CAMBRIAN AND LOWER ORDOVICIAN. 149 



partial exposure at the end of the distance shows a continuation of the same alternation of 

 shales, limestones, and sandstones. Red, purple, black, and olive-green shales succeed, asso- 

 ciated with gray sandstones; some beds fine grained and close in texture and others coarse, 

 with transparent quartz, silvery mica, white feldspar, and very minute bright green grains, 

 probably of glauconite. A few thin layers of black bituminous limestone are interstratified 

 among the shales. Several corrugations are visible in a low chff, in which these beds are exposed ; 

 but the measurement across the shales is about 350 yards, and the dip, which is southwestward, 

 varies in inclination from 26° to 90°. 



Between these beds and the base of the Gaspe limestones there is a distance of about 800 

 yards across the shales, but the strata are only obscurely seen at intervals at the beginning and 

 end of the measurement. The strike appears to be uniform, being N. 62° W.; but only the 

 extreme edges of the beds are anywhere seen, and the dip is sometimes to the one side and some- 

 times" to the other, at inclinations varying from 50° to 90°. The strata consist of black shales 

 and thin hmestones, which become somewhat arenaceous toward the south side; and the last 

 beds, seen immediately in contact with the overlying Gaspe hmestones, are of jet-black shale, 

 yielding a black powder. 



M 21. NCJBTHERN NEWFOUNDLAND. 



* 



Logan ^**^ described the lower Paleozoic strata of northern Newfoundland 

 under the headings "Potsdam group" and "Quebec group." He first recognized 

 sixteen divisions and later reclassified them under letters. He says: 



In the ascending section of the Labrador and Newfoundland rocks the divisions were 

 arranged under the numerals 1 to 16. Some of these divisions have since been remeasured in 

 greater detail than before; while with respect to others, the examination of their equivalents 

 in other locahties has shown that these divisions include additional strata. In giving these 

 farther results, it wiU be convenient to designate the divisions by letters, and to indicate the 

 subordinate parts of each by numerals. To facihtate a comparison of the present results with 

 those stated in the previous chapter, a summary of the section already referred to is here given, 

 with the former numerals, but having the letters now to be used, prefixed. The thickness 

 formerly assigned to these divisions, and the locahties in which they were observed, are also 

 appended. 



Potsdam group [Cambrian]. 



Feet. 



A. 1. Red and gray sandstones Anse au Loup 231 



B. 2. Gray, reddish, and green limestones do 143 



C. 3. White sandstones, concealed Strait of Belleisle 250 



624 

 Quebec group. 



D. 4. Gray and reddish magnesian limestones St. Barbe Bay 150 



E. 5. Dark-gray limestones do 400 



F. 6. Dark-gray geodiferous limestones Port au Choix 400 



G. 7. Dark-gray limestones do 130 



H. 8. Grayish-blue limestones do 340 



I. 9. Light yellowish-gray magnesian limestones do 150 



K. 10. Gray and whitish magnesian limestones Point Rich 130 



L. 11. Light bluish-gray limestones do 130 



M. 12. Light bluish-gray limestones Table Head 550 



N. 13. Black bituminous limestones do 200 



2,580 



O. 14. Gray calcareous sandstones and black shales Cow Head 700 



P. 15. Gray and white limestone conglomerates do 700 



1,400 

 Q. 16. Greenish sandstones and red shales Bonne Bay 2,000 



6,604 



