IRON ORES OF THE CLINTON FORMATION 55 



set in the trench. The overburden consists of lo feet or slightly 

 more of limestone, somewhat shaly toward the top, and about 

 the same thickness of soil and glacial material. It is loosened 

 for the shovels by drilling and blasting. The 6-inch holes made 

 by churn drills, extend into the ore for about 3 inches and are 

 16 feet apart, the first row being 6 feet from the edge of the 

 trench. A layer of limestone, 15 to 18 inches thick, that remains 

 on the ore has to be removed by hand. The ore is then 

 loosened by blasting, after holes 3 feet apart and extending a 

 few inches into the underlying green argillaceous limestone, have 

 been made by steam drills. A small amount of the limestone 

 sometimes adheres to the ore but is readily removed. The ore 

 is broken by sledges into convenient size for handling, after 

 which it is loaded, by means of a 40-ton steam shovel, into the 

 buckets of a derrick and hoisted into cars for shipment. A spur 

 from the Rome, Watertown & Ogdensburg Railroad extends 

 along the trench on the side opposite the spoil bank; it is moved 

 back from time to time with the advance of operations toward 

 the south. 



The Fair Haven Iron Co. has pursued a similar plan in opening 

 the property at Sterling Station. The rock is here mostly shale, 

 so that its excavation presents less difficulty than the limestone 

 farther west. Instead of wasting the material in the abandoned part 

 of the workings, the shovel loads into cars which run out on a 

 track at one end and are dumped to the north of the pit. The shale 

 and soil covering has a thickness of from 10 to 20 feet. The 

 material is loosened by blasting in advance of the shovel in tlic 

 manner above described. 



The mines at Clinton furnish the only examples of underground 

 exploitation of the ores in the State. The long-wall method is 

 employed, the same as used in many coal mines. This method admits 

 of complete extraction of the ore in one operation. It is particularly 

 adapted to comparatively thin deposits that have a flat dip. En- 

 trance to the workings may be had either through a shaft, or, if 

 the seam outcrops anywhere, through an adit driven on the level. 

 By taking advantage of the surface features, it has been jiossiblc 

 at Clinton to follow the ore from its ontcrop and to make use (^f 

 the slight inclination of the beds in securing natural drainage. The 

 main entries or gangways are run in an easterly or northeasterly 

 direction across the dip. From these, branches turn off at every 

 100 feet to the working face, which is kept a short distance ahead 



