THE GEOLOGY OF SWITZERLAND. 
35 
desolate, and often almost without vegetation, but 
very beautiful from their richness of colour, and rugged 
forms. 
The Muschelkalk is often, as, for instance, on the 
Virgloria pass, a hard black limestone, splitting into 
thin slabs, which take a good polish and are used 
for tables. 
The earliest Mammals appeared in this period. 
To the Upper Trias belongs a thick deposit of 
grey, whitish, or yellow Dolomite, sometimes com- 
pressed into a grey or blackish Marble, which is 
known as Hauptdolomite, and, especially to the east 
of the Rhine, from its great durability often forms 
the highest and wildest ridges of the mountains. It 
is unfossiliferous. 
The account here given of the geography of 
Switzerland in past times differs, as will be seen, 
considerably from that indicated in the maps to 
Heeds Pvitncevcil World of Switzerland . Prof. Heer 
regarded the present boundaries of the different 
formations as indicating their original extension. This 
however is certainly not the case. The Jurassic strata, 
for instance, were not deposited near any land. There 
are no shore animals nor pebbles, as there must have 
been if they were coast deposits. 
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