658 



CHAPTER XXV. 



THE HURONIAN AND LAUEENTIAN PERIODS. 



INTRODUCTORY REMARKS THE HURONIAN SYSTEM THE LAURENTIAN 



SYSTEM SUMMARY OF THE GEOLOGICAL HISTORY OP ACADIA 



CONCLUSION. 







The formations last described carry us far back through the loug 

 ages of the earth's geological history to the beginning of the 

 Palaeozoic period ; but still older rocks, indicating still earlier periods, 

 are known to geologists. These, until lately, were regarded as azoic, 

 or destitute of remains of life ; but the discovery of Eozoon Canadense 

 now entitles them to the name Eozoic, or those that indicate the 

 morning of that great creative day in which the lower forms of animal 

 life were introduced upon our planet. Formations of this age occupy 

 great breadths in the northern part of the North American continent. 

 All that rocky and hilly region on the north side of the St Lawrence 

 Gulf and River, constituting the Laurentide Hills, reaching from 

 Labrador to Lake Superior, and the extension of it to the south in 

 the Adirondac Mountains of New York, consists of Laurentian rocks, 

 and these are skirted on the south, more particularly on the shores of 

 Lake Huron, by the newer Huronian series, which, however, like the 

 first, underlies all the Silurian formations, The rocks of both these 

 great groups, as might have been anticipated from their vast anticmity, 

 and the vicissitudes which the earth has undergone since their for- 

 mation, are in a highly metamorphic state. Still there is good evi- 

 dence that, like the altered Silurian rocks above described, they were 

 originally sedimentary deposits, formed in the sea, and subsequently 

 brought into their present state. 



Until a few years ago, we had no evidence of the existence of these 

 old formations in Acadia, or indeed elsewhere on the Atlantic coast 

 south of the Gulf of St Lawrence, other than the vague suspicion that 

 some of the metamorphic rocks of unknown age might possibly be 

 referred to these periods. The discovery of the Primordial fossils 





