58 GEOLOGY OF ERIE COUNTY 



No line of contact can be distinquished between the Dunkirk 

 shale and the Gardeau shale above. They merge gradually, the 

 transition in Big Indian creek being through a succession of 

 thin, black layers, alternating with light gray, iron stained 

 layers. 



The Dunkirk shale forms the cliffs along the southern and 

 western sides of Dunkirk harbor and the cliffs west of Point 

 Gratiot. The whole formation is exposed in Big Indian creek 

 and in the cliffs along Cattaraugus creek at Versailles. The 

 exposure in Big Indian creek begins just below the bridge on the 

 Hanover Center road in an alternation of thin, black shales and 

 gray shales, above which are pinkish shales of the Gardeau 

 formation. Below these transition shales appear beds of black, 

 hard shales with strong cleavage planes and these continue 

 downward with alternate beds of more fissile black shale and 

 thin sandstones. The thickest of these forms a cascade fifteen 

 feet high. The contact of the Dunkirk and Hanover is exposed 

 at the mouth of the creek. Here the lowest bed of the Dunkirk 

 is a mass seven feet thick of hard, black shale iron stained 

 after exposure and splitting into very large, thin laminae. 

 Underlying this is a bed of olive gray shale containing nodules 

 the size of a pigeon's egg or smaller. This breaks into lumps 

 rather than into laminae. As this nodular shale occurs 

 throughout the Hanover shale there seems no doubt that this bed 

 constitutes the upper bed of the Hanover. 



The Dunkirk shale is exposed in a gully that runs eastward 

 from the state road at North Collins. It forms a cliff along the 

 southern branch of Eighteen Mile creek just north of Clarksburg. 

 It crops out at the heads of the gullies east of North Boston, and 

 forms a fall at Colden on Cazenovia creek. The concretionary 

 layer is at the lake level at Van Buren Point, crosses Big Indian 

 creek, causes a rapid in Cattaraugus creek at Versailles and 

 shows in the cliff at Colden. 



No fossils have been described from the Dunkirk shale. 

 Plant remains are abundant in all its exposures. 



