American Association. 278 



north-west of the one described, has been traced running paralle 

 with it for seven miles. If the form which has been attributed to 

 the first band be correct, the second would overlie it, with a great 

 mass of gneiss between. A third, band of limestone occurs about six 

 miles north of the second; this has been traced for about four miles 

 running east, which would be nearly parallel with the bearing of 

 the second. In this bearing it has not yet been followed farther 

 than to within a short distance from the line between the Seig- 

 niory of Argenteuil and the township of A.bercrorabie, towards 

 the rear of both. 



Continuous exposures of limestone have been met with on 

 the west side of the Riviere du Nord at St. Jerome. They 

 have been followed for two miles with a north bearing, and. the 

 strike of the stratification between Saint Jerome and the re9,r of 

 Abercrombie, is such as to make it probable that the St. Jerome 

 rock will ultimately prove to be a part of the third band. A 

 feature common to both localities is the occurrence immediately 

 near the limestone, of immense masses of lime feldspar. North of 

 the Argenteuil band, eight miles, examined across the stratification, 

 consist almost entirely of it, in the form of labradorite, of which 

 masses of the opalescent variety are in some parts enclosed in a 

 paste of the mineral without any play of colors, these feldspars 

 are accompanied with hypersthene and ilmenite. This felspar 

 .rock is abundant at St- Jerome, and its stratified character is con- 

 spicuously displayed, the beds running parallel with the hmestone. 



Mr. Hunt has traced a band of crystalline limestone for eleven 

 miles, running diagonally across the township of Rawdon in a 

 north bearing. On the wesr. side of this, lime-feldspar forms the 

 great bulk of the rock exposures for twelve miles across the 

 measures, and shows a well-marked stratification. It appears 

 probable that the Rawdon calcareous band is the same as the St. 

 Jerome band, and that a synclinal axis exists between the two, the 

 turn of the calcareous band on which is covered up by the fossi- 

 liferous rocks to the south. 



In Chateau Richer below Quebec, a band of limestones occurs 

 about a mile from the fossiliferous deposits, and to the northwest 

 of it lime-feldspars present, a breadth of eight miles. On an 

 island near Parry's Sound on Lake Huron, Dr. Bigsby observed 

 the occurrence in situ of the opa'escent variety of labradorite, and 

 the name of the mineral remin Is us of the existence of the rock 

 beyond the eastern end of the province. It thus appears probable 



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