The Classification and Distribution of the Hamilton and 

 Chemung Series of Central and Eastern New York. 



PART I. 



By Chaki.es S. Prosser. 



Contents. — Introduction ; Ithaca formation, p. 87 ; Annual New York Reports, p. 87 ; Final 

 New York Reports, p. 90 ; Views of more recent Contributors, p. 92. The Chenango Valley section: 

 The formations of Central New York, p. 94; Sangerfield and Madison, p. 90; Onondaga limestone and 

 Marcellus shale, p. 90: Hamilton formation, p. 90; Hamilton and Brooktield. p. 96; Smyrna, p. 100; 

 Sherburne, p. 123; North Norwich, p. 137; Norwich, p. 140; Oxford, p. 148; Greene, p. 150; Fenton 

 and Chenango, p. 154. The Unadilla Valley section : Columbus, p. 167; New Berlin, p. 170; Pittsfield, 

 p. 178. Geology of Southern Otsego county : New Lisbon, p. 180; Laurens, p. 190; Hartwick, p. 194; 

 Milford, p. 11>4 ; Maryland, p. 204. 



INTRODUCTION. 



Ithaca formation. — During the summer of 1895 the Ithaca formation, 

 with those immediately below and above, was carefully studied, proceeding 

 eastward from the meridian of the Chenango river valley until its fauna dis- 

 appears in Schoharie and Albany counties. A residence of nine years in 

 Ithaca made the writer well acquainted with the typical exposures and fauna 

 of this stage, while other investigations familiarized him with the same series 

 of deposits in southeastern New York and eastern Pennsylvania. The region 

 examined in 1895 had not been systematically studied in recent years, and it 

 proves t<> be one of the most interesting of the New York Upper Devonian. 

 However, before entering upon a systematic description of the characters and 

 distribution of the Ithaca stage, it will be well to review briefly the former 

 papers describing this formation. 



Annual New York Reports. — The name It// a r(t grmi/p^ was proposed by 

 Professor James Hall, in 1839, for a mass of rocks which consists of "alterna- 

 tions of shale, both slaty and compact, and argillaceous sandstone," typically 

 exposed at Ithaca. 2 xVt this time the underlying shales and argillaceous sand- 

 stones, which were later called the Portage group, had not received a name, 

 although they were recognized as constituting a group, and their stratigraphic 

 position was correctly indicated. 3 Professor Hall separated the Ithaca group 



1 In this review the nomenclature of the New York reports is followed. 



2 Third Annual Report, Fourth Geological District, New York (Assembly Doc. No. 275, 183!t>, page 318. 



3 Ibid., pp. 302-4, 314. 



