86 On the Transitioti Rocks of the Cataraqui. 



It is well known that transition granites are found superincumbent 

 upon beds of talcose limestone, and that masses or nodules of lime- 

 stone, as well as of other rocks, have been observed imbedded in 

 such substances, but I do not remember ever to have heard that 

 granite covered by, or in connection with, transition limestone, inter- 

 mingled and interlaced itself and its constituent particles, with that 

 formation.* 



Along the north eastern edge of the great basin of North America, 

 the ridge of granites which marks the division between the primary, or 

 the transition, and the secondary countries, is denuded to a consider- 

 able extent, until it approaches the St. Lawrence and crosses that 

 river by the vast chain of amphibolic rocks which divide the beautiful, 

 the extraordinary, and the innumerable channels in which that great 

 stream is forced to wind its way, amidst the lovely scenery of the 

 Thousand Islands. 



Kingston, or Cataraqui, at the outlet of Lake Ontario, is the 

 point where, to the eye of a casual observer, this granitic ridge seems 

 to terminate its course ; for at this point, the western extremity of the 

 Thousand Isles, the ridge is almost lost, and the character of the 

 rock itself appears wholly changed, as it intermingled with syenites 

 and serpentinite at Cedar Island, or becomes wholly syenitic, as at 

 the northern extremity of Hamilton cove, or resolves itself altogether 

 into a singularly hard compound, intimately mixed in minute grains 

 of felspar', quartz and carbonate of lime, with hornblende and mica- 

 ceous iron at Point Henry. 



Numerous varieties of syenite exist, in a very limited space, on 

 Cedar Island, and appear to pass into each other, by rapid alterna- 

 tions, in a small compass, whilst the specimens of serpentinite aggre- 

 gate with them, and but for the little carbonate of lime they contain, 

 would appear, in many instances, more like real greenstone than 

 euphotide.f 



The granitic associations are again lost and vast tables of transition 

 limestone, with few or scarcely any organic remains, entirely cover 

 them, for the space of above four miles to the north east of Point 

 Henry, when the granite, a kind of very hard, dark whinstone, again 



* In the Pyrenees, vertical beds of granular primitive limestone, intermix with 

 granite and trap. 



t Besides this serpentinite, there are also specimens in which fibrous lamellar 

 treraolite, epidote and felspar, assume the exact appearance of verde antico. 



