THE VOLCANO ASO AND ITS LARGE CALDERA 505 



course over the comparatively flat plain and tumble down to 

 their junction at the outlet with gradients of 4 to 8 per cent. 

 or more. The northern one makes the descent the more rapidly. 

 The southern one on leaving the upper level of the floor drops over a 

 picturesque waterfall. 



The northern basin appears to be larger and rounder than the 

 southern one and its floor is even more level. Small parts of it were 



Fig. 4. — A portion of the ring wall, looking southwest across the cultivated floor 

 of the southern basin. The wall in this portion is considerably worn. The town of 

 Takamori shows in the distance on the left. Photo by Malcolm Anderson. 



flooded or marshy during April, 1905. Several small isolated and 

 fairly steep hills rise out of the northern basin. They were not 

 observed closely but looked as if they were composed of the same 

 material as the wall. 



The surface deposits of the floor appear to be chiefly fine sandy 

 material and coarse yellow sand and gravel in horizontal layers, 

 covered with black, slightly sandy soil. The deposits were probably 



