CHINA, MONGOLIA, AND JAPAN. 9I 



The only formation seen was the terrace deposit, till near the divide, when an 

 obscure green wacke was found in place, and near this a greenish-black amygdaloid. 

 Large blocks of granite were also seen here, and this rock is probably in place 

 near by. 



Descending to the west we entered the valley of the Toshibetz, a large creek, 

 navigable with small, flat boats, and soon reached the gold washings of Kimnui. 



This part of the valley occupies a broad depression, perhaps 15 miles long by 7 

 broad, and raised several hundred feet above the sea. It has been filled with the 

 recent terrace deposit, and subsequently eroded in part, after which an extensive 

 deposit of auriferous gravels, etc., has taken place over at least a considerable part 

 of the area. 



In one of the side valleys the older rocks are exposed, and here the gold bear- 

 ing drift was found resting, in different places, on an argillite similar to that seen at 

 Washinoki, and containing the same vermiform fossils, in strata striking N. 85° W., 

 and dipping 50° northerly, and on an amygdaloid similar to that on the divide. 

 Not far from here the terrace deposit overhangs the creek in a high bluff. Out 

 of the base of this precipice I obtained a number of well-preserved fossil shells. In 

 the same bed were found Ostrese, Pecten, Scalaria, Terebratula, Nuculina] Serpula? 

 Corals, Bryozoa, and fragments of a thick shell with cross-fibrous structure. Some 

 of the shells retained, at least in part, their organic matter and nacreous lustre, 

 and one species of Pecten appeared to be identical with a species living in the 

 adjacent seas. 



At one end of this bluff is a large rock of the amygdaloid in place, which has 

 been exposed by the erosion of the terrace deposit, and on it are incrustations of 

 SerpulEB. 



This amygdaloid contains masses of a green rock resembling jasper, in which are 

 scattered flakes of native copper. Blocks of manganese (binoxide) in the immediate 

 neighborhood seem also to have come from the amygdaloid. 



The auriferous gravel occurs along both sides of the river in the form of a plain, 

 which descending gently from the hills faces the stream with a bluff. The whole 

 district appears to have been worked in former times, though when appears to be 

 unknown. Broad and deep canals of considerable length were dug to bring water 

 from up the creek, and a well arranged system of "ditch diggings" seems to have 

 been carried on. All these workings are covered with a dense growth of trees, 

 apparently not differing from the surrounding forest; some seen in the ditches being 

 as much as eighteen inches in diameter. The method of washing the gold does not 

 seem to have differed from that now used by the Japanese. 



The principal rocks, that have contributed to form the auriferous drift, are varie- 

 ties of granite, chloritic and micaceous schists, quartzites, and amygdaloid, with 

 geodes of chalcedony from the last mentioned rock. Rolled fragments of binoxide 

 of manganese are frequent also, perhaps derived from the amygdaloid. The con- 

 centrated sand of the washing is principally magnetic iron associated with zircon 

 sand. 



The manner of working the deposit is ingenious, and wiU be understood by 

 referring to the annexed diagrams. 



