424 



MESOZOIC TIME. 



thence north, up the west coast. It is probable that all of England, 

 east of the Triassic, was submerged. The rest of it was divided into 

 three or more parts, — a southwestern (the peninsula of Cornwall and 

 Devon), a western (Wales), and a northern, — indicating the exist- 

 ence of an archipelago of British Isles in the Triassic period. The 

 rocks show that the waters between the islands were shallow and 

 partly brackish. 



In Europe, the Trias is found largely developed in regions east and 

 west of the Rhine, from northern Switzerland northward ; on the 

 east side, through Wurtemberg, Odenwald, Thuringerwald, and by 

 Giessen ; and on the west side, along the Vosges, by Strasbourg and 

 Metz, to Aix ; and, in each of these regions, they indicate brackish or 

 shallow waters, instead of deep seas. The beds occur also in other 

 parts of central Europe, in the eastern Alps, Poland, Russia, Spain, 

 etc., and in the far north, on Spitzbergen. 



I. Rocks: kinds and distribution. 



The subdivisions of the Trias are, — (1) the Variegated Sandstone ; 

 (2) the Shell Limestone ; (3) the Red Marls, or the Keuper ; (4) the 

 Rhaetic beds, between the Trias and Lias. The rocks are mainly red 

 sandstones and marlytes, with an impure limestone as the middle 

 member, in Germany. There is a " bone-bed " near the top of the 

 series, both in England and Germany. 



The subdivisions recognized in France and Germany are three in number; whence 

 the name, from the Latin tria, three. The beds are denominated, in these countries 

 and England, beginning with the lowest: — 



I. England. 



Salif erous beds, or New 

 Red Sandstone, 1,200 

 to 2,500 feet. 



II. France. 



1. Gres bigarre\ 



2. Calcaire coquillier. 



3. Marnes iris^es. 



III. Germany. 



1. Bunter Sandstein, 1,200 to 1,600 ft. 



2. Muschelkalk, 1,000 to 1,200 feet. 



3. Keuper. 



In English works, the names of the European beds, translated, are, — 1. Variegated 

 sandstone; 2. Shell limestone; 3. Red marlytes, or Keuper; yet they are often written 

 without translation. The names indicate the kinds of rocks. In England, they are 

 sandstone and mottled clays (marlytes), mostly red. In Europe, near the Rhine, a thick 

 fossiliferous impure limestone lies between a sandstone below and marlytes above. 

 The formation is sometimes called the Poecilitic (or, badly, Poikilitic), from the Greek 

 for variegated. 



This formation contains the principal salt-beds of Europe; and hence it is often 

 called the Salif erous system. The salt in Germany is connected with the middle group, 

 as in Wurtemberg, Avhere there are noted salt works. In Vic and Dieuze. Fiance, they 

 are in the upper; and a thickness of 180 feet of rock-salt occurs in the course of 650 

 feet of rock. The salt layers alternate with clay and gypsum or anhydrite. In Eng- 

 land, the upper part affords the salt; and at Northwich, in Cheshire, two beds of salt, 

 nearly pure, are 90 to 100 feet thick. 



St. Cassian series. — The beds of the St. Cassian series include, beginning below, — 



