150 The American Geologist. September, 1904. 
"The peninsula is divisible on good grounds into two sections — north 
and south Korea — by a trench, in the geological sense, from the head 
of Gen-san harbour to Kang-hoa bay, at one corner of which is located 
Che-mul-pho, the emporium and entrance to the capital, Seoul. Thib 
trench or rift-valley is lava-drowned and is the only extensive volcanic 
field in south Korea, except the large basaltic island of Chyorjyu 
(Quelpart) off the southern coast of Chyol-la Do. This rift- valley 
or Grahen of Chyuk-ka-rong (510 m.) affords the easiest pa;ssage 
obliquely across the peninsula from the sea of Japan to the Yellow sea, 
and marks the boundary of various geographic elements:" (p. 52). 
"It is a rift valley or Graben obliquely crossing the geological strike. 
From the top of Nam-san in Seoul, we see on the east a regular cliff 
with its escarpment -toward us. It runs from the mouth of the Keum 
Gang to the head of Won-san harbour, and the well-fortified castle of 
Koang-jyu. 12 kilometers from the capital, stands on its edge. I call 
this the Koang-jyu ridge. The other ridge starts from the Ma-sing- 
nyong, the highest pass of 1020 meters (the second pass A-ho-by-nyong 
being 760 meters , between Won-san and Phyong-yang. and lowers at 
the mouth of he Imjin Gang. The Ma-sing-nyong ridge turns its fault- 
scarp to the east, making the counterpart of the Koang-jyu ridge, thus 
forming the trench-fault. Great basalt flow's occurred at the end of the 
Tertiar3\'' filling up the bottom^ and now forming the sterile plain cf 
Thyouuon or iron plain, so named from some resemblance of the lava 
to magnetite. The Chyuk-ka-ryong road goes gradually up tins lava- 
field, frequently crossing the canyon-like river-channel, and suddenly 
descends 'to Won-san at the above-named pass, which is the edge of the 
basalt-mesa and the boundary of two provinces."' (pp. 9-10.) 
"North Korea, as I have already stated, is divisible into two re- 
gions, viz., the plateau of Kai-ma on the north, and the hilly land of 
Paleo-Chyo-syon on the south. The boundary between the two is 
sharply marked. The north is a high plateau with a fault-scarp, facing 
southwards towards the depressed land, just as the Great Khingan 
(Hsing-an) turns to the east with its precipice towards Manchurin. 
The incurves of Korea bay on the west and that of Chyo-syon bay 
(Broughton bay) on the opposite side give some idea of the boundary 
as expressed in coastlines, and we can trace it in the interior as well.'' 
(PP- 3I-) 
"Five components of the Thai-Paik-san are the cliffs of tilted blocks 
sweeping along the coast of the sea of Japan, from which the right 
wing was successively thrown down to the sea bottom, as if it originated 
in disjunctive faults as an after-effect of the piling and pressing up of 
Hondo (Japan) toward the Pacific ocean." (pp. 56-57.) 
"The Han-san range resulted from a later geologic event than that 
which produced the Korean system. The former is composed of a 
number of tilted edges of faults which threw down block after block 
to the Southern sea. The sea-coast is dotted with an innumerable num- 
ber of. islets and rocks, and describes complicated in-and-out-curves. 
These peculiar features which characterize the coast, are nothing more 
