JIMBO : GEOLOGY OF JAPANESE SAKHALIN. 1 5 



mile. At a place 50 miles to the west of Mauka, Mr. XakamL'RA. one of the 

 assistants of Mr. K. W'aDA, found a line 190 fathoms long not reaching the bottom. 

 From Kushunnai to Raicliishka, a sounding of 20 fathoms is made beyond 5 miles off 

 the coast. At Ushoro. water is deeper, showing 50 fathoms at the same distance, a 

 gradual shallowing being however observed towards the north, as we proceed on 

 into the Mamiya strait (Strait of Tartar}^), which is only about 5 miles wide and 

 allows a free passage on sledges across the frozen sea in winter. 



Between blunt capes, mostly consisting of andesites and other eruptive rocks, 

 there are slight concavities of coast line wliich are only used in summer seasons, 

 when the sea is calm with easterly winds prevailing. From the later autumn to 

 the next spring, rough westerj* winds sweeping over the Asiatic coast, leave no 

 shelter to ships on that coast. From Cape Xotoro to Tokombo (about 90 km.) there 

 is no plain on the bottom of coast-hills, and there swift currents and numerous 

 series of reefs hinder the progress of the fisheries. From Tokombo to Cape 

 Chiikai about 120 km.) the generally terrace-shaped character of the coast land 

 is conspicuous. The onh' exception is the sandy plain with dunes, found at Notoro 

 (not to be confounded with Cape Xotoro on the south), wliich is said to be 

 slowl)- decreasing, on its whole length of about 20 km. On the terrace coast, there 

 are level grounds, from about 10 meters to more than 100 in width, extending along 

 the beach. There are again more or less level lands on the back, 6 to 50 meters 

 in height ; and equalh- flat shelves in front, co\ ered b}' water of 2 or 3 ft. in depth. 

 These submarine shelves of rock, which are found not only on this part of the sea- 

 coast but also at many other places of Sakhalin, where the Tertiär}' rocks are pre- 

 vailing on the coast, is particularly well developed on a stretch of about 72 km. from 

 Tokombo to Tokotan. Their width varies from about 30 to 300 meters. The 

 depth of water over them is 3 to 5 ft. at their margin, where it is deepest, and 

 beyond which we find a sounding of 3 to 5 fathoms. From Tokotan to Kushunnai, 

 shehes are found here and there ; on the north of Ushoro. they lie deeper in the 

 water, which is one fathom in depth close to the beach line. 



The terrace coast shows the continuation of valleys cutting the shelves in the 

 form of broad clefts, which admit at Mauka entrance to small steamers of about 200 

 to 300 tons. The most important roads for ships there are Tokombo. Oko, Ohoto- 

 mari, Mauka (the most important and now well populated town on the west coast), 

 Rakumaka, Xotasam. and others. 



From Chiikai to Kushunnai (about 55 km.) topography of the coast-line is 

 ver\- different from that of the above mentioned region. The hill coming more 

 close to the sea-coast, often shows precipices of about 30 meters in height. 



