BLUESTONE AND OTHER SANDSTONES 



9 



ditious change, and the rough streak may become as workable as 

 the balance of the bed, and again it may increase in size, spoiling 

 the bed entirely. 



Xearly every quarry has its ow n peculiar formation. Quarries 

 within 400 or 500 yards of each other frequently differ greatly 

 as to quality and formation. 



Stripping 



The overburden, or M top," consists in Ulster county of a 

 layer of soil, clay or hardpan, underneath this alternating beds 

 of shale and rock. This ki rock " is a name given to the part of 

 the ledge which can not be worked into salable stone. (" Rock " 

 also is a term applied to the thick " lifts " of stone which are 

 sold to the mills for sawing and other treatment.) Below the 

 shale and the rock is the bed of stone. The thickness of the 

 soil, shale, rock and bed of stone is very variable. But a rough 

 ratio for profitable quarrying is 1 of bed to from 2 to 3 of top, 

 depending on the ease with which the stone is worked, its 

 quality and the character of the bed. Some quarries have all 

 soil top, some all rock, and again some have all shale top. 

 Generally all three are found except in Delaware and Broome 

 counties, where shale occurs rarely. 



The stripping is usually carried on in winter, as only a few 

 quarries can be worked when it is very cold, owing to the effect 

 of freezing on the durability of the stone. The ground also is 

 then frozen hard, and the scales of dirt are quite firmly cemented 

 by frost. Dynamite or some other high explosive is used to 

 loosen the rock and dirt. This is found to be better and more 

 economical of time and labor, since the frozen dirt and slate can 

 be handled better than when uncemented. The stripping is 

 handled by shovels and wheelbarrows for the soil and shale, 

 while powder and dynamite are employed in breaking up the 

 rock. There is not much difference in cost of removing the vari- 

 ous kinds of " top " except as to thickness. Rock is easily han- 

 dled with a derrick after blasting. Hardpan requires consid- v 

 erable work even after blasting. Shale and soil require a great 



