FORMATIONS AND PHYSICAL HISTORY 491 



merged before the beginning of the Cretaceous. The great igneous 

 formations associated with the Trias of the northwest appear to 

 have been made during the Triassic period, rather than at its close. 



Foreign Triassic 



Europe. In Europe, the Trias is exposed in many widely sep- 

 arated areas, the largest being in northwestern Russia; but the 

 system is better known in the western part of the continent. In 

 England, it is unconformable on the Permian, but on the continent, 

 generally conformable. It has a marine and a non-marine phase. 

 The non-marine (or Triassic) phase prevails throughout the north- 

 ern part of the continent, while the marine (or Alpine) phase is 

 found farther south. The former resembles the Permian of Europe, 

 and the Permian and Triassic of the United States. 



In general, the Upper Trias is more widespread than the Lower, 

 especially in the southern part of the continent, and is marine over 

 a wider area. The principal subdivisions recognized in Britain 

 and Germany are the following: 



Britain Germany 



Rhaetic Keuper 



Upper Trias Muschelkalk 



Lower Trias Bunter 



In Germany, the middle member is largely marine, and the others 

 chiefly non-marine. In England the system is often known as the 

 New Red Sandstone, though formerly the Permian was also included 

 under this term. It differs from the Trias of Germany chiefly in 

 the absence of the marine member. Both salt and gypsum occur 

 in workable quantities in some parts of England. The Triassic 

 beds of most of Russia are similar to those of western Europe. In 

 southern Sweden, the system contains coal. 



The non-marine formations of red color, so characteristic of the 

 Triassic system both in North America and Europe, afford another 

 striking intercontinental analogy, and doubtless point to a common 

 cause, or to similar widespread conditions. 



The Alpine or marine phase of the Triassic has its best develop- 

 ment in the eastern and southern Alps, and is made up of thick beds 

 of limestone and dolomite, alternating with thinner beds of clastic 

 rock. The limestone and dolomite are much more resistant than 

 the associated shales, and, as a result, erosion has developed a dis- 

 tinctive topography (known as "the dolomites") at several points in 



