284 On the Structure and Position of Eozoon Oanadense. 



much exceeds that vast amount. — The Lower part of the Lau- 

 rentian series is represented in Scotland by the ' ' fundamental 

 gneiss " of Sir Roderick Murchison, which forms the whole of 

 the island of Lewis, and on which, in various parts of the 

 western highlands, the Lower Cambrian and various meta- 

 morphic rocks rest unconforraably. The Upper, or Labrador 

 group, seems to be represented by the Labradorite and Hypers- 

 thene rocks of Skye ; which, though formerly supposed to be 

 unstratified, correspond so closely with those of the Labrador 

 series in Canada and New York as to leave no doubt that they 

 belong, like the latter, to a regularly stratified system. — The 

 ' c primitive gneiss " formation, again, which attains at least an 

 equal thickness in Norway, has been shown to correspond 

 with the Laurentian series of Canada ; and the " primitive slate" 

 formation which rests upon it is no less remarkably similar at 

 once to the Huronian of Canada and to the Lower Cambrian 

 of our own island. — The labours of Sir Roderick Murchison in 

 Central Europe have shown that the ancient gneissic series of 

 Bavaria and Bohemia, which underlies the " primordial zone " 

 of Barrande, with a vast thickness of intervening clay -slate, 

 corresponding to the Lower Cambrian, is the equivalent in 

 position of the Laurentians of Canada and Scotland ; and that, 

 like them, it is divisible into an older and a newer series, the 

 two together attaining the colossal thickness of 90,000 feet. 



The following Table represents the general results of the 

 inquiries whose history has been thus briefly sketched; 

 showing the present state of our probable knowledge of the 

 two vast series of stratified rocks, the Cambrian and the 

 Laurentian, which underlie the Lower Silurian : — 



GBEAT 

 BBITAIX. 



NOBTH 



AMEBICA. 



SCANDINAVIA. 



CENTEAE 

 ETJBOPE. 



Upper Cambrian. 

 Lower Cambrian. 



Hypersthene rock) 

 of Skye. j 



I Fundamental Gneiss. 



Potsdam Sandstone. 

 Huronian. 



Upper Laurentian \ 



Lower Laurentian / 



Alum-schists. 

 Primitive Slates. 



Primitive Gneiss . 



Primordial zone. 

 Primitive Slates. 



Primitive Gneiss. 



" The united thickness of these three great series" (the 

 Huronian and the Upper and Lower Laurentian), says Sir 

 William Logan, " may possibly far surpass that of all the 

 succeeding rocks, from the base of the Palseozoic series to the 



