OF THE NEW-YORK SYSTEM. 115 



1. The Champlain division, embracing as members, 



1. Potsdam sandstone. 



2. Calciferous sandstone. 



3. Chazy limestone. 



4. Birdseye limestone. 



5. Isle-Lamotte marble, 



6. Trenton limestone. 



7. Utica slate. 



8. Lorainc shales, terminating in a gray sandstone, and sometimes a conglomerate which has 



been called Oneida conglomerate, and sometimes the Shawangunk grit. 

 These masses constitute the base of the New- York system ; and though w'c may not regard 

 the subsequent division with the same favor, this, to say the least, embraces a series of 

 rocks, which, in natural history, would be considered as a natural series ; or rather they 

 may be looked upon as having been formed during a period,* in which the condition of the 

 earth, as it regards heat and cold, and other circumstances which modify life, were quite 

 uniform for the entire period thej' were being deposited. They might even constitute a 

 system independent of the subsequent formations. 



2. The Ontario division ; the individual rocks of which are, 



1. Medina sandstone. 



2. Green shales, embracing one or two thin beds of oolitic iron ore; grits, coarse and fine, in alter- 



nating layers with the shales, some of which answer for flagging stone. 



3. Thin beds of limestone filled with the Pentamerus oblongus. 



4. Niagara limestone. 



5. Red shale. 



6. Green calcareous shale, with a bed of limestone with cavities in the form of hoppers. 



* PERIODS. 



What characterizes a geological period .' If the reader casts his eye for a moment over the pages of history, what 

 will he find ? Something quite analogous to what is termed a period in geology. Talce for example European history 

 from the dark ages down to the present, will he not find certain events crowded into a distinct interval, which will 

 characterize it from all others, and set it forth prominently to the gaze of tlie world ? The period termed the Reforma- 

 tion is clearly such an one as will illustrate our meaning. But though distinct and prominent, it was not a sudden 

 movement : it did not break out at once like a meteor, which comes forth from darkness and lights up tlic sky for a 

 moment, and then as suddenly disappears — a something for which the world was wholly unprepared. Vet it had a 

 beginning and an end. The historical period, if we scrutinize it, has its %vay prepared, and events are long shaping 

 themselves that way ; and when it actually commences, though it begins by some striking event, still that event is 

 but one effect of what has already transpired : the world is prepared for it. As the burning of the papal bull by 

 Luther in 1540, was, in one sense, the beginning of a period ; yet was it foreshadowed by the past, and what had 

 transpired rendered it, if we may use the expression, possible. So the geological periods never appear to have com- 

 menced by a sudden physical change in the condition of air, ocean or earth ; nor in tlie great domain of life, either by 

 a great and wide-spread destruction, or by a remarkable creation of wonderful forms. Still, when periods are com- 

 pared, when the vestiges of one period are brought by the side of another, they are quite unlike, and yet are befitting 

 the state and condition in which tliey appear; and as men are the actors in all historical periods, so nothing in the 

 geological period appears but what might be expected from the agents then already in operation, excluding all traces 

 of beings inconsistent with nature in any time or in any circumstances. He who looks npon the past periods as more 

 remarkable than the present, takes a wrong view ; and though it is clear that times and seasons have been for other 

 beings than those of the present, yet the present is, if any thing, the most remarkable of all periods. 



15* 



