MINERAL RESOURCES OF THE STATE OF NEW YORK 43 



a careful study of the Rondout section and established the strati- 

 graphic relations which are exceedingly complicated by the intense 

 folding and faulting. In that locality 9 distinct cement layers or 

 beds are encountered, with an aggregate thickness of 30 feet. 



At Howes Cave, Schoharie county, there is a great development of 

 limestones which include members of the Helderbergian and Ca3aigan 

 groups, ranging from nearly pure calcium carbonate rocks to argil- 

 laceous strata with considerable magnesia. The natural cement 

 rock occurs in the lower part of the section and belongs to the Ron- 

 dout formation. It carries about 75 per cent of carbonates, of which 

 20 per cent is magnesium carbonate; the rest is silica, alimiina and 

 iron oxides. 



In central New York natural cement rock has been quarried in 

 Madison and Onondaga counties where it is found near the top of the 

 Manlius formation of the Silurian. The quarries are located near 

 Manlius, Jamesville and Fayetteville and at one time supported a 

 thriving industry. The rock occurs in two layers each about 4 feet 

 thick. 



Cement quarries at Buffalo, Falkirk and Akron, Erie county, once 

 ranked second only to those in the Rosendale district in quantity of 

 product. The limestone is the Bertie at the top of the Salina series 

 and the workable thickness ranges from 5 to 8 feet. 



Industrial development. The first experiments in the manufacture 

 of natural cement are recorded as having been undertaken in Madison 

 county during the construction of the Erie canal. They resulted 

 from the discovery that certain limestones when calcined did not 

 slake on addition of water, but after grinding the same material 

 developed hydraulic properties so that it could be employed under 

 water. The quarry from which the limestone used in the experiments 

 was taken is said to have been situated on the lands of T. Clarke, 

 in Sullivan township, Madison county. The product of the first 

 efforts at cement making was employed in the locks and walls of the 

 Erie canal in the years 1818 and 18 19, and soon after a patent was 

 taken out on the basis of this discovery by Canvass White. The 

 Legislature of the State of New York purchased the patent rights for 

 manufacturing the cement in the State in 1825 for the use of the 

 citizens. 



Cement works were established in the Kingston district soon after 

 the original developments in central New York, probably about 1825 ; 

 the industry here was favored by natural advantages for manufactur- 

 ing and marketing the product and it rapidly attained importance. 

 By 1840 there were 16 plants with a total of 60 kilns engaged in the 



