Grabau — Faunas of the Hamilton Group. 



237 



Transition Shales. 



Thirty feet of the shale beneath the Strophalosia bed must be regarded 

 as transitional between the Marcellus and the Hamilton, containing an 

 intermixture of the fossils of both. Several courses of concretions are present 

 in these shales, but fossils are not very abundant. 



Upper Marcellus shales. 



Only about fifteen or twenty feet of the upper Marcellus shales are 

 exposed in the sections along the lake shore. The shale is uniform in texture, 

 well laminated and brittle. Fossils are rare, consisting mainly of Tentaculites 

 gracilistriatus and Styliolina fisswrella. In the upper part of the mass, these 

 are extremely abundant, in some places thickly covering the weathered surfaces 

 of the shale. Lunulicardium fragile also occurs occasionally, and carbonized 

 plant remains are sometimes found. Several hard calcareous layers contain- 

 ing Amboccelia umhonata occur in the upper part of the mass. 



The lower beds of this group, i. e. the black Marcellus shales, have not 

 yet been examined and their description will be deferred to a future paper. 



Description of the Sections. 



Bay View cliff. This is the first cliff on the lake Erie shore south of 

 Buffalo. It rises nowhere above fifteen feet, and exposes only the upper 

 Marcellus shales. The jointing characteristic of all the shales in this region 

 is well shown. The total length of the section is a little less than half a mile. 



Athol Springs cliff. This cliff extends southwards from the Fresh Air 

 Mission to Mann's point, a distance of about three-fourths of a mile. Its 

 average height is about thirty feet, of which about fifteen feet near the 

 northern end are of Marcellus shale. The cliff for some distance south of the 

 Mission attains only about one-half its usual height, and the top is formed 

 by hard layers of the Marcellus. These hard layers dip below the lake level 

 near the southern end of the cliff, beyond which point the cliff presents only 

 the transition beds. In a few places near the top of the cliff the Strophalosia 

 bed appears. This cliff is separated from the next by a dry ravine, in which 

 exposures are few. 



Erie cliff. This cliff, beginning on the land of Mr. Avery, extends 

 southward for a distance of about one and one-half miles. It rises nowhere 

 much above thirty feet, and near the southern end it is much lower. The 

 ravine of Avery's creek cuts it in two, and furnishes additional sections for 

 observation. Twenty-six feet above the base of the cliff, the Strophalosia 



