iqoo-i.] Physical Geology of Central Ontario. 147 



are found dipping north at less than one degree. On the south shore of 

 the lake other outcrops of limestone occur, with very light southerly dip. 

 To the north, the edge of the Cambro-Silurian escarpment, looking out 

 over the main body of the Archean, is found at a distance of about 11.5 

 miles (as measured on the maps). 



Is this the summit of a monadnock, buried when the sediments were 

 deposited, and since uncovered in the progress of denudation ; or have 

 there been granitic intrusions since the formation of the stratified 

 deposits ? In this locality positive evidence either way seems to be 

 lacking. 



Further east, just north of Varty lake, and four miles from the edge 

 of the escarpment, is a small oval dome of pink gneiss. Towards the 

 north end of the dome four shafts, on a line transverse to the longer axis, 

 penetrate the overlying limestone and show that the dip is nine degrees 

 east on one side, and very much less on the other. A short distance away 

 from the dome the strata have a dip of less than one degree. Near the 

 southern end, where the gneiss is exposed, the limestone strata, quite 

 close to the contact (the last (ew feet are covered with sod) are in an 

 attitude which indicates that they abut against the gneiss. The higher 

 strata, which once must have overarched the dome, have been eroded 

 away. Here then we have beds of limestone strictly conformable with 

 each other, and parallel to the surface upon which they rest, where seen 

 in the shafts, arching over a dome of gneiss. So far as could be 

 ascertained there is no evidence of post-sedimentary elevation. 



In the valley of Mill creek, a small stream, the outlet of Sydenham 

 lake, about five miles from the main area of the archean, is a small ridge 

 of gray micaceous gneiss. The valley of the creek is about one mile in 

 width, and flat floored ; the nearest of the two bounding escarpments is 

 400 yards away, and the crest is 105 feet above the valley floor. The 

 small crystalline ridge has evidently been exposed by the agency which 

 carved the deep broad valley. Similar exposures of gneiss are found in 

 the depressions occupied by many of the lakes of the Trent river system, 

 on the Moira river, and elsewhere in like situations. 



Still further east, at Kingston Mills, just west of the bridge across 

 the gorge of the Great Cataraqui creek, there is a railway cut transverse 

 to a granite ridge. The west end of this cutting passes through a small 

 mass of calcareous quartz conglomerate, lying in a hollow upon the 

 flank of the granite. The contact between granite and conglomerate 

 shows in cross section on both sides of the cutting. There are, in all, 



