REPORT OP THE STATE PALEONTOLOGIST 1902 1185 



9 The Leperditia bed, about 25 inches thick, forms the roof in 

 most of the underground cement workings. It is a persistent 

 band of tough black shaly limestone, and is full of the shells of 

 Leperditia alta, which show plainly on the gray weath- 

 ered surfaces of the thin layers into which this formation splits. 

 The Leperditia bed is well exposed in the hanging wall of the 

 several quarries on the Glory hole vein along the eastern slope 

 of the Vlightberg, and also at the old cement opening on the hill- 

 side over the White lime quarry on the North hill. At the latter 

 point the following species were obtained : Leperditia alta 

 (aa), Beyrichia sp.? (aa), Modiolopsis dubius 

 Hall, and Spirifer vanuxemi. 



10, 11 Above the Leperditia bed are two bands of yellowish 

 limestone, aggregating 7 feet, 7 inches in thickness, which break 

 up into polygonal blocks [see pi. 6] formed apparently by shrink- 

 age cracks similar to those seen in drying mud, and this resem- 

 blance is rendered more striking by the concave plates into which 

 the blocks readily split along planes parallel to the stratifica- 

 tion. Local names are given to different portions of these two 

 beds, which might perhaps more properly be considered as a 

 single formation. The lower 22 inches is called the " streaked " 

 because of its horizontal dark lines ; the " prismatic " or " five 

 point," 32 inches thick, breaks up into mostly pentagonal blocks 

 4 to 6 inches in diameter; the "paving block" or "mud crack," 

 15 inches thick, breaks into larger polygonal blocks of 6 to 10 

 inches diameter; and an uppermost 24 inch layer consists of 

 gray weathering impure silicious limestone. Portions of these 

 two beds make good cement but as a rule they are not quarried 

 because the rock above them does not form a safe hanging wall 



or roof. 



Manlius limestone 



Beds 12-19 

 The Manlius limestone, aggregating about 42 feet in thick- 

 ness, consists of eight beds of generally black or bluish gray 

 limestone, with many intercalated thin beds that weather to a 

 light gray. The lower beds, 12 to 16, contain the species so 

 characteristic of the Manlius fauna: Leperditia alta, 



