On the Transition Rocks of the Cataraqui. 91 



In following the rules laid down by the geologists we have alluded 

 to, as well as in tracing carefully the natural appearances, we must ad- 

 mit cautiously, however, that there are several distinct known species 

 of transition formations, and amongst these the most conspicuous and 

 easily recognizable are the schistose ; the felspathose, porphyries, 

 sienites and greenstones ; the granular and compact limestones, with 

 gypsum and rock, salt ; euphotides and the aggregated rocks (gray- 

 wackes and calcareous breccias.) These are variously arranged and 

 described by diflerent authors, and amongst them granite and gneiss, 

 mica slate and quartz rock are frequently enumerated. The latter 

 are, however, types as comparatively rare as the greywacke schist 

 and transition clay slate are characteristic ones. These rocks asso- 

 ciate according to some particular laws which have not been yet made 

 manifest, although there has been proof enough afforded to state, 

 that " transition clay slate '^ and black limestone, clay slate and por- 

 phyry, clay slate and greywacke, porphyry and sienite, granular 

 limestone and anlhracitous mica slate, form geognostic associations 

 in all parts of the world."! ^^^ notwithstanding the geologist is 

 fully aware of these circumstances, they are so exceedingly com- 

 plicated in their alternations, that he can with the utmost difficulty 

 satisfy himself concerning the relative ages of even a few of these 

 rocky masses, as some of those which appear by their associations 

 to be decidedly transition, in their peculiar characteristics are not 

 separable from the primitive family, whilst others are as difficult to 

 discriminate from those masses of igneous origin with which they ap- 

 pear so suitably allied. 



Many learned men, and amongst others Humboldt, have endeav- 

 ored to classify the genera of transition rocks, and to divide them 

 into groups, but there appears, at present, so much difficulty in the 

 undertaking, and so many contradictory results occur, that it becomes 

 impossible to follow them through their chains, or rather, labyrinths 

 of reasoning, although the exposition of the six great groups given 

 by the aboveraentioned geognost, in his essay on the superposition of 

 rocks, is eminently worthy of its author, and abounds in facts, which 

 will, hereafter, greatly assist towards reducing the matter to the laws 

 of truth. 



* Greywacke schist. t Humboldt on the superposition of rocks. 



