19G ART. 2. — B. KOTÔ: 



to be seen only on the east coast where it occurs in association 

 with the Tertiary akeady mentioned. The basalt had already 

 begun its effusion during the Tertiary; but the period 

 of main outpouring seems to have been tlie Diluvial 

 period. This is also in accord witli the view held by Anert 

 and Cholnocky. 



The only large extent of the occurrence of common basalt" 

 in the south is the island of Quelpart, which is also the only 

 active volcano in south Korea. 



THE YOUNGER EFFUSIVES 



a) Basalt. — The iron-black basalt occurs at a few points 

 in association with the Tertiary of Yöng-il -^ on the east coast. It 

 is the Stielbasalt — a typical dolerite of coarse texture. Micro- 

 scopically it has a gabbro-like, typically ophitic texture with violet 

 titan-augite plate enclosing lath- shaped plagioclase and idiomorphic 

 olivine. Such a typically ophitic texture is rare in my experience. 



ß) The basalt'"'' of Quelpart Island is somewhat different 

 and belongs to the type of Mt. Fuji. It is either slaggy or com- 

 pact, and all of a bluish-gray colour. It is rich in plagioclase 

 and olivine with no augite phenocrysts in the blackish ground- 

 mass of the globulitic base which is admixed with grains of 

 common augite. It is tiie flow-basalt which is also widely 

 distributed in North Korea, forming volcanic mesas. 



1) The rocks of Quelpart were formerly consiclerecl to be all of the basalt family ; in later 

 ■works granite was created to make foundation. Mr. Inouyé (loc. c'd.) altered to pyroxene- 

 andcsite. From the band specimens at my disposal I cannot but reinstate the main rocks of 

 the island either as being basalt of the Fuji type or a variety of olivine-andesite, although the 

 occurrence of other rocks in small patches is not thereby absolutely denied (see page 141). 



2) See ante, jiage 9G. The same rock occurs at Tai-chho {^'ï^), on the coast northenst of 

 Chyang-gi, and also at Ho-am (Öt^) on the coast northeast of Ul-san. 



3) See ante, page 141. 



