392 INDEX TO THE STRATIGRAPHY OF NORTH AMERICA. 



greenstone, probably belonging to the Cache Creek group, have been noted .®^ In 

 studying the Boundary Creek district, in British Columbia, adjoining the State of 

 Washington, Brock ^™ again distinguished the Cache Creek group among the 

 metamorphic rocks of the region. He says: 



On Observation Mountain near Grand Forks and on the rounded hill a little south of west 

 of this and some of the hillsides on Newby's ranch are crystalline mica and hornblende schist 

 with a few bands of crystalline limestone. These highly altered rocks resemble lithologicaUy 

 those of the Shuswap series (Archean) but may only be the argillites and limestones found 

 elsewhere, in a more metamorphosed form. 



The argillites, in places altered to schists and hornfels, limestone, usually crystalline, 

 often highly so, quartzite, the latter occurring only sparingly, together with serpentine, which 

 occurs in many portions of the districts associated with these, form a group which closely 

 resembles the Cache Creek series described by Dr. Dawson and assigned by him to the Carbonif- 

 erous. In the Boundary Creek sedimentary rocks no fossils have been found, but they are 

 probably of about the same age as similar rocks occurring to the north and west and may, 

 on this ground, be provisionally classed as Carboniferous. 



N-O 8-9. SOUTHEASTERN ALASKA. 



At Freshwater Bay, in the northeastern part of Chichagof Island, in latitude 

 58°, occur limestones about 1,500 feet thick, which carry a lower Carboniferous fauna 

 that is related to the Mississippian of the interior of the continent but is of a 

 different facies. Kindle ^"^^ correlates the formation with the lower Carboniferous 

 of the upper Yukon and of the Cape Lisburne section. 



An upper Carboniferous fauna characterizes a limestone 600 feet thick which 

 occurs about Pybus Bay, Admiralty Island, in latitude 58°. Kindle gives the 

 following section: 



The oldest Carboniferous fauna which has been found in southeastern Alaska was obtained 

 at Freshwater Bay, in the northeastern part of Chichagof Island. This fauna was submitted 

 to Dr. George H. Girty, who states, in a report furnished the writer, that, "while not unlike 

 the American Lower Carboniferous or Mississippian, it resembles and probably should be cor- 

 related with the Russian Lower Carboniferous or Productus giganteus zone or Mountain lime- 

 stone." Freshwater Bay is the only locality visited where the Lower Carboniferous fauna 

 has been found in southeastern Alaska. This locality is important also because-the stratigraphic 

 relation of the Lower Carboniferous to the older rocks may be observed. 



On the northeastern side of the bay, and opposite the Silurian and Devonian limestones 

 already described, the Carboniferous limestones form a low, narrow peninsula. * * * The 

 thickness of the several divisions of the limestones which are exposed along the north shore 

 of this peninsula is indicated approximately in the following section; which begins about one-half 

 mUe above (northwest of) North Passage Point : 



Feet. 



(«) Breccia of large gray limestone fragments 100 



(d) Hard gray limestone, much fracttired by numerous irregular joints and breaking into small 

 irregular fragments on weathering. Large productoids common. Dip 30° to 90° toward 



southwest; strike K. 40° W 90 



(c) Gray limestone with frequent bauds of black chert. Fossils scarce. Strike N. 10° to 20° W.; 



dip 80° to 90° NE 275 



(b) Dark-gray limestone with black chert bands. Fossils abundant near upper and lower limits. 



Average strike N. 30° E.; dip 70° to 80° NW 250 



(a) Limestone similar to 6. Corals common 275 



990 



