105 



6 — This limestone consists of heavy beds separated 

 by shale partings. Some of the characteristic fossils are: — 

 Ceratopora intermedia {Nicholson) 

 Athyris fultonensis {Swallow) 

 Leiorhynchus laura {Billings) 

 Spirifer mucronatus thedfordensis S. and G. 

 Stropheodonta concava {Hall) 

 7. — This shale is poorly exposed at the top of the 

 formation and appears to be nearly barren of fossils. 



Sections of the Hamilton Formation. 



The best localities for the examination of the strata 

 and for the collecting of fossils are as follows: — 



1. — Railway cut, one mile east of Thedford. 



2. — Gravel pits and Hunniford's fields north of cut. 



3. — The brick yards. 



4. — The valley of the Aux Sables river between Rock 

 Glen and Marshall's mills. 



Railway cut east of Thedford. — Fossils may be 

 collected from both sides of the railway cut east of Thed- 

 ford, but the best section is exposed on the south side. 

 The exposure here extends 25 feet (7-6 m.) above the road 

 bed, and consists of limestone and shale representing 

 the upper 15 or 16 feet (4-5 or 4-8 m.) of zone No. 5 and the 

 lower 9 or 10 feet (2 -7 or 3 m.) of zone No. 6. The lowest 

 beds of all are obscured, but crinoid remains were formerly 

 obtained from them. The fossils already listed for zones 

 5 and 6 occur in abundance particularly Spirifer mucronatus 

 thedfordensis S. and G., in the lower 10 feet (3 m.). 



Gravel Pits and Quarries north of the Railway cut. 

 — A short distance north of the railway cut, a shallow pit 

 in the overlying gravel has exposed the upper layers of 

 the section seen in the cut. 



The more common fossils at this point are: — 



Pentremites sp. 



Athyris fultonensis {Swallow) 



Cyrtina hamiltonensis Hall 



Eunella sp. 



Meristella sp. 



Pholidostrophia iowaensis {Owen) 



Stropheodonta demissa {Conrad) 



Platyceras sp. 



Phacops rana {Green) 



