AGES OF MOUNTAIN SYSTEMS. 



Traces of this system exist in the gneiss and mica-schists of 

 Brest, the Cumbrian schists between Pontivy and Falaise, the 

 chloritic schists of Cherbourg, the Cumberland ranges, and at 

 Gotheburg and Upsal in Sweden, whence it is continued into the 

 southern part of Finland. It is also seen in the Pyrenees and in 

 Catalonia. 



207. III. SYSTEM OF LONGMYND. The green slate deposits 

 were forced up and inclined by this convulsion, and in the tranquil 

 period which ensued, the Bala 



lime-stone beds, d, fig. 120, 



were deposited by the ocean 



on their flanks, where these Bala 3 * Sea. 



strata are still seen in the 



same horizontal position. 



The date of the catastrophe 

 is therefore posterior to tVu c b ad 



lime-stone. 



In Brittany the green slate does not appear between the Bala 

 limestone d and the Cumbrian strata b, which shows that that 

 part of Europe was dry land while the Bala sea was making its 

 deposits. 



The stratification due to the Longmynd system has been traced 

 in Limousin in France, in the mountains of Morocco, in the Serra 

 da Estrella in Portugal, in the Erzgebirge in Saxony, in the gneiss 

 mountains of Moravia, and of those parts of Bohemia bordering on 

 Austria, on the north-east of the Wenner lake in Sweden, along 

 the coast of the Gulf of Bothnia in Finland, and along that of 

 Wiborg on the other side. 



208. IY. SYSTEM OF MOEBIHAX. The convulsion which produced 

 this system upheaved the Bala 



formation d, fig. 121, throw- 

 ing its strata, previously hori- 



zontal, into an inclined posi- n Sea - 



tion. In the tranquil period 



which ensued, the mountains 



thus formed were washed by deb a 



an ocean and seas in which were deposited the Silurian formation/, 



which is still horizontal, on the flanks of this system. 



This convulsion, therefore, immediately preceded the Silurian 

 period, and was posterior to the deposition of the Bala 

 limestone. 



The system of Morbihan is very extensive ; it is traced in the 

 mica-schists and gneiss of the Loire Inferieure, in the islands which 

 terminate the south-west coast of Brittany, in the granitic plateau 

 which extends along that coast beyond Parthenay, and over part 



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