THE DEVONIAN PERIOD. 447 



and Spitzbergen, and both divisions of the Old Red have been recog- 

 nized in Spitzbergen. 1 



West central Europe. — The Devonian of Germany is remarkable 

 for the proportion of igneous rock interbedded with the sedimentaries. 

 The igneous rock is principally diabase and diabase tuff, but other 

 varieties are also found. These rocks occur in many separate beds, 

 showing that there were many periods of igneous activity separated 

 by intervals of quiet. Igneous rocks occur in the Devonian in some 

 other parts of western Europe. 



In much of central-western Europe the Devonian strata have been 

 metamorphosed, and their structure is often complex. In not a few 

 places, especially where the sedimentary rocks have been invaded 

 by igneous rocks, mineral veins have been developed whence large 

 quantities of iron, tin, copper, and other metals have been obtained. 2 

 The Devonian of Germany also contains a little coal, showing that 

 the conditions for its formation were locally present. 



Russia. — The Devonian of Russia is made up of beds of arenaceous 

 and calcareous rocks, the former containing fossils related to those 

 of the Old Red sandstone, the latter containing fossils of a marine 

 fauna. The Lower Devonian appears to be wanting in much of Russia, 

 and the middle and upper parts of the system are generally uncon- 

 formable on subjacent formations. Except in the Ural region, where 

 Lower Devonian is present, the Devonian strata of Russia are not 

 notably disturbed. 



Comparison with America. — On the whole, the course of geological 

 history seems to have been less pacific in Europe than in America. 

 The great local unconformities within the Devonian system find no 

 parallel, so far as now known, in America, and the extreme develop- 

 ment of igneous rock in western Europe is not duplicated in America. 



In Europe as in America, there do not seem to have been notable 

 changes at the close of the Devonian. There seem to have been some 

 cnanges of level in Russia, Bohemia, and Great Britain, so that succeed- 

 ing strata rest with some measure of unconformity on the Devonian; 

 but over much of the continent the Carboniferous strata succeed the 

 Devonian conformably. In this again the European phenomena cor= 

 respond with those of America. 



*Geikie, Text-book of Geology, 4th ed., Vol II., pp. 1012 and 1013. 

 " Ibid., p. 995. 



