150 W. II. Twenkofel — Silurian Section at Arisaig. 



the basis of the presence of Monograptus clintonensis, Retio- 

 lites 'geinitzianus venosus, and Anoplotkeca hemisj)herica. 

 Division II begins with dark carbonaceous paper shales, and 

 has in its upper half green shales with fine-grained sandstones. 

 It is believed to be coincident with Divisions B and B' of 

 Honeyman (1864 : 333), to include somewhat more than the 

 Upper and Lower Clinton or Division E2 of Fletcher (1886 : 

 37P), and to form the upper portion of the Arisaig formation 

 of Ami (1901 : 394). 



In this division there is an estimated thickness of over eight 

 hundred feet, which is probably less than the true thickness, as 

 some of the strata have been lost by faulting. 



2. From Arisaig Pier to the Lobster Factory there are no 

 outcrops. At the middle of Beach Hill Cove are exposed 

 about one hundred feet of black carbonaceous paper shales 

 that partly or wholly lie below zone 3. Strike almost E.-W., 

 but varying ten to twelve degrees either side. Fossils are 

 scarce, due to the much weathered condition of the shales. 

 Base of Honeyman's Division B and Lower Clinton of Fletcher's 

 section. 



3. Broken down cliff of dark to black rusty weathering 

 papery shales. Beds much disturbed, and in part the strike is 

 almost that of the shore. 



Estimated thickness .'_. 100 feet. 



Fossils abundant : Anoplotkeca hemispkerica, Anabaia anti- 

 costiana, Lingida cf. oblong a, Aeaste downingiw. 



4. Dark-gray to green and black fine-grained soft shales, 

 weathering rusty. Much disturbed. Strike K 50°-T0° W. ; 

 dip 30°-50° W., with many variations. 



Estimated thickness 215 feet. 



Fossils fairly abundant : Monograptus clintonensis, Anoplo- 

 tkeca kemispherica, Anabaia anticostiana, Gornulites flexuo- 

 sus, Calymena cf. tuber cidata. 



5. Dark-gray somewhat papery shales with a few hard bands ; 

 all weather rusty. Strike variable. N. 60°-70° W. ; dip 

 30°-10° W. 



Estimated thickness . 50 feet. 



Monograptus clintonensis, M. priodon ckapmanensis, Retio- 

 lites geinitzianus venosus, Orbiculoidea tenuilamellata, Dal- 

 manella elegantula, Schuchertella sp., Chonetes tenuistriata, 

 Anoplotkeca kem.ispkerica, Anabaia anticostiana, A. depressa, 

 Gornulites flexuosus, C. distans. 



6. Dark-gray splintery shale without hard bands. The 

 base of this zone is about fifteen yards west of the present 





