K-wmond: correlation of the ordovician strata. 237 



permit of exact subdivision or correlation. In this section, the lower 

 500 feet or thereabouts appear to be of Trenton age, while the re- 

 mainder of the strata are probably Eden and Maysville, but where to 

 draw the line between the two is not vet fullv determined. Professor 



K t. 



Powell is engaged upon a further study of the section, and will soon be 

 able to give more detailed information. 



The lower 100 feet of the part of th^ Sevier referred to the Trenton 

 consists chiefly of shale, and its fossils are Calymene, Dalmanella, 

 and Rafinesquina. The next 125 to 150 feet consist of alternations 

 of thin-bedded limestone and shale, the latter predominant. In this 

 zone Crypfolithiis tcsseUatus is common, associated with Ceraurus 

 pleurcxanthemus, Calymene, Sinuites, Plectambonites, and Dalmanella. 

 About 100 feet above this zone, hemispheric bryozoans are common, 

 and with them are Parasfrophia hemiplicata, Dinorthis, and Sinuites. 

 The Parastrophia is not the pauciplicate form found in the Lower 

 Trenton of New York and Quebec, but like the form in the Middle and 

 Upper Trenton of Ontario. In this same zone Professor Powell found 

 some graptolites which appear to be Lasiograptus eucharis, a Middle 

 Trenton and Utica graptolite in New York. The upper 100 feet of 

 the strata here referred to the Trenton consist almost entirely of thin- 

 bedded blue limestone, and at the very top are great numbers of 

 Zygospira, Plectambonites, and Pholidops, while some laj-ers are full 

 of gastropods. 



The rocks above the Trenton consist principally of shale, becoming 

 more and more sandy toward the top. In the middle are some 

 massive calcareous strata, and an occasional laver of limestone is met 

 with at various horizons. The whole reminds one very much of the 

 Lorraine of New York, and the fossils emphasize that impression. 

 The upper 100 feet, more or less, belongs to the Bays sandstone, and 

 has the typical fauna, Platystrophia (or Orthorhyncula) stcvcnsoni 

 Grabau, Byssonychia icalkercnsis Grabau, B. radiata (Hall), and other 

 pelecypods and brachiopods. This fauna is generally considered to 

 be of L^pper Maysville age. 



The section, as interpreted above, seems to place the Normanskill 

 definitely as post-Middle Chazy and pre-Trenton, the Athens and the 

 Tellico together occupying the position usually filled by the L'pper 

 Chazy and Black River. Since the Normanskill graptolites occur in 

 the lower part of the formation, they would probably be of Lpper 

 Chazy age. 



