360 PALEOZOIC ROCKS OF THE HUDSON BAY REGION 



Thickness, 

 in feet 



Pterinea occidentalis. 



Gypricardinia sp. 



Hormotoma whiteavesi. 



Hormotoma sp. 



Of. Stroparollus sp. 



Orthoceras sp. 



Leperditia Msingeri var. 



Leper ditia Msingeri var. fadulina. 



Isochilina grandis var. latimarginata. 

 4. Limestone, gray, thin bedded; exposed about one mile 

 below the first limestone rapids encountered on de- 

 scending the river 4 



3. Dolomite, brown, structureless, vesicular, without fos- 

 sils ; exposed in the bluff at the foot of the upper, or 

 first, limestone rapids encountered on descending the 



river '. & 



2. Ledge of gray, dense, irregularly bedded, undulating 

 and domed limestone, in layers 2 to 5 feet thick, com- 

 posed largely of stromatoporoid masses from a few 

 inches to a few feet in diameter, alternating with 

 zones of fine-grained, thin-bedded limestone 2% to 

 3l^ feet thick ; exposed at the upper limestone rapids 20 



Streptelasma pygmceum var. occidentale. 



Favosites sp. 



Stropheodonta acanthoptera. 



Stropheodonta sp. 



Schuchertella sp. 



Orthis flahellites. 



Cf. Whitfleldella julia. 



Hormotoma whiteavesi. 



Encrinurus sp. 



Leperditia Msingeri var. 



IsocMlina sp. 

 1. Limestone and dolomite, brown, fine grained, imper- 

 fectly bedded, with few fossils, showing one or two 

 bands of stromatoporoid structure; exposed on the 

 west side of a small island one-half mile above the 

 upper, or first, limestone rapids encountered on de- 

 scending the river 8^ 



WINISK RIVER SECTION 



Limestones of Silurian age outcrop along the banks of the Winisk 

 River in several places between 15 and 40 miles above its month. An 

 important anticlinal fold extending in a direction a little north of west 

 crosses the Winisk River valley 4 or 5 miles above the mouth of its tribu- 

 tary, the Shammattawa. At this place the base of the Silurian is seen fo- 

 rest unconformably on quartzites of pre-Cambrian age, the Ordovician_ 



