///. Geology of the Japanese Empire. 



JPart I, 

 Geology of Japan. 



By 



Nobiiyasu Kanehaea, 



Director of the Imperial Geological Survey of Japan. 



Contents 



1. General Remarks 



2. Sedimentary Formations 



(a) Palaeozoic Group 



(b) Mesozoic Group 



(c) Cainozoic Group 



3. Igneous Eocks 



4. Volcanoes and Hot Springs 



5. Minerals and Mineral Deposits 



1. General Remarks. 



From a geological point of view, the islands of the Japanese 

 Empire are nothing but the summits of a great mountain system that 

 flanks the Pacific side of the Asiatic continent, from which they were 

 detached by the depression of the intervening seas. Consequently the 

 country is devoid of extensive plains, and in most parts its features 

 are mountainous. 



Along the whole length of the chain from Hokkaido to Taiwan 

 (Formosa), the geological structure of the islands reveals the existence 

 of two parallel zones curving towards the northwest. Of these, the 

 one that lies on the convex (Pacific) side is usually called the " Outer 

 Zone ", and that on the concave side, the '' Inner Zone ". In the 

 former, the geological formations, ranging from the Pre-Carboniferous 

 to the Cainozoic, are better developed and more regularly arranged, 

 while in the latter there prevails a much complicated structure and 

 various eruptive rocks make their appearance. 



