Tectonic Geography of Asia. Hobbs. 151 
than the outcome of the joint-work of the orogenic movements that 
gave form to the Korean and the Han-san ranges. The inletj are the 
remains of tectonic valleys, while the headlands represent the ridges. 
Especially remarkable is the narrow canal of the free port, Masan-pho, 
which presents the outline of a compound cross with a single axis, 
due to the Korean and Han-san ridges which intersect each other on 
both sides of the entrance." (pp. 57 and 58.) 
"A great number of small ridges or fault-scarps traverse like a 
gridiron the whole of Paleo-Chyo-syon. The region is somewhat sim- 
ilar in its geological structure to the western half of Shan-tung. Well- 
established rules can be scarcely discovered in the arrangement of ridges. 
The whole tract is broken up into a number of long orographic blocks, 
each being of old sedimentaries, mainly of grey tabular limestone. Each 
block is tilted along the long side with steep walls, while it slants 
gradually towards the opposite direction. Some of the equatorial ridges 
may be brought into connection with the tectonic line of Shantung, e.g., 
Myor-ak-san of Hoang-hai Do, while others of the same group are dif- 
ficult to correlate with any known system. Meridional ridges, though 
coinciding in direction with some of the Korean system, do not har- 
monize with each other in position, nor in magnitude of disturbance; 
the general plan of the west coast, however, seems to have been great- 
ly influenced by them. 
In short, the intersecting fault-scarps of Paleo-Chyo-syon inserted 
between the Sinian and Liau-tung systems seem to be the result of a 
passive movement and after-efifect of the still greater tectonic disturb- 
ances which gave to the crust-block of the Korean peninsula its present 
form."' (pp. 58 and 59.) 
OUTER GLACIAL DRIFT IN THE DAKOTAS, 
MONTANA. IDAHO, AND WASHINGTON. 
By Warren Upham, St. Paul, Minn. 
The outermost boundary of the glacial drift across the entire 
northern part of the United States, from the Atlantic to the 
Pacific, was first fully mapped in a somewhat detailed man- 
ner by Chamberlin in 1888: though durmg the preceding twen- 
ty years the eastern half of this boundary had become known, 
with increasing accuracy and definiteness, from the work of 
many observers, mapping it between the Xew England islands 
and the Mississippi river. Comparing Newberry's map of 
the margin of the drift area,* as it was imperfectly known 
• Map showing Drift Area and BearinRs of Glacial Fnrro\\-s, Report of the 
Geological Survey of Ohio, vol. ii, 1874, at page 76 of the chapter on Surface 
Geology (pp. 1-SO. ) 
