Tcctuiiic Gcoi:^rapliy of Juistcm .Isia. — Ifobhs. 285 
chiiia-yania ( -5,^o in.), distant (/) kilimulc-rs ; from it a line nf the 
scries dii-fctod S -'5" IC lnuclies tiie peaks Yatsugadake (2932 ni.), 
Kayagadake ( i_'40 ni.), Fnji-yania (3728 m.), Aschitaka-yania 
(1187 in.), Aniagisan (1386 m.), and reaches l)eyond the island ot 
Niijinia to the island of Myakejinia, which is distant from Tates- 
china 255 Ivilometcrs. Here it meets a loxodromically straight line, 
likewise sharp, and directed from N 10° W, to S 10° E, which extends 
through young and generally very small volcanic islands characterized 
for the most part by present activity, in a length of 1,200 kilometers. 
Belonging to it arc: 0-schima (34° 44' N), Miyakejima (34° 5'N),and 
with for the most part greater intervals, seven small islands and reefs, 
to Ponafidin and Lot's Wife (29° 48' N), then Rosario (27° 16' N), 
and the volcanic islands stretching from 25" 25' to 24° 18'. At a distance 
of 130 kilometers to the east rises the almost parallel series but yet 
slightly curving into an arc (convex to the sea) of the somewhat 
larger Bonin islands, 120 kilometers long, for which series the Japa- 
nese use the name Ogasawara-jima. Yoshiwara has found nummu- 
litic limestone upon them. Based upon tha interlamination of tufa 
and upon other phenomena, the conclusion has been drawn that 
here the volcanic activity has reached from the Eocene time into the 
Aliocene, and since a subsequent elevation appears not to have occurred 
the entire series of islands must be considered as an older one in 
respect to that just mentioned. 
Soundings have shown that the islands are raised above the sub- 
marine ridge which has been designated the Bonin Ridge. It is not 
certain whi-tiier it can 1)e surrounded by the 2,oco meter line; yet it is 
probable that it extends southward to 2o''N. Concerning its relations 
to the ridge of the Mariannes, no conjecture can yet be made. 
The Great Japanese Folcano Arc (Bandai Arc). If the portions 
of the great continental framework which are alxjve the sea, marked 
out by the Japanese islands, allow the internal connection and the 
history of their ancient basement to be made out but incompletely, 
certain lines of great disturbance in later time, which were connected 
with important neo-volcanic processes, are so much the more distinctly 
drawn. Among these new dominating lines (Leitlinie)i) which came 
into being in middle Tertiary time, that one is by far the most striking 
which is genetically connected with the volcanic arc here under con- 
sideration. It follows neither the direction of the strike nor of 
recognizable ancient fractures, nor does it show any dependence upon 
the deflections which the north zone and south zone of South Japan 
have been subjected to on their east end, but it intersects each of 
these elements at arbitrary angles. The tendency of the .east Asiatic 
arcs which are convex toward the ocean, is, as was shown, not to be 
made out in any part of the fundamental complex; here in the great 
Bandai arc of volcanoes it holds true for the first time in a strict 
scflise. The arc intersects North Japan in the middle line and is like- 
wise marked out by massive volcanic formations as well as by Ijasins 
depressed upon either side. If westward from Satporo, in Yezo, we 
