CHAP. VIII.] TRIASSIC PERIOD. 127 



found their way into the southern sea were altered, and 

 their waters deflected into the depressed areas, forming large 

 inland seas or salt lakes. Professor Ramsay compares the 

 geographical conditions of northern Europe during Triassic 

 times to those of central Asia at the present time, where 

 from the Caspian Sea for 3,000 miles to the eastward and 

 far south toward the Himalayah there is a comparatively 

 rainless district in which all the lakes are salt, except those 

 which have an outlet to some lower lake. 



Confining our view now to the area of the British Islands, 

 we find in early Triassic times three separate areas of de- 

 position (see p. 116) : one in the south, where the Devon 

 and Dorset Trias was formed ; one in the north-west over 

 the site of the western Dyas lake ; and one in the north- 

 east, which was probably a long and narrow tract bounded 

 on each side by a range of mountains. 



Let us first consider the conditions which prevailed in 

 the southern area at this epoch. The deposits which form 

 the lower part of the Trias in this district are such as 

 might be accumulated in a lake that was bounded by high 

 and rocky land ; the succession of breccias, sandstones, and 

 marls is strongly suggestive of deposition in water, and 

 there can be little doubt that the lake-basin was bounded 

 on the west and south by land of a rocky and mountainous 

 character, which extended continuously from Devon and 

 Cornwall into the north of France. On the east and north 

 the lake was enclosed by a projecting mass of land which 

 stretched from France and Belgium through the south- 

 east of England, and was united to Wales by an extension 

 of the Mendip Hills ; but as the ground on the north was 

 subsequently covered by the Keuper marls, we may infer 

 that it was lower than that which lay to the west, south, 

 and east. 



The western coasts of the lake seem to have been espe- 

 cially steep and rocky, the mountains probably coming 



