482 C. R. STAUFFER 



Hamilton beds have been divided, in descending order, into the 

 Ipperwash limestone, the Petrola shale, the Widder beds, and 

 the Olentangy shale. In the sections at Arkona, Lambton County, 

 the two lower stages are well exposed. At no place in the province 

 is the bottom of the Olentangy shale exposed, although well- 

 records indicate that it rests directly upon the Delaware limestone. 

 This latter formation is well shown in the excellent outcrops at 

 St. Mary's and at several places in the vicinity of Brussels and 

 Goderich. In the following section of the Hamilton beds in Rock 

 Glen at Arkona, only the fauna of the Encrinal limestone and of the 

 beds below are given, since the subsequent comparison is made 

 with those portions of the section only. 1 



Section of the Hamilton Rocks at Arkona, Ontario 



Widder Thickness 



Beds Ft. In. 



1 1 . Soil and drift 15 o 



10. Limestone, argillaceous, massive, blue, partly cystalline, alter- 

 nating with thin layers of shale. These beds form the falls at 



th e old mill 10 8 



9. Shale, soft, blue, with calcareous nodules or concretions 8 4 



8. Limestone, argillaceous, blue 1 6 



7. Shale, usually soft, blue, but some layers harder and more 



massive 17 5 



6. Shale and shaly blue limestone 7 o 



5. Coral zone. A decomposed blue or gray shale, often an impure 



shaly limestone, filled with corals 3 6 



4. Encrinal limestone. A hard, pyritiferous, bluish-gray limestone 

 which is full of crinoid segments, coral fragments, and other 

 fossils. It includes some brownish shale near the base 2 4 



FAC NA 



Aulopora serpens, Ceratopora dichotoma, Cladopora canadensis, 

 Cladopora roemeri, CraspedophyUum archiaci, Cystiphyilum 

 vesiculosum, Favosites alpenaensis, Favosites placentas, Favosites 



turbinatus, HeliophyUum halli, Syringopora intermedia, Syringo- 

 pora nobUis, Traehypora elcgantula, Zaphrentis prolifiea, Dola- 

 tocrinus liratus, Hedcrella filiformis, Streblotrypa hamiltonensis, 

 Taeniopora exigna, Ambocoelia umbonata, Airy pa reticularis, 

 At/iyris vittata. Chonetes coronal us, Chonctes lepidus, Delthyris 



1 The fauna of the other beds may be found listed in the Geological Survey of Ccuiada 

 Memoir (No. 34, p. 164), on the Devonian of southwestern Ontario. 



