EDITORIAL 



297 



tripetal movement. The former are quiescent periods so far as 

 the relations of platforms and basins are concerned, the latter 

 are periods of readjustment. The dynamical conception 

 involved in this view is somewhat radically different from that 

 involved in the literal conception of quiescent periods as 

 periods of no crustal movement at all. 



In the accumulation of the general stresses which issue in 

 general readjustments, local stresses of special intensity must 

 almost necessarily be developed and these may reach such a 

 degree of intensity as to lead to local readjustments. These local 

 readjustments may result in the distribution of the stresses over 

 wider areas, and these wider areas may in time yield and trans- 

 mit the stresses to still broader fields until the stresses become 

 general and reach such a degree of intensity as to issue in a gen- 

 eral readjustment. Local readjustments in the form of local 

 warpings and faultings may be incidents of the general quiescent 

 stages, and like them may be essential antecedents of general 

 readjustments involving the formation of mountain systems and 

 similar pronounced phenomena. 



T. C. C. 



THE DUPLICATION OF GEOLOGIC FORMATION 



NAMES 



The custom of giving more or less local geographic names 

 to geologic subdivisions has become so universal that we are 

 even now duplicating the use of such names to a considerable 

 extent. Geological literature is of too great bulk for the work- 

 ing geologist to attempt to ascertain whether or not names 

 which he proposes to use have been preoccupied. To illustrate 

 what the present system is leading to a few instances of some 

 prominence will be cited. 



In 1883 Hague described, in a report of the United States 

 Geological Survey the Eureka quartzite, a subdivision of the 

 Silurian in the Eureka district, Nevada. In 1891 Simonds and 



