764 NEW YOEK STATE MUSEUM 



The attenuated eastern extension of the great Salinl: forma- 

 tion is of variable character and thickness and may not be con- 

 tinuous throughout. Locally it consists of heavy beds of cement 

 rock but generally it is composed of thin beds of more or less 

 impure cement intercalated with thin bedded limestones of vary- 

 ing character. 



'^ The cement beds attain their greatest development around 

 Kondout and Rosendale, where they are extensively worked. 

 The cement rock is a blue black, very fine grained, massively 

 bedded deposit of calcareous magnesian and argillaceous ma- 

 terials and is of somewhat variable character and composition. 

 The rock produces a cement of good quality only when the 

 components bear certain relative proportions to each other. 

 A characteristic feature of the rock is the light buff hue to which 

 it weathers on the surface. At Rosendale there is a 21 foot bed 

 of the cement at the base of the formation^ then from 12 to 15 

 feet of mixed impure cement and limestone beds, then another 

 cement bed 11 feet in thickness. Above these are the Tentaculite 

 and Pentamerus. 



These cement beds with some variations in thickness, and 

 many in character, extend over a wide area from north of White- 

 port through Rosendale to beyond Highfalls, outcropping in a 

 belt about eight miles long and two and a half Avide. At High- 

 falls there is an upper bed of cement, 15 feet thick and a lower 

 bed 5 feet thick, separated by 3 feet of impure limestone. At 

 Whiteport the upper cement bed is 12 feet thick, the lower from 

 15 to 20 and the intervening limestone 10 feet in thickness. 

 How far they may extend under the overlying rocks to the west- 

 ward is not known, and their southern termination has not been 

 explored. To the northeast the cement thins out rapidly and 

 gives place to impure cements and limestones, but it thickens 

 again rapidly in the Rondout region. At Rondout there are two 

 cement beds, the lower one is 22 feet thick and the upper 5 feet 

 thick, with 3 feet of limestone and cement intervening. ISTorth- 

 west the lower cement bed thins. 



In Onondaga county the cement beds are again prominent, and 

 vary in thickness from 1 to 5 feet. Many of the quarries show 

 two beds.'' 



