LETTER TO THE SECRETARY. XXVII 



of tlie earth, even if the others are not there present for study in direct 

 connection. In no other way can the relative geological age of forma- 

 tions be accurately known. Therefore, admitting the utility of geology 

 at all, the practical utility of paleontology must be plainly recognized. 



But it is not only in this general way that the practical utility of 

 paleontology is shown, for there are many ways in which its application 

 gains or saves from useless expenditure great sums of money. 



The study of fossil remains found in the strata which are associated 

 with beds of coal, and those found in the formations which respectively 

 underlie and overlie the coal formation, show that each is so character- 

 ized by its own peculiar fossils that they can be unhesitatingly recog- 

 nized by them, even when no coal is visible, and the lithological charac- 

 ter of the strata is found to be different from what it was where last 

 observed. Thus, if, in the geological examination of a district, the rocks 

 at any certain place are found to contain the fossils peculiar to the for- 

 mation which belongs above that which contains the coal, the latter lies 

 beneath, and coal may reasonably be sought by deep mining. If, on the 

 contrary, the formation examined be found to contain the fossils pecu- 

 liar to the one whose place in the geological scale is beneath the coal 

 formation, search for coal in the whole region in which that formation 

 is at the surface is sure to result in failure, because the coal formation 

 has either been removed by erosion, or it was never deposited there. 

 In either case it is a certain waste of money to search for coal under 

 such circumstances. 



The history of mining has been said to be a history of failures ; and 

 this is doubtless true as regards preliminary operations or prospecting. 

 It is especially true as regards prospecting for coal, and it is safe to say 

 that far the larger part these failures might have been avoided by a 

 moderate amount of paleontological knowledge and an observance of its 

 teachings. 



The sums which have been expended by private enterprise in the 

 search for coal in the different States of the Union, in places where one 

 possessing the merest rudiments of paleontological knowledge would 

 have known better, is enormous ; and this waste of labor and capital can 

 be stopped only by a proper diffusion of the knowledge referred to. 



Besides the determination of these facts of immediate practical use in 

 limited districts, the paleontological study of the formations enables us 

 to map large regions and to indicate the boundaries within which it is 

 reasonable to search for coal or other valuable products, and beyond 

 which such search is sure to result in failure. Many examples of this 

 kind might be cited, but these remarks will be closed with a single illus- 

 tration drawn from the recorded results of this survey. Coal is found 

 abundantly in the Laramie formation at the eastern base of the Rocky 

 Mountains in Colorado. The associated strata are found to be charac- 

 terized by peculiar fossils. The different formations which immediately 

 underlie the surface of the great plains east of those mountains are so 



