304 



INDEX TO THE STRATIGRAPHY OF NORTH AMERICA. 



Ontario and west of Cayuga Lake. Similar accounts with local variations are given 

 in the reports of Vanuxem *^® and Mather.^''^ 



With reference to the Hamilton as exposed on the southeastern shore of Lake 

 Erie, Grabau "" may be consulted. He gave the following classification: 



The following formations are exhibited in the sections : 



Chemung group (Portage stage) : 

 Naples shales. 

 Genesee slate. 

 Hamilton group: 

 Hamilton stage: 



Moscow or upper shales. 



Encrinal limestone. 



Hamilton or lower shales. 

 Marcellus stage: 



Transition shales. 



Marcellus shales. 



The Hamilton of Cayuga Lake, New York, was made the subject of a special 

 study with reference to its fauna by Cleland,"" who states: 



The Hamilton formation, including the Marcellus shales, is in this region, as shown by the 

 Ithaca well section, 1,224 feet thick. It is bounded above by the Tully and below by the Onon- 

 daga (Corniferous) limestone. 



Cleland divided the Hamilton of the Cayuga section into 25 faunal zones, each 

 of which is described in detail in his report, together with the composition of the 

 faunules. 



Williams's later studies in classification^'^' ^^^ led him to the following arrange- 

 ment of the Ithaca section: 



Revised classification and nomenclature of the section passing through Ithaca, N. Y. 



a In the chart as published in Science (vol. 24, p. 366) this figure is 300 feso. 



