CHINA, MONGOLIA, AND JAPAN. 99 



fracture. Fragments break off with a very hackly surface. The structure varies 

 from shghtly ceUular to scoriaccous, the cells being lined with a light greenish or 

 bluish film. It contains thin crystals of white, glassy felspar, the number of which 

 seems to be in an inverse ratio to that of the cells. The felspar is, at least in 

 part, a triclinic variety. 



The Tomari creek, which enters the sea near Shimakomaki, brings down among 

 its rubble, diorite, granular limestone containing nephrite, clay schist, and varieties 

 of quartz and jasper. This stream rises in the hiUs that have furnished, in part at 

 least, the auriferous gravels of Kunnui, and it is probable that similar deposits 

 occur also in the valley of the Tomari. 



August 29th. Embarking in a .large boat we sailed close under the lofty cliffs 

 of a grandly picturesque, but dangerous coast, as far as Setanai. 



The volcanic conglomerate exists as the principal formation of the coast, between 

 Shimakomaki and Setanai. At Cape Shiraita the thickness of the conglomerate, 

 above the sea, is between 100 and 200 feet; above this is a bed, perhaps 150 feet 

 thick, apparently of a looser material, with many white fragments scattered through 

 it ; and, finally, covering this, for a distance of one or two miles, is a bed of lava, 

 150 to 200 feet thick. 



From this point to Cape Moteta the cliffs are entirely of the volcanic conglomer- 

 ate, of which a lower bed is sometimes visible, with white fragments, those of the 

 upper beds being dark brown or black. 



At Cape Moteta the volcanic conglomerate, occupying the lower part of the cliffs 

 to the height of between 100 and 200 feet above the sea, is covered by a thick bed 

 of columnar lava. Near this point a broad dyke rises through the conglomerate 

 to the overlying lava bed, but it was impossible to determine, at a distance, the 

 relative ages of the latter and the dyke. 



Numerous dykes traverse the conglomerate between Cape Moteta and Setanai. 

 At Abura the latter approaches sandstone in texture ; at one place it was seen to 

 pass abruptly into a white deposit, probaby a pumiceous tufa. 



South of Abura the conglomerate is covered by a lava bed, and this by white, 

 apparently tufaceous, strata. 



Several miles north of Setanai a thick bed of columnar lava is visible, high up 

 the face of the cliff, lying between two members of the neptuno-volcanic formation, 

 and dipping gently toward the south. Before reaching Setanai a thick flow of lava, 

 beautifully columnar and probably the continuation of the bed just mentioned, 

 occupies the lower half or more of the cliff, while needles of the same rock rising 

 high out of the sea form picturesque islands. 



This rock is a dark brown, much weathered, cellular lava. The cells are coated 

 with a soft, brittle mineral, dark green in the fracture, and light bluish-green on 

 the surface ; and being flattened and parallel, with their planes at right angles to 

 the axes of the columns, they give to the rock a slaty structure. Overlying this 

 lava bed there are strata of tufa-conglomerate, made up mostly of fragments of 

 cellular and scoriaceous volcanic products. 



Just south of Setanai the Toshibetz — here several hundred feet broad — the river, 

 on which lie the gold washings of Kunnui, empties into the sea — its valley, here 



