THE GEOLOGIST 



NOVEMBER, 1859. 



THE COMMON FOSSILS OF THE BRITISH ROCKS, 

 By S. J. Mackie, F.G.S., F.S.A. 



(Continued from page 388.) 



Chap. 6. — First Traces of the Succession of Life. — The Lower Silurian 



Rocks. 



As ONE carried beyond his depth for the first time into the waters 

 of ocean, and struggling shorewards, touches but now and then the 

 yellow sands, with every heaving wave again to be set afloat, feels a 

 delight when he plants his foot solidly on the sands, and wades 

 through shallower water to the shore, so do we after our almost 

 footless path through the wide waste of water of the first age, hail 

 with dehght our firmer footing on the spreading shores of this next 

 great geological period. 



The first argument of the antiquity of the globe is drawn from the 

 successive accumulations of strata inclosing difierent creations of or- 

 ganic beings, which form the stratified portion of the earth's crust. 



The next argument of length of time is taken from the evidence 

 which the remains of those ancient organic beings afford of the 

 long periods of their existence on the face of our earth. It is not 

 the strange obscure forms of three-lobed legless crustaceans, revealed 

 to us by such distorted and crumpled fragments that the eye is 

 strained in the effort to make out the details of their shapes, that 

 astonishes us so much as the familiar look of the little shell-fish we 

 meet in these old Silurian rocks, 



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