290 The American Geologist. November, 1904. 
from its earlier connection and placed it in a nearly perpendicular 
position. 
7. Development of the Japanese Arc. It is clear that the pro- 
jecting portions of Japan do not correspond to the recognized charac- 
ters of compressed mountain ranges of the Alpine type. South Japan 
shows in the front an arc concave toward that portion of the earth 
space lying in front ; we could compare it to a portion of the con- 
tinent taken from the Tsinling range and its adjoining ranges to the 
south. North Japan and Yezo on the other hand appear as fragments 
of an ancient continent of quite a different kind, placed transverse to 
the equatorial ranges of South Japan. If one considers the two parts 
of the continent of which the fragments are visible, not yet intersected 
by volcanoes but reproduced in full extent, scarceh' any portion of 
the coast could appear less adapted for the production of the mountain 
arc. But exactly as upon the continent and upon the coasts, the work- 
ing together of telluric forces furnished to the great fractures which 
they brought forth the tendency to join in great crescentic lines inde- 
pendent of the internal structure, and thus to develop an extended 
structure of the plateau block kind wi^h sickle-like border region and 
with upward-arching basin-like depression toward the interior. The 
Japanese inland country corresponds to these conditions in its entirety, 
the sea of Japan corresponds with the bottom of the basin. 
Like the other arcs which have been considered in these "studies," 
the Japanese hais a meridional and an equatorial arm. The meridional 
arm is a diagonal horst ; that is to say, its long sides (the eastern- and 
the western, or the outer and the inner) intersect in an acute angle 
the internal structure. The latter is as we have seen directed N by W. 
The axis of North Japan, and in like manner its coast line, curves 
from NE, through NNE, to N; hence correspondence with the strike 
never obtains. It follows that the force which here produced the 
meridional component of the arc on the west side of the Pacific 
ocean, as we have learned in all other cases, was_so powerful that the 
fault lines with it occasioned have courses without regard to any 
structures which were already present in its basement. Another 
prop'frty consists in its tendency in those places where the meridional 
arms join with the equatorial to form arcs, to continue again some- 
what further west and form meridional arms of new arcs in flanking 
position. It should be here recalled that the bathymetric lines of 
the great dcej) do not go around Japan, l)ut along the east side of the 
Bonin ridge in an arc which is convex t(i the eastward. 
In the equatorial arm of the Japanese arc, the conjecture already 
expressed is confirmed, that for the character of these components of 
the arcs, the Tsinling range constitutes a partition in so far as the type 
of the gridiron of blocks (Stattelroste) arising from tensional frac- 
tures, as it occurs in Daurien and North Chamiel, does not appear to 
occur on the south side of that range. Of the Japanese equatorial 
limb every trace in fact is lacking. Otherwise, the lines of the 
Sinian system are dominant in the general plan. However, the 
deformations which IIkv have suffered have influenced their courses. 
