49 



Miles and 

 Kilometres 



of the year is rough and choppy. Once inside 

 of Duke island and in Revillagigedo channel, 

 however, the sweep of the waves and winds is 

 broken, and quiet waters again prevail. 

 31 m. Cape Fox. — Cape Fox and the adjacent 



50 km mainland peninsula opposite Duke island con- 

 sist largely of massive and schistose greenstone 

 beds with occasional calcareous and argil- 

 laceous bands. These strata were formed 

 either at the end of the Carboniferous or in the 

 early Mesozoic. At present they are so highly 

 altered that their original character is rarely 

 apparent without detailed study. The same 

 belt, though slightly different in composition, 

 continues northward to Ketchikan and beyond. 

 62 m. Annette Island. — Annette island on the 



100 km. left is interesting, because of the development 

 of the forelands which fringe its shores, and 

 which have been considered by Gilbert to 

 indicate a secondary base level of erosion in the 

 physiographic development of this region. 

 Annette island has been set aside as a reserva- 

 tion for the Indians at Metlakatla under Rev. 

 Duncan. 

 78 m. Tongass Narrows. — Along the shore of 



125 km. Tongass narrows, greenstones with interbedded 

 argillaceous and calcareous rocks in various 

 stages of metamorphism are exposed. 

 80 m. Ketchikan. — -Ketchikan is the centre 



130 km. of the Ketchikan mining district in which 



copper and gold are the principal metals mined. 



Mining operations are confined chiefly to Prince 



of Wales island. 



93 m. Clarence Strait. — Entering Clarence strait 



150 km. the route continues northward to Zarembo 

 island. 161 miles (260 km.) whence it passes 

 across Sumner strait into Wrangel narrows. 



186 m. Wrangel Narrows. — At the entrance to the 



300 km. narrows the shores are composed largely of 

 greenstones, which, however, soon give way to 

 black slates and calcareous beds . 



208 m. Petersburg.— After passing Petersburg the 



335 km. course enters Frederick sound and approaches 

 the mainland, where the metamorphic influence 



34883—4 



