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On the Transition Hacks of the Cataraqui 01 



In following the rules laid down by the geologi.sts we have alluded 

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

 mit cautiously, however, thai there are several distinct known sj^ecies 

 of transition formations, and amongst these tlie most conspicuous and 

 easily recognizable are the schistose ; the felspathose, porphyries, 

 sienites and greenstones ; the granular and compact limestones, will 

 gypsum and rock saltj euphotides and the aggregated rocks (gray- 

 wackes and calcareous breccias.) These are variously arranged and 

 described by different 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 tliere has been proof enough afforded to slate, 

 that " transition clay slate* and black limestone, clay slate and por- 

 phyry, clay slate and greywacke, porphyry and sienlte, gra\iular 



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limestone and anthraeitous mica slate, form geognostic associations 



in all parts of the world."f But notwithstanding the geologist is 

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

 plicated in tlieir 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 dieir associations 

 to be decidedly transition, in their peculiar characteristics are not 

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

 discriminate from tliose masses of igneous origin witli which they ap- 

 pear so suitably allied. 



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

 ored to classify tlie genera of transition rocks, and to divide thera 

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

 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 abovementioned geognost, in his essay on tlie superposition of 

 rocks, is eminently w^orthy of its author, and abounds in focts, which 

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

 of trutli. 



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Greywacke schbt ^ Humboldt oh the superposition of locks. 



