46 BULLETIN OF THE NATURAL HfSTORY SOCIETY. 



miles, from Beaver harbor to Xortoii, where it is covered 

 by later deposits, it is only four or five miles wide; and 

 it is bounded by nearly straight lines throughout. This 

 tells us that there were profound faults or breaks in the 

 earth's crust along eacb side of this range, witli jirobably 

 a sinking area between, into which and on which the 

 lava streams were poured. These faults were the initial 

 lines of valleys which continue to exist to the present 

 day. 



A glance at the condition of these valleys, as they 

 were developed during the passage of the ages, may be 

 of interest. But we can only refer to a few of the more 

 important epochs, taking up first their aspect at the close 

 of the Cambrian time. 



The Iluronian epoch, previously referred to, was 

 marked by the existence of animals of low organization 

 — the Protozoans; now an advance liad occurred, and 

 we find the seas were tenanted by Crustaceans and 

 Molluscs of various kinds, as well as many soft animals 

 which have left tracks on the surface of layers of sand 

 and mud of which the rocks are made up. The volcanic 

 fires had died out, the sea Lad covered the land in the 

 region of which we speak, except, perhaps, a few project- 

 ing hills ; and over the lava beds, sunk beneath the 

 ocean, was spread layer after layer of sand and mud, 

 charged with the cast oft' tests of trilobites, the shells of 

 molluscs, and the rod or net structures of hydroids. 



The 8aint John Fault. 



The muds in which these were buried accumulated 

 to a thickness of four thousand feet, and subsequentl}^ 

 were crowded and folded together by a resistless pressure 

 from the south, until the whole series was at one point 



