where an extensive forest is found, owing to the underground 
water afforded by the lakes. 
Although the mountain is entirely in a dormant stage, there 
is still observed some heat, 50°C in the rocks on the top, — an 
indication that the volcano has but recently ceased to be active. 
The inclination of the flank near the top is rather steep, mea- 
suring 34°-32°, then gradually becoming a more and more 
gentle declivity of 25°-17°, and at last most gently sloping league 
after league almost to a level. The shoulders of this volcanic 
cone are in all respects quite symmetrical, and its general outline 
is comparable to a logarithmic curve, so uniformly do the flanks 
slope in all directions. 
The flanks are, as has been stated by Dr. T. Hirabayashi, 
all covered with lava broken into jaggy blocks, or invested 
with volcanic ashes. Generally speaking, the mountain is covered 
with lavas and cinders from the peak down to an elevation of 
1500m., but the basal portion below is covered with tufas, sand 
and pebbles. It must be admitted however that there is a little 
local difference on the different sides, — for example, on the N. 
W. side the Aogigahara-lava occupies a very extensive area 
reaching down to an elevation of 1000m., while on the cast the 
volcanic ashes and pebbles cover a broad area at the base and 
reach up as high as to elevation of 2500m. 
Lavas are necessarily accompanied by scori:e of various 
kinds. I may mention here that lava, when it consists of jaggy 
blocks, can absorb much water in its substance and is more 
likely to hold water upon its surface. When lava is thus broken 
into jaggy blocks, it is all the better for retaining water ; be- 
cause from a smooth plane surface water will run off rapidly ; 
but with a rough surface, it has more chances of being retained. 
Not only has rough ground more power to hold water for the 
plants, but also it supplies the young seedlings with shelter 
sufficient to help their growth. But, if the lava consists of 
scoria, the case is a little different. Scoria is hard and glassy, 
