Granites, Syenites and Gneisses. 35 



Grindstone Island, Jefferson County. — A red granite is quar- 

 ried extensively on this island in the St. Lawrence river, north-west 

 of Clayton. There are many outcrops, especially on the western side 

 of the island, and small quarries have been opened at more than 

 twenty different points. Three of them are large and worthy of 

 notice here. 



Gordon's Quarry is about a half a mile from the north-west side 

 of the island. There are two openings, at the east and west ends re- 

 spectively, of a low, rocky ledge, which rises twenty feet above the 

 surrounding surface and sixty feet above the river. On the west 

 paving blocks are made ; on the east a large part of the stone goes 

 into buildings. The vertical joints run nearly north and south, and 

 are used in blasting apart the great blocks of stone. Afterwards 

 these blocks are split by plug and feather wedges. As the stone 

 splits true, and blocks of large, rectangular shapes are readily got, it 

 makes an excellent heavy-wall stone. And it is used for massive 

 foundation work. The stone is red and coarse-crystalline. It is 

 worked for the International Granite Company of Montreal. The 

 stone are shipped by boat down the St. Lawrence. 



The Chicago Granite Company's Quarry is on a north-west 

 facing hill side, about 1,000 feet from the bay and river, and in a 

 great rounded ledge of rock. The excavation has a length of 100 

 yards from north to south, and at the most is not more than forty 

 feet in depth. It is all above natural drainage. The seams or joints, 

 dividing the rock, appear to be irregular and not continuous. The 

 stone splits most readily in planes which dip to the eastward. It is 

 red, mostly coarse-crystalline, but varies in texture from point to 

 point. Imbedded and rudely spheroidal masses of a gray, granitoid 

 rock, of much finer grain, occur in the red granite, and are here 

 known as "knots." This quarry has been opened for five years. 

 The output has been nearly all in the form of paving blocks, and has 

 been sold to western cities. A tramway, 1,000 feet long, connects the 

 quarry with the wharf, at which there is a mean depth of twelve feet 

 of water. 



The Thousand Island Granite Company's Quarry is on the 

 point of a rocky promontory which projects north-west into the river, 

 and is on the northwest side of the island. It is at least a quarter of 

 a mile east of the Chicago company's quarry, and is in a rocky knob, 



