'2 6^ THfi PROBABLfi StJBDlVlSlO^ 6W 



at angles varying from about 50 to 70 degrees. Attaining the reaf 

 of the township, a distance of about ten miles, the two bands unite,' 

 and are found really to constitute but one, the thickness of which, a» 

 far as I can make it out, is from 500 to 1,000 feet. It is plain from 

 this distribution that the Hmestone is part of the out-^crop of an un- 

 dulating sheet, the ridges of which have been worn down. But in 

 the horizontal section of an undulating surface, similar forms in the 

 distribution of the' rim, may be derived from the anticlinal or syn-- 

 clinal part of the undulation, and as the dips on the opposite sides- 

 are both one way, it is a' question to which part the' area belongs. 

 Within a short distance of the eastern side of the limestone,— -in fact 

 touching it in one place,— an intrusive syenite makes its appearance 

 belonging to a mass which occupies about thirty square miles in the 

 townships of Grenvitte and Chatham, and runs to a point in Went- 

 worth. The intrusion of such a mass of igneous rock can 

 scarcely fail to have had a considerable effect in modifying the atti- 

 tude of the strata which surround it. The crystalline condition of the 

 syenite shews that it was slowly cooled under great pressure, and we 

 cannot now say whether it was a deep-seated part of an outburst which 

 reached the surface, as it was then constituted, or whether it was ori- 

 ginally overlaid by masses of gneiss and limestone, which have since 

 been worn away. In either case the probability is, that it would give 

 to the strata,- now surrounding it, an anticlinal form. It seems pro-- 

 babie, therefore, that the western: dip, belonging to the eastern band 

 of limestone, where it approaches the syenite, is a true one, and that 

 the form between the bands is synclinal. This appears to be cor- 

 roborated by the fact that where transverse valleys occur between 

 them, the wearing down of the intermediate gneiss widens the cal- 

 careous bands, particularly the east one, and narrows the interval. 



The calcareous sheet having, thus the form of a trough, the west- 

 ern dip of the Western out-crop must be an over turn ; and two spurs 

 of the rock which point out to one another, the one turning south 

 from the western bfelt, and the other north from th'e eastern, must 

 constiturte a subordinate anticlinal. "Without reference to minor 

 corrugations, the general form of the area would be that of two- 

 troughs joined together, each about a mile and a half wide, with an 

 overturn dip on the west side, the one trough running north and 

 south, and the other, as far as unconcealed by the superior fossilifer- 

 ous strata, south -south -west and north-north-east. The opposite 

 sides of this calcareous trough run into two valleys, which unite atits- 

 ii,orthern extremity. But though the limestone then crops out, the 



