88 On the Transition Rocks of the Cataraqui. 



ite, as the micaceous ingredient is almost, or perhaps entirely, want- 

 ing in the transition rocks of the Cataraqui. But although there is 

 every reason to be adduced in favor of other terms, inasmuch, par- 

 ticularly, as most other mineral compounds have received distinct 

 names, yet the relative ages of the granitic rocks are still so little un- 

 derstood, that we shall, in obedience to the all powerful sway of cus- 

 tom, continue thus to style them. 



In the neighborhood of Kingston, certainly, the micaceous ingre- 

 dient of a true granite disappears in the various aggregates of which 

 the more ancient rocks consist, but still the positions assumed by 

 modern geologists concerning primary and subsequent formations 

 of granites, is strikingly exemplified in the very singular distribution 

 which nature has here made of her mineral resources. 



It is asserted that the presence of tin, magnetic iron, hornblende, 

 garnet, talc and chlorite, replacing mica, as well as a tendency to pass 

 to pegmatite, characterise the newer formations of that substance, 

 which had heretofore been considered as the oldest of all known 

 mineral matter, and that primitive euphotide,* posterior to clay slate, 

 is placed at the limit of primitive and transition formations, a com- 

 pact grayish limestone passing to fine grained, connecting the eupho- 

 tide of Scandinavia, according to Humboldt the last member of the 

 primitive family, with very ancient intermediary rocks. The same 

 indefatigable geognost candidly observes, however, that it is as diffi- 

 cult to fix the ages of euphotides as it is those of granites, and that 

 those which he saw at Guanaxuato, Cuba, and Mexico, and at the en- 

 trance of the Llanos de Venezuela, connected with syenite or black 

 limestone, appeared to him to be as decidedly transition as those of 

 the Bochetta of Genoa, stratified and imbedded in the transition clay 

 slate which alternates with black limestone. f Anthracite is also said 

 to bear the same relation to the transition as graphite does to the 

 primitive and coal to the secondary formations, whilst the frequent 

 presence of hornblende and the comparative absence of quartz, are 

 also distinguishing marks between the first and the intermediary 

 classes. According to Jameson, schorl is rarely associated with 

 hornblende, and from the testimony of Cleaveland we learn that 



* A mixture of dialiage, jade and lamellar felspar, of which serpeiitinite is a va- 

 riety, with small grains of an homogeneous aspect. 



t De Buch and Brochant consideied the euphotides of Spozzia, Prato and the 

 whole of the Siennese, as primitive, whilst Beongniart asserts that they are sec- 

 ondary, or of a very recent transition class. 



