THE VOLCANO ASO AND ITS LARGE C ALDER A 



515 



lava predominates beneath the surface throughout this whole 

 region. 



RADIATING LAVA FLOWS 



Some miles to the south and east of Aso-san the surface covering of 

 volcanic ejectamenta which has filled up and blotted out the ancient 

 features of the landscape in this portion of Kiushiu ceases to be a solid 

 sheet, and the underlying older formations come to light. But beyond 





Fig. 9. — Looking down into the northernmost vent of the modern crater, showing 

 the bottom and the sharp ridge of mud on the right between this and the next vent. 

 The vapor comes chiefly from burning sulphur. Taken from the rim on the west side. 

 Photo by Malcolm Anderson. 



the line of contact, lava streams continue for great distances, partly 

 burying the old river channels that radiate away from the region 

 occupied by Aso-san, this region being the source of most of the 

 large rivers of the island. Aso has evidently been the center of the 

 volcanic activity of central Kiushiu and the source of supply of the 

 erupted material mantling the region. The longest of the lava arms 

 extends down the Gokase-gawa southeast of Aso, and was followed 



