ONWARD THROUGH THE AGES. 129 



the diligence and learning of Dr. J. W. Dawson, of M'Gill 

 College, Montreal. How sparse and desolate must have 

 been those forests ! No voice of animated nature was yet 

 heard among those scattered pigmy trees. They are ar- 

 borescent ferns and lycopodiums — a new idea incorporated 

 in vegetal existence — but how prophetic of that which is 

 to come ! Nature always issues her bulletins. We stand 

 now in an age of the world which antedates the advent of 

 all our familiar forms, and read the announcement of the 

 coming riches of the Carboniferous era. A stranded log 

 of drift-wood becomes eloquent in the utterance of pro- 

 phetic truth. 



Another age passed which the scientific world hesitates 

 to attach to the future or the past. Is it Devonian or Car- 

 boniferous ? Throughout the West the sediments of this 

 age gave rise to a noticeable formation which has been 

 styled the Marshall group, because the characteristic rocks 

 and fossils of the period may be studied at Marshall, in 

 Michigan. This is the rock so extensively worked in the 

 vicinity of Cleveland, and at Waverly, Ohio. It furnish- 

 es the excellent grindstones of Berea, and those known as 

 Huron grindstones in Michigan. It is the greenish or red- 

 dish-yellow sandstone occurring in Southern Michigan, and 

 trending northward into the bight of the coast which sep- 

 arates Saginaw Bay from Lake Huron. It underlies the 

 limestone bluff at Burlington, in Iowa, and makes itself 

 known at numerous localities throughout the northwestern 

 states. In New York, it is perhaps the formation corre- 

 sponding to this which caps the Catskill Mountains, and 

 has hence been styled the Catskill group. It covers a large 

 area in Northeastern Pennsylvania. In this formation, 

 throughout its wide extent, are found the scales and teeth 

 of fishes, which recall the relics studied by Hugh Miller in 

 the quarries of Cromarty, and hence we have been inclined 



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