The Apatite Deposits of Canada. 67 



years, been found to contain deposits of apatite of economic im- 

 portance; one in the province of Ontario, in which the above 

 observations were made by the writer previous to 1866, including 

 parts of the counties of Lanark, Leeds, and Frontenac ; and the 

 other, since made known, in the province of Quebec, chiefly in 

 Ottawa county. In both cases it is found in the rocks of the 

 Laurentian series, consisting of granitoid gneisses with bands of 

 quartzite, of pyroxenite, and of crystalline limestone. These 

 ancient and highly inclined strata, with a northeast strike, rise 

 from beneath the horizontal paleozoic rocks near Kingston, and 

 again pass beneath them near Perth. These overlying strata 

 belonging to the Ottawa basin, hide, moreover, to the eastward, 

 the apatite-bearing gneisses of this district ; which, a short dis- 

 tance to the westward, are again concealed by the Taconian and 

 other overlying pre-Cambrian groups in Hastings county. The 

 gneissic belt is here seen chiefly in the the townships of Lough- 

 borough, Storrington, Bedford, North and South Crosby, and in 

 North Burgess, where the apatite was first discovered. 



The country presents a succession of small, isolated, rounded, 

 rocky hills, alternating with numerous small lake-ba- ins, hollowed 

 out of the gneiss, and sometimes out of the interstratified lime- 

 stones ; the general trend both of the hills and the lakes being 

 coincident with the strike of the rocks. These, though concealed 

 in the valleys by considerable depths of alluvial soil, are seen in 

 the hills to be hard and undecayed. These geographical features, 

 as I have elsewhere pointed out, wer apparently determined by 

 sub-aerial decay previous to the erosion wnich removed from 

 them the softened and disintegrated portions, leaving the present 

 outlines.* 



When, after cutting the forest-growth which covers these hills 

 of granitoid gneiss, fire is allowed to pass over the surface, des- 

 troying the undergrowth, the comparatively thin layer of soil is 

 laid bare and is soon washed away by the rains; leaving the bald 

 rocky strata exposed in a manner singularly favorable lor geologi- 

 cal study, but rendering the region sterile. To prevent this pro- 

 cess of denudation it has become the practice in some parts of the 

 country, after burning over the hillsides, to sow them, without 



* See the author's paper on "Rock Decay Geologically Considered." — 

 Amer. Jour. Sciences, Sept., 1833. 



