284 



HIGHGATE SPRINGS. 



Fia. 180. 



Segregated veins, Highgate. 



The variation in the dip and strike at Highgate Springs and vicinity is so great, and so many observa- 

 tions were recorded, that we give a sketch of these irregularities from the note book of the Principal of the 

 Survey. The figure includes a space 200 by 175 rods, and though the strikes have not all been laid down 

 with strict accuracy, their general position is correct. One of the most remarkable things to be noticed is 

 the great curve in the strata, from C to E, and the accompanying anticlinal from A to C, the distance is 

 20 rods; from C to the break in the strata, 93 rods. The width of this gap is 11 rods. The length of the 

 remainder to D, is 55 rods. Thus the length of the curve from C to D is 159 rods; and from C to E, the 

 distance is over 200 rods. Where the bend is greatest, the strata are much broken, and the fractures are 



mostly filled with veins of calcite. Fig. 180 shows these veins of calcite crossing 

 alternate strata of limestone, upon the west side of the curve. The short 

 lines a, a, represent the veins in the strata, S, S. 



Inside of the curve there are a few ledges; all of which are represented upon 

 this sketch. At the point of land jutting out into the Missisquoi Bay, the strata 

 are beautifully plicated. South of the road to the Harbor there are two ledges 

 dipping in opposits directions, which are largely composed of a slaty rock, con- 

 taining only a small per cent, of lime. Another curve can be traced around the inner one; but the dip 

 varies upon the west side from the inclination of the inner one. The dip of the ridge upon the east does 

 not vary much from that of the inner curve; but if it be followed round, it will be noticed that the dip 

 of the outer curve at the southwest corner of the figure is twenty degrees greater than that of the inner 

 one in fact it is almost perpendicular. The same ledges, continued, dip at a very high angle to the east. 

 We suppose that the normal dip of this ridge is to the west, but the lateral pressure from the east, which 

 folded the strata, was so strong that it pushed the whole fold to the west, and thereby brought the west 

 part of the west side of the anticlinal under the east part of the same. And as a force always acts with the 

 greatest intensity at right angles to its direction, therefore the strata upon the south side of the curve have 

 more of the normal dip than those upon the west side. 



The rudiments of a third and fourth curve appear upon the figure. It would be difficult to trace them 

 out as fully as the inner ones, because the ledges are mostly covered up south of what is represented in the 

 figure. The next southern ledge of Trenton limestone that we have seen, is at Mr. O'Neil's Chouse, less 

 than two miles south of the Franklin House. These curves seem to indicate the southern extremity of the 

 Trenton limestone. This range increases in width as it passes into Canada, being the widest at Philips- 

 burgh, at the head of Missisquoi Bay. It extends to Deschaillons upon the St. Lawrence, below Montreal. 

 It lies between ranges of the Hudson Eiver Group, according to the Canada survey, and is the basis of the 

 great anticlinal dividing the Palaeozoic rocks of Canada into two basins, the eastern and the western, as 

 denominated by Sir W. E. Logan; the one extending to the western United States, and the other to the 

 Atlantic Ocean. 



Fio. 181. 



Section in Trenton Limestone at Higligate Springs. 



Fig. 181 represents a section crossing the ridges delineated in Fig. 179. The character of the limestone 

 is given to the principal varieties in the sketch. West of the ledges there is a vast swamp, extending over 

 the east part of Hog Island. It is upon this swamp that we should expect to find the calcareous slates 

 above the Trenton ; but their easily decomposed nature has worn them away, as it has done upon the east 

 side also. 



