244 On the Transition Rocks of the Cataraqui. 



lime, seems also, from its great hardness and the difficulty of pol- 

 ishing it down to a level with the feldspar and lime, to be very- 

 pure quartz. Here and there, a small hornblende crystal may be 

 observed in the lime. The feldspar of the sienite is of nearly a 

 deep flesh color, and the lime and sienite are so closely connected 

 that they cannot be separated. The limestone, at this locality, 

 has the same appearance as the rock on the main land, and contains 

 terebratulse, two of which shells may be observed in the drawing, 

 at the very junction of the two rocks and almost in the sienite, and 

 there are traces of very large ones visible. On close inspection 

 of cut and polished specimens, the limestone, instead of looking 

 like a conglomerate, which it otherwise resembles, from the weath- 

 ering of the calcareous matter in the rock, proves to be porphyritic, 



the chief character of which is that of quartz nodules, pasted as it 

 w r ere in lime, the larger spots of sienite interspersed being only occa- 

 sional, and probably the nuclei whence the quartzose particles emi- 

 grated. It is only in the immediate neighborhood of the conjunction 

 of the limestone and sienite, that this porphyroid structure is, how- 

 ever visible ; the limestone soon regains its independence, and ex- ' 

 hibits only its usual features of dark blue stone, with occasional glim- 

 merings of crystalline lime and few organic remains. 



In its neighborhood are observed the detached tables of a grayer 

 and highly crystalline limestone, with abundance of those specimens 

 of orthocerae which have received the name of Huronia, and which 

 look so very like vertebrae as to be called back-bones by the unini- 

 tiated. On these tables are stuck, as it were, fragments of sienite 

 and of quartz, which project considerably, and have no doubt been 

 subject to the action of water, since their original contact with the 

 limestone, which has been uniformly worn away, so as to discover 

 the orthoceratites imbedded, and have been thus preserved from far- 

 ther harm by the surrounding protuberances of the harder material. 



I am well aware that the mass of impressions of marine shells, 

 nearly in and actually touching the sienite, may not be considered a 

 very strong argument in favor of the aqueous origin of that sienite, 

 as instances are said to have occurred wherein such casts of fossil 

 animal remains have remained perfect in a high state of igneous ac- 

 tion ; but yet I think it will scarcely be asserted, that at the point of 

 contact and actual junction, between a highly crystalline substance 

 in a state of fusion, and a subcrystalline and very calcinable one, in 

 a soft state also, that perfect casts of fossils would remain unobliter- 



