the road on the west side of the Poronai river has long- been abandoned, and now 

 loaded horses find pains next to death in passing the numerous and extensive 

 tundras on the way. It is very remarkable to find that water is still very little 

 utilized in the inland communication of the island. 



The Outer Zone, or the eastern side of the depression, shows extensive regions 

 of Palaeozoic rocks and Crystalline Schists, with less extensive Tertiaries and 

 Cretaceous, besides Eruptive Rocks. This zone is formed by the Northeastern 

 Mountain-land extending on the east of the Poronai river, and the Susuya Moun- 

 tains lying between Cape Shiretoko and Dubki. There we find a region with 

 the lakes, Tunnaicha, Chipesani, and so forth, which in the opinion of 

 Kawasaki, may represent a minor zone of depression, corresponding to the region 

 ending at Cape Patience, and carrying the lakes, Solenuiya and others, on the 

 peninsula. 



About the northern, that is to say, the Russian part of Sakhalin, our observa- 

 tions are restricted to the post-road from Alexandrofsk, across the low mountains 

 with wide valleys on the west side of the Tymi river, down to Derbenskoe, and 

 further southward to Grodekovo, lying almost on the line of the 50th. Parallel. 

 There we must follow the " Saklialinski Kalendari ", for the year 1898 and regard 

 the Western Range as assuming a plateau-like character on the extreme north, where 

 Glehn mentions a ridge of about 2000 ft. in height, projecting out towards the 

 northern extremity of the Sakhalin Island. He points to the occurrence of only four 

 exposures of rock (fossil-less sandstone) to the north of Oidktö ; in that region 

 there are usually found wide tundras along the coast. A remarkable contrast of 

 the river Tymi with the Poronai is that the valley of the former is more narrow 

 and is covered with woods and grasses, nowhere showing the nature of the tundras. 

 The east side of the Tymi has not yet been described, but it is no doubt a part of 

 the Northeastern Mountain-land. 



The Inner Zone, or the west side of the Median Depression, consists essentially 

 of the Cretaceous, Tertiary, and Volcanic rocks ; but the Older Eruptives there are 

 also of importance. 



II. General Geology. 



The tri-zonal structure of Sakhalin, which has just been mentioned, is at once 

 recognized, by looking at any one of the now-existing maps of the island, however 

 inaccurate they may be in degree. On the " The Guide for Immigrants to 

 Sakhalin," 1906, published in Japanese by our Civil Administration, a map with 

 well revised place-names was given. The great unedited map by the famous 



