UMBO : GEOLOGY OF JAPANESE SAKHALIN. 3 



)et published, was revised at the same time : and this little study of fauna made 

 the real beginning of m}- researches on the geologj' of that island. I \ er\- much 

 regret that I have not yet found occasion to visit the ver>' rich fossil locality of 

 Mgatch, lying to the north of Alexandrofsk. which furnished him with the greater 

 part of his Tertiary Mollusks. 



With regard to the geolog>' of the island of Sakhalin in general, very- little has 

 been published, before the appearance of Kawasaki's work. In European 

 languages. SCHMIDTS descriptions of the Cretaceous fossils from Cape de la 

 Jonquiere near Alexandrofsk, the general report of travels by SCHMIDT and 

 Glehx. and BaTSEVITCHS •' Materials for the Study of the Amur region." in 

 Russian, may be mentioned as important. But the designation of rocks b\- 

 SCHMIDT and Glehx sometimes led SUESS to misunderstandings about the 

 geological structure of the island, in his •• Antlitz der Erde." in which he gives a 

 list of works connected with the island. 



I. Topographical Subdivision of the Island of Sakhalin. 



Sakhalin consists of two longitudinal mountain ranges, making the outer and 

 inner zones of sedimentär}- rocks, separated from each other b\- the Median line of 

 Depression, as was already recognized by KAWASAKI in his manuscript report for 

 the year 1905. There is only one dependent island of large size, called Kaibatö. 

 and the coast of the main island is almost free from islets and large rocks. The 

 Kaihyötö i Azarashijima, or Robben Island) is a little islet of great importance, 

 lying among the series of rocks extending from Cape Patience far to the south. It 

 is a breeding place for the sea mammals. The well-known Danger Reef (Kamen 

 Opasnoti) lying off Cape Xotoro (Cape Crillon, also called Kondözaki after the 

 war) is a little mass of eruptive rock, measuring about 7 meters in height, 7 in 

 width, and 30 in length. Flat reefs and submarine shelves are however of 

 common occurrence round the coast. 



The Median Depression is formed by the \alleys of the Susuya and Takoi 

 rivers on the south, and of the Poronai- and Tymi rivers on the north, and includes 

 broad plains, which on both sides of the Poronai river, assume the character of 

 tundras. This depression formed and still forms a part of the chief way leading from 

 Alexandrofsk o\-er low mountains down to the valley of Tymi. and further passing 

 over to the town of Korsakoff. On the south, the Russians succeeded in improving 

 the primitive Ainu track, which naturally proceeded on that beaten by bears. But 



* This river is also called - Plyi " in Glehns report, in Beiträge zur Kenntniss des 

 Ktissischen Belches. Ac. 1S68. I heard the name " Sungeshii " used by the Orokko. 



