Grabau — Faunas of the Hamilton Group. 



239 



Idlewood cliff. This cliff extends from the drift filled gorge to the 

 mouth of Eighteen-Mile creek, where its height is about fifty feet. The 

 lowest beds exposed in this section are the shales beneath the Trilobite beds ; 

 the Pleurodictyum beds, though probably forming the base of the section, 

 being covered by talus. The Encrinal limestone appears near the top of 

 the bank, and above it are six feet of the Moscow shales. The total length 

 of the section is about a mile, though parts of it are obscured by talus and 

 vegetation. 



The Eighteen-Mile creek sections. These sections, undoubtedly the most 

 interesting and the ones most thoroughly studied, number eight in all, as 

 follows : 



Section A. This is the section which forms the left bank of the stream near 

 its mouth. The lowest strata exposed are the Trilobite beds. The Encrinal 

 limestone appears in the upper part of the bank, capped by about twelve feet 

 of the Moscow shales. The total height of the section is fifty-six feet, and its 

 length about one thousand feet. 



Section B. This section, on the right bank of the creek, has a length of 

 about twelve hundred feet, and a height of about fifty five feet. It exhibits 

 about thirty feet of the Lower shales, the Encrinal limestone, the Moscow 

 shales and part of the Genesee shales, including the Styliolina limestone. 



Section C. Only about nine feet of the Lower shales are exposed in this 

 section, which also exhibits the succeeding strata, including twenty-five feet 

 of the grey Naples shales. The section has a length of about seven hundred 

 feet, and a total height not exceeding sixty-two feet, (Plate III). 



Section D. The Sftropkeodonta demissa bed is the lowest exposed in 

 this section, and its characteristic fossils may be obtained here in abundance. 

 The Encrinal, Moscow, Genesee, and lower Naples beds form the upper part 

 of the section. The length of the section is 2200 feet, Near its upstream 

 end, a small fall is produced by the Encrinal limestone which extends across 

 the stream. 



Sections HJ } F and (J. From two to four feet of the Moscow shales are 

 exposed at the base of each of these sections, the upper portions being made 

 up of the Genesee and Naples shales. The sections are respectively six 

 hundred, five hundred, and three hundred and fifty feet in length. The 

 Conodont bed appears as a thin band just beneath the Styliolina limestone in 

 the last two of these sections. It does not form a stratum distinct from the 

 Styliolina band, but is united with it. 



