150 INDEX TO THE STRATIGRAPHY OF NORTH AMERICA. 



The preceding summary represents Logan's conclusions in assembling the 

 results of his observations. The measured sections are given by him in detail and 

 may be abstracted as follows: 



Between 1 and 2 miles inland from the northeast side of the East Arm of Bonne Bay 

 [northern Newfoundland] there arises a range of hills of Laurentian gneiss, 2,000 or 3,000 feet 

 in height, on the flank of which is exposed the following measured section: 



A. 



Feet. 



1. Blackish-blue fine-grained slate. Of this slate only 105 feet of the upper part are seen; the 



lower part is concealed in the space between the upper portion and the gneiss and may 

 comprise a thickness of about 230 feet 335 



2. Blackish-blue slate interstratified with gray quartzites, in beds of from 6 inches to 3 and 4 



feet. In the 80 feet at the bottom the quartzites greatly predominate, and they constitute 



15 feet at the top, while the intermediate 175 feet consist chiefly of slate 270 



605 

 B. 



1. Light-gray, yellow- weathering limestone, in beds of from 1 to 3 inches thick, interstratified 



with blackish-blue, slightly calcareous slate, both containing small specks of silver-white 

 mica, which are more abundant in the limestone than in the slate. The limestones hold in 

 abundance fragments of trilobites, chiefly belonging to three or four species. Among them 

 is Paradoxides (Olenellus) vermontana, a new species of Bathyurus, and the pygidium of a 

 species so closely resembling B. extans of the Birdseye and Black River formation that it 

 can scarcely be distinguished from it and may possibly be the same 80 



2. Grayish-green micaceo-arenaceous shale, interstratified with a few beds of grayish quartzite 



weathering slightly yellow 80 



3. Strata concealed 30 



4. Reddish granular quartzite in thick beds 105 



5. Gray and grayish-green micaceo-arenaceous shale in beds from a quarter of an inch to an 



inch thick, interstratified with a few beds of gray, very ferruginous sandy dolomite and 

 fewer of gray quartzite 127 



6. Reddish quartzite, in beds of from 1 to 2 feet thick 34 



7. Gray arenaceous dolomite, weathering yellowish brown, interstratified with reddish quartz- 



ite, in beds 'of from 1 inch to 1 foot thick, and with reddish and grayish micaceo- 

 arenaceous shale, predominating toward the top. The beds of dolomite and shale contain 

 fossils, among which are Oholella chromaticaf , Obolus labradoricus, Paradoxides vermontana, 

 Conocephalites, a new species of Bathyurus, and one or more undetermined species of 

 Salterella 27 



483 



1. Whitish quartzite in beds of from 6 inches to 2 feet, interstratified with light-gray micaceo- 



arenaceous shale, in layers of from 6 inches to 1 foot, which occur at intervals of from 5 



to 10 feet 150 



2. White and reddish quartzite, in beds of from 1 to 3 feet thick, interstratified toward the 



bottom with a gray arenaceous dolomite, weathering yellowish brown 160 



3. White and reddish quartzite, in beds of from 1 to 3 feet thick, interstratified with greenish 



micaceo-arenaceous shale, constituting about one-half the amount 90 



4. Gray pure limestone, in beds of froml to 3 feet thick, marked with afew reticulating strings 



of yellowish- weathering dolomite. The rock is a mass of comminuted organic remains, 

 among which are Paradoxides vermontana and undetermined species of Bathyurus and 

 Salterella, as before 20 



5. Blackish-blue soft shale, interstratified with gray, yellow-weathering limestone, probably 



magnesian, in beds of 1 or 2 inches thick. The quantities of shale and limestone are 

 about equal, and the whole is intersected by reticulating strings of calc spar 35 



