2 14 NEW YORK STATE MUSEUM 



In this section no Ithaca fossils appear, but the Naples fauna ranges 

 throughout, that is to say that, while in the Naples section this fauna 

 ranges through only 626 feet, in the Genesee river section it persists through 

 about twice that amount, or 121 1 feet, before the incoming of the 

 brachiopod fauna from the east, which is here distinctly Chemung. It 

 has been shown by D. D. Luther 1 that the original Portage sandstones 

 in this section are equivalent to and continuous with the Highpoint sand- 

 stones in the Naples section carrying a fully developed Chemung fauna. 

 These noteworthy differences in the distribution of the fauna in these two 

 sections show definitely two facts, first that the Naples fauna came in from 

 the west, second that the Ithaca-Chemung or brachiopod fauna spread 

 westward from central New York. 



Lake Erie section (Erie and Chautauqua counties). At the bottom of 

 the section 



Feet 



i Middlesex black band --------- 6 



2 Cashaqua shales ----- . 32 



3 Rhinestreet black band -------- 227 



4 Silver Creek and Angola soft light sandy shales with few flags 257 



5 Dunkirk black band --------- 58 



6 Portland light colored shales and thin flags - 282 



Above this total of 868 feet comes in the Chemung brachiopod fauna 

 represented in a sandstone 22 feet in thickness, termed by James Hall the 

 Laona sandstone, exposed at Laona, Forestville, Brocton, etc. Comparison 

 of this section with the others shows, as we have already pointed out, the 

 very notable increase of the black shales toward the west and the rapid 

 decrease of sands the farther we get away from the emerging shore at the 

 east. An examination of the fossils shows the prevalence of many species 

 in the beds above the heaviest black band which exist neither in the 

 Cashaqua shales at the bottom nor in the development of the shaly beds 

 in eastern sections. These constitute the body of the fauna characterizing 

 the Chautauqua subprovince. 



1 N. Y. State Mus. Bui. 52. 1902. p. 616. 



