1 900-1.] 



Physical Geology of Central Ontario. 



149 



from the central core. On the northeast side the dip is five and a-half 

 degrees to the south of east, but away from the core, this also diminishes. 

 The limestone is compact, fine-grained, and fossiliferous. In texture it 

 much resembles that found upon the higher exposures on the southwest 

 flank of the granite ridge at Kingston Mills, (figure 3.) 



Figure 3. — Transverse section of the quaquaversal dome at Fort Hill, Kingston. Horizontal and verti" 

 cal scales equal. 



One-third of a mile east of the dome, the nearly horizontal lime- 

 stones form an easterly-facing escarpment, talus covered, facing a large 

 area of crystallines, partly gneiss, but mainly a dark red granite. The 

 valley between is about one hundred yards in width, but towards the 

 northeast the depth and width diminish, and the limestones, still almost 

 horizontal, outcrop near the granite (figure 4). This granite is itself a 



-r^ f ^^"-''^•^?^-|^> T^fy 



50 feel. 



Figure 4. — Diagram to show the apparent relative positions of the limestone and crystallines east of 

 Fort Hill. Horizontal and vertical scales equal. 



large inlier from the western side of the arm of the crystalline series 

 which connects the Canadian archean with that in New York. East 

 and north, through the township of Pittsburg, there are many ridges 

 of gneiss with a general northeast trend, thes trikes being sympathetic 

 with the direction of the ridges, and the dips nearly vertical, or when 

 inclined, the inclination is generally the same on both sides of the 

 ridge in question. Between some of the ridges long tongues of 

 horizontal strata extend northeastward, frequently, though not always, 

 with an escarpment facing the gneiss. In no place does the limestone 

 show a dip sympathetic to the inclination of the ridge adjacent, 

 though there are cases where the relative positions of the two are such 

 that the dip ought to be nearly thirty degrees, if the gneissic ridge were 

 elevated after the deposition of the sediments. 



With reference to these ridges of gneiss, and to the unroofed dome 

 at Fort Hill, Dr. Drummond writes : " The Laurentian strata have been 

 here elevated into these great ridges at a period subsequent to the 



