RAYMOND: 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 yet fully determined. Professor ° 
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 the 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 Cryptolithus tessellatus is common, associated with Ceraurus 
pleurexanthemus, Calymene, Sinuites, Plectambonites, and Dalmanella. 
About 100 feet above this zone, hemispheric bryozoans are common, 
and with them are Parastrophia 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 layers 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 layer 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) stevensoni 
Grabau, Byssonychia walkerensis Grabau, B. radiata (Hall), and other 
pelecypods and brachiopods. This fauna is generally considered to 
be of Upper 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 Upper 
Chazy and Black River. Since the Normanskill graptolites occur in 
the lower part of the formation, they would probably be of Upper 
Chazy age. 
