132 HISTORICAL GEOLOGY 



respects the " Old Red Sandstone " is much like the Chemung- 

 Catskill formation of America. 



The typical marine strata of Germany also contain many beds 

 of lava, thus indicating much igneous activity during the period. 



In west-central Europe much of the Devonian has been meta- 

 morphosed. 



Typical marine limestones, shales, and sandstones were exten- 

 sively deposited in Spain, France, Switzerland, much of Austria, 

 and Russia, but with Lower Devonian mostly absent from Russia. 

 Coralline limestones are prominent in the Alps. 



Other Continents. — The Devonian sea spread over most of 

 Siberia and into central Asia and China. Rocks of this age are 

 also known in various parts of southern Asia, northern and south- 

 ern Africa, Australia, New Zealand, and in South America they 

 appear to be more widespread than the rocks of any other Paleozoic 

 system. Most of South America must have been submerged under 

 a transgressing sea. 



Climate 



The general distribution and character of the fossils, as for 

 example the Corals of the Onondaga sea, indicate rather mild and 

 uniform climatic conditions. Possibly such red formations as the 

 Catskill and the "Old Red Sandstone" were formed under arid or 

 semi-arid conditions. What appears to be boulder clay with 

 striated pebbles, implies at least local glaciation in South Africa. 



Economic Products 



Oil and gas are principally derived from Devonian strata in the 

 great fields of western Pennsylvania, West Virginia, and western 

 New York. 



Flagstones of Devonian age are extensively quarried in south- 

 ern New York and in Pennsylvania. 



Black phosphate deposits occur in the Upper Devonian shales 

 of central Tennessee. 



Life or the Devonian 



Plants. — Of the Algce, both Sea-weeds and Diatoms are 

 known in fossil form, though they are not abundant. Certain 

 forms regarded as tree-like Sea-weeds were remarkable for their 



