthrow are normal in the ordinary 

 •sense of the word ; this was extended to other regions, and it 

 became generally accepted that normal faults, in the technical 

 •sense, were normal in the dictionary sense, and, as a result of 

 "this double meaning of the word, the notion still lives on, 

 though experience has shown that it is certainly not in accord 

 with, and is very possibly the reverse of, the truth when 

 •extended from a special district to the world at large. 



REVERSED FAULTS. 



Reversed faults were then considered, and it was pointed 

 out that, although they involve a reduction in the horizontal 

 'dimensions of the faulted region, they could only in special 

 ■cases have been produced by simple horizontal compression. 

 A consideration of possible modes of formation led up to the 

 ■conclusion that the words upthrow or downthrow must be 

 regarded as indicating no more than the relative displacement 

 of the two sides of the fault, it being likely that simultaneous 

 movement of the two sides took place in opposite directions, 

 or in the same direction to different amounts. 



OVERTHRUSTS. 



Passing on to the special form of reversed fault known as 

 •an overthrust, the President pointed out that the word implied 

 the two concepts, that the upper block was thrust over the 



3921 April 1 



