Grabau — Faunas of the Hamilton Group. 



233 



I STRATIGRAPHY OF EIGHTEEN-MILE CREEK AND 

 ADJACENT TERRITORY. 



The portion of Eighteen-mile creek here under discussion, lies between 

 the railroad bridge at North Evans station and the shore of lake Erie. (See 

 map, Plate I.) The distance between the two points in a straight line is 

 something over a mile, but the meandering of the stream has greatly increased 

 the length of the gorge. Eight sections are exposed, no two extending in 

 the same direction, and therefore no two showing the same dip of the strata. 

 The true dip is between one and two degrees to the south-west. 



There are six sections along the lake shore which exhibit the strata of 

 the Hamilton group ; five north and one south of the mouth of Eighteen- 

 mile creek. These are : 



1. Bay View cliff. 



2. Athol Springs cliff. 



3. Erie cliff, including the sections on Avery's creek. 

 •A. Wanakah cliff. 



5. Idle wood cliff. 



6. South shore cliff, No. 1. 



These are described below with those of Eighteen-mile creek. The 

 following formations are exhibited in the sections (See also diagram, 

 Plate II): 



Chemung group 



Hamilton group 



Portage stage 



Hamilton stage 



Marcellus stage 



Naples shales 

 Genesee slate 

 ^ Moscow or upper shales 

 ^ Encrinal limestone 

 | Hamilton or lower shales 

 Transition shales 

 Marcellus shales. 



Chemung Group-- Portage stage. 

 Naples shales. 



The term "Naples shales" was proposed by John M. Clarke in 1885, for 

 the shales and arenaceous beds lying between the Genesee shales and the 

 Portage sandstones ; * that is, for the beds carrying the peculiar Naples fauna. 



• Bull. 10 U. S. Geol. Surv., p. 36. 



