THE DEVONIAN PERIOD 



573 



taries. The igneous rock occurs in many separate beds, showing 

 that there were many periods of igneous activity separated by 

 intervals of quiet. In much of central-western Europe the Devo- 

 nian 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, and from them large quantities of iron, tin, copper, and 

 other metals have been obtained. 1 



Fig. 413. Sketch map of Europe during the Devonian. The horizontal 

 lines represent the Lower Devonian; the vertical lines mark the addi- 

 tional areas where the Middle Devonian occurs. (After DeLapparent.) 



Russia. The Devonian of Russia is made up of beds of arena- 

 ceous 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 unconformable on subjacent formations. 



1 Geikie, Text-book of Geology, 4th ed., Vol. II, p. 999, 



