INTRODUCTION. 91 



limestone lies to the west of the mountain range, while the transported sediments 

 diminish in the same direction. 



We have in this view an explanation of the condition which Sir Charles Lyell 

 says " seems to be the result of some general cause." No cause could be more 

 general than the one which I maintain, and none more completely iu harmony 

 with the simplest elementary principles of geology, and in accordance with all 

 the laws, physical, chemical and vital, attendant upon the distribution and ao- 

 cumulation of geological formations. 



The same explanations, to a great extent, apply to the absence of organic re- 

 mains. For though we do know that the process of metamorphism obliterates these 

 bodies partially or entirely, still, during the rapid deposition of sediments, few 

 animals could have lived ; and when we take into account not only the rapid 

 accumulation, but the unfitness of the materials for the support of animal life, we 

 can not be surprised at the paucity or absence of its evidences. 



It is not necessary to go into metamorphic strata for examples of this kind. In 

 the Potsdam sandstone, the oldest known fossiliferous rock, we have evidences in 

 some places of very rapid accumulation ; and in such cases, fossils are extremely 

 rare, or do not exist at all. In the Catskill mountains, where accumulation was 

 evidently rapid, there are few fossil remains, though the beds are nearly horizon- 

 tal, and not metamorphic beyond the evidence of certain infl^^flences before noticed. 

 Other examples might be named, which do not come within the classification of 

 red rocks or red sandstones and shales, which are notoriously destitute of fossils. 



Not only is this true, but in this mountain accumulation of more than three 

 thousand feet, which can be examined throughout, there are no calcareous beds 

 worthy of consideration. And the same is true in regard to the thousands of feet 

 of sedimentary strata froto the Hamilton group to the Coal measures, which, in 

 Southern New- York and Northern Pennsylvania, are almost destitute of calcareous 

 matter, with the exception of a few concretions, or thin bands of limited extent, 

 produced by the aggregation of fossil shells. We are forced to admit, therefore, 

 that this absence of calcareous matter is dependent on the original character of 

 the sediments; for metamorphic limestones, if once existing, are as unaffected by 

 the ordinary agents as limestones in other conditions. 



On the other hand, we have evidence, from the surveys of Sir William Logan 

 in Canada, that extensive bands of limestone mark a certain horizon in the Lau- 

 rentians, the oldest known metamorphic rocks ; and that these calcareous belts 

 can be traced for many miles continuously, and over a wide extent of country. 



