ASYMMETRY OF THE NORTHERN HEMISPHERE 97 



mountain chains whose most southern visible point is represented by 

 the isolated outcrops of ancient rocks between the Caspian and the Aral, 

 in 46° 30', on the river Tschegan. 



The Ural mountain chains are followed in western Siberia by a broad 

 zone of folds which strike northeast. One of th ese chains causes the bend 

 of the Ischim. They extend across the Kirgis steppe toward Bajan Aul 

 and Karkaralinsk, disappear beneath the plains, and appear again by 

 Kolywan. Thence they extend farther northeast, cross the Ob and the 

 Tom obliquely, and abut against the Salair chain and coal basin of Kus- 

 netzk, and reach the Alatau of Kusnetzk. We name them the Kirgis folds. 



The mutual relations of the Ural and the Kirgis folds are not clearly 

 recognizable. One sees, however, that the two combined form the most 

 important part of the boundary of the west Siberian plain — that is, the 

 region of the Ob. In the extreme north of Siberia the traces of a little 

 known chain extend right across the Taimyr and reach the Arctic in 

 cape Tscheljuskin. This is the Tamyr chain (Bogen). 



A still larger chain begins with east- west strike at the mouth of the 

 Olenek. It goes straight through the delta of the Lena, turns southeast, 

 under the name Chara Ulach forms the Werchojan mountains, and finds 

 its continuation in the range north of the Ochota, generally called North 

 Stanowoj on our maps. 



The chain completes a new bend, which is like that between the Lena 

 delta and Chara Ulach. Its principal branch reaches in this way the 

 watershed of the Anadyr, the cape of the Tschuktschis, and the Saint 

 Lawrence island. This is the Werchojan chain. 



No connection with the American side is known.* 



The breaking up of the ranges (die Zertrummerung des Geberges) in 

 Bering sea and the covering of western Alaska by Tertiary sediments 



* Professor Suess tells me that "a paper since published by Raron E. Toll, of Dorpat, perhaps 

 brings the clue to the difficult question of the relation of the Alaskan Sierra to the Siberian moun- 

 tains." In this paper (Otsherk Geologij Novo-Siberikij Ostrowonj. Mem. Acad. Saint Petersburg, 

 1899, viii ser., vol. ix, no. 1) Baron Toll gives a geological sketch map of the western part of the 

 Merchojana curved chain, and pronounces his conviction that "the structure of this mountain 

 chain is concave — that is, that the rocks are folded against the interior of the curve." 



Professor Suess is of opinion that "in this case these mountains might indeed be regarded as 

 the true continuation of the Alaskan Sierra, both being equally folded toward the north, and the 

 same chain would then appear continued across Bering sea along the right side of the lower Lena 

 to the mouth of the Olenek, gradually diminishing toward this point." 



My own observations would agree better with the earlier conclusion of Professor Suess in the 

 body of the paper. 



Touching at Plover bay and coasting along to Indian point, on the mainland of Siberia, opposite 

 Saint Lawrence island, I saw only mountains of granitoid rocks of light and dark color, and found 

 boulders of the same and of crystalline limestone on Saint Lawrence island. 



At Port Clarence, on the Alaskan mainland opposite to the northeast and almost in Bering strait, 

 I found only the cleaved fossiliferous slates of the Yakutat formation, probably of Triassic age, 

 while the gneissoid axis of the Alaskan Sierra seems to trend southwest from the Tanana hills to 

 meet the sea far south of the delta of the Yukon. (B. K. E.) 



