PHILOSOPHICAL SOCIETY OF WASHINGTON, 51 



Of the Transverse Valleys there are three classes : — 

 First : Diaclinal. 

 Second : Contraclinal, 

 Third t Conclinal. 



Grand Valleys are formed by the coalescing of distinct systems 

 of drainage, and their several parts may belong to two or more 

 of the different orders of valleys. 



The Valleys of the Colorado, Mississippi, and St. Lawrence 

 are examples. 



In considering this system of drainage in the Valley of the 

 Colorado, and the conditions under which it was formed, the fol- 

 lowing inferences are made : — 



First: That the elevation of the folds above the sea proceeded 

 but little faster than their denudation by rains and rivers. And 

 that it is not probable that the summits of the mountains were 

 ever much higher than at present. 



Second: That these folds w^ere not elevated simultaneously, 

 but progressively, against some fixed point of dry land. It is 

 probable that this fixed point of dry land for the east and west 

 folds was to the south, and that for the north and south folds 

 was to the east. 



Third : The axis of an emerging fold may fall on the land or 

 the sea side of the shore line, and thus determine the direction 

 of valleys. 



Fourth : The direction of valleys is sometimes determined by 

 the lithological character of the formations. 



A brief reference was made to the influences modifying the 

 contour of the valleys, to the general amount of erosion, and to the 

 distribution of the debris of such erosion, which is not carried 

 away to the sea. 



23d Meeting. March 23, 1812. 



The President in the Chair. 

 Mr. J. H. Saville presented a paper 



ON THE NEW JAPANESE COINAGE. 



