﻿GEOLOGY OF THOUSAND ISLANDS REGION 1 73 



Small masses of barite are not infrequent in the Grenville lime- 

 stone, but none were seen of any size or importance. An old 

 opening was made on a coarsely micaceous limestone contact zone, 

 2 miles north of Theresa, but no mica of merchantable size and qual- 

 ity was forthcoming. 



The only mineral industry of the district that has any present or 

 prospective value is the quarry industry. Stone has been and is 

 being quarried for road metal, for paving, for flagging, for lime, 

 and for construction. Various Precambric rocks, the Potsdam 

 sandstone, and the Pamelia, Lowville and Black River limestones 

 have all been quarried in varying degree for one or the other of 

 these purposes. 



Road metal 



Road improvement is going on hereabout, as elsewhere in the 

 State. About Theresa, Grenville limestone has been chiefly used, 

 though a small quarry has been opened in very impure limestone 

 cut up by granite, which furnished very variable, and hence not 

 very good material. The limestone from the other quarry makes a 

 very good macadamized road, as would apparently much of the 

 Grenville limestone of the district. 



About Alexandria bay various experiments have been tried with 

 road metal. The Laurentian granite gneiss of the vicinity has been 

 used, and of course given poor satisfaction. To a small extent 

 Pamelia limestone has also been used, and has not proved very 

 satisfactory, probably because of the variability of the different 

 layers used, pure limestone and magnesian limestone probably being 

 mixed together. At present a considerable stretch of road north 

 of Browns Corners is being macadamized with Grenville amphib- 

 olite, obtained I mile west of Redwood, surfaced with Grenville 

 limestone, which, as we saw it being obtained, was of poor qual- 

 ity. The amphibolite was slightly soaked with, and cut by granite, 

 so that the material was not as uniform as is desirable, but the 

 quantity of granite is so slight that the lack of uniformity is not 

 prominent, and the amphibolite itself is quite undecayed, firm and 

 strong. It seems on the whole likely to prove quite adaptable to 

 road-making purposes. Its composition is quite similar to that of 

 trap, and in all probability it will bind in similar fashion. 



Potsdam sandstone has been used as a road rock to a small ex- 

 tent. It is absolutely unfitted for such use, and the worst rock that 

 could be selected for the purpose. 



