On the Transition Rocks of the Cataraqui. 



243 



ing changed the form or nature of the rock, by hardening, baking, 

 or calcining it, and without even altering its usual dark color and as- 

 pect, but is detached into it, in large and small nodules or masses, 

 conjoining with it at the lines of contact of the two rocks, and shoot- 

 ing crystals of quartz and hornblende into the lime, in such a man- 

 ner as would naturally occur, if the substance of the sienite and of 

 the limestone were both in a soft or jelly-like state originally, and 

 gradually hardened together. 



Every variety of appearance is thus assumed which the sienite 

 and limestone could afford, but the limestone has yielded few or 

 none of the prominent features of its original character. On exam- 

 ining a vast number of fragments, taken from the places where these 

 rocks were in contact, I was surprised in polishing some of them, in 

 order to exhibit their singular appearance better, to find fossils at 

 the point of junction. 



The best defined of these I have selected, and the accompanying 

 is a drawing from one of them. 



A mass of shells. 



This is about half the real size of the specimen, taken from the 

 southwest end of Cedar Island ; the little round spots on the lime- 

 stone side denote the quartz, as well as the long curved lines, whiter 

 than the other portions, which have shot into the calcareous body from 

 the sienite ; the whitish undefined band, between the sienite and the 



