126 J\'o Coal in the JYew York Rocks. [Sept., 



Notwithstanding, however, that the above inferences are ad- 

 mitted by most persons who have examined the subject, there are 

 many still, who are unwilling to be convinced that coal is not a 

 product of the rock of New York, or of the Silurian system. 

 Those persons are stumbled by the fact, that coal is found in 

 Rhode Island and Massachusetts, in a formation which rests upon 

 the primary, or the Taconic system, which is older than the Silu- 

 rian. This seems to be, at least on the first impression, a fact 

 which must overthrow what has been asserted in regard to the 

 absence of coal in the New York rocks; for if rocks which rest 

 immediatel}^ upon the primary contain coal, may not the still 

 newer ones of the New York system contain coal also. At least 

 it would appear that there is nothing incompatible with the ex- 

 pectations of coal, provided it is found in rocks as old as those of 

 Rhode Island and Massachusetts. But notwithstanding the plau- 

 sibility of this view, it is nevertheless erroneous; for, though the 

 coal rocks of Rhode Island may rest upon the primary, stilf it by 

 no means proves that they immediately succeed the primary. 



It is not true as some suppose, that there is an uninterrupted 

 succession of strata. The iact is, that many interruptions have 

 occurred in the deposition of rocks. Those interiuptions have 

 been occasioned by the oscillations of the earth's surface. Only 

 a part of the earth's surface is, or ever has been submerged at 

 one time. Nodeposites take place except during a submergence. 

 Hence a given section of country may be dry land during 

 several geological epochs, and when a new submergence actually 

 occurs, the character of the deposits which will then take place, 

 will be those which are peculiar to, and belong to the era. 



Thus it was with Rhode Island, for a long period, even during 

 the whole of the Silurian, when the New York rocks were being 

 deposited, it was entirely above water, or dryland; but at the 

 era of the coal deposites, it was submerged; and hence the depos- 

 ites themselves partook of the character of those which were in 

 progress in Pennsylvania, Ohio, England and Wales. The or- 

 ganic beings are identical with those found in the deposites re- 

 spectively, although they are widely separated from each other. 

 We are then to determine first of all, the age of a formation, and 

 we cannot determine this from the age of the inferior rocks, nei- 

 ther can we by the lithological characters or mineral contents; at 

 least these may all be fallacious. When we see however, that 

 the plants of the small coal basin of Rhode Island, are identical 

 with those of the coal formation of Pennsylvania, and other coal 

 bearing regions, we may then safely conclude that the formation 

 itself is of the same period notwithstanding it rests on the oldest 

 rocks of the globe. 



This leads us to say that the indications of coal are those which 



