GUELPH FAUNA IN THE STATE OF NEW YORK 15 



the village and in a ravine south of Middleport. The layer may be differ- 

 entiated at the falls in Oak Orchard creek. 



Stratum 2 is composed of varying proportions of hard, dark gray, sub- 

 crystalline limestone and irregular beds of unstratified bluish hydraulic 

 material, giving the whole a dappled appearance. It is dark blue when 

 fresh but weathers a very light gray. It is also known in the canal south 

 of Lockport and in the creek 2^ miles-southwest of Gasport. Stroma- 

 toporas are common in it. The horizon can be recognized at Shelby from 

 the piles of material just west of the village. 



Stratum 3 is a compact, light brown dolomite of uniform texture. At 

 Niagara Falls there are small corals (Enterolasma caliculus, Favo- 

 sites) in the lower part. From the character of the rock and that of the 

 overlying stratum we regard this as the horizon of the lower Guelph fossils 

 at Shelby. There the subdivision into separate beds is more pronounced 

 and the fossils are restricted to a 3 foot layer ; this subdivision of the 

 stratum is also shown at Lockport where the layer is the highest and most 

 southern one exposed on the canal. 



Stratum 4 is finer, harder and lighter colored than the layers above and 

 below and is filled with cavities. Near the top is a continuous row of chert 

 nodules which are bluish when fresh but become white on long exposure. 

 This layer is nearly in a plane with the crest of the American and Horse- 

 shoe falls. Fossils are extremely scarce but the exposure is unfavorable for 

 examination. Poleumita scamnata occurs here, a species not else- 

 where found except in the chert nodules of the upper Shelby and Rochester 

 horizon. This fact indicates that this chert layer represents the upper 

 Giielph horizon which would, thus, be separated from the lower horizon by 

 an interval of 20-25 feet, considerably less than at Shelby. 



Above stratum 5, consisting of brownish dolomites in thin layers hav- 

 ing black partings, there is a covered interval of 10 feet (6), which is fol- 

 lowed by a 25 foot mass (7) of rough geodiferous dolomite in thick and 

 thin layers. This is exposed in the cut of the Gorge road south of the car 

 barn, at the south of Goat island and on the Three Sisters. This rock 



