THE RELATIONS OF PALEOBOTANY TO GEOLOGY.^ 



By Dr. F. H. Knowlton, 

 United States Geological Survey. 



Although there is vague mention of fossil plants in literature as 

 early as the thirteenth century, and unscientific adumbrations in 

 the faintly growang twilight of the succeeding centuries, the real 

 science of paleobotany did not have its beginninf' until well on in 

 the nineteenth century. With the publication, in 1828, of Brongni- 

 art's "Histoire desvegetaux fossiles" and the "Prodrome," there was 

 given to paleobotany ''that powerful impetus which found its imme- 

 diate recognition and called into its service a large corps of colaborers 

 with Brongniart, rapidly multiplying its literature and increasing the 

 amount of material for its further study" (Ward). In the succeeding 

 decades, even to the close of the century, the students of paleobotany 

 were mainly occupied in accumulating data as regards distribution, 

 both areal and vertical, and the opening decades of the present cen- 

 tury find the subject a recognized, respected, coequal part of the 

 general field of paleontologj^. 



Paleobotany, together with all the other branches of paleontology, 

 admits of subdivision into two lines or fields of study — the biological 

 and the geological — depending upon the prominence given to the one 

 or the other of these phases of the subject. The biological study is, 

 of course, concerned especially with the evolution of the vegetable 

 kingdom, that is, with the tracing of the lines of descent through 

 which the living flora has been developed. As tliis side of the ques- 

 tion will be taken up by other contributors to this discussion, it may 

 be dismissed from further consideration, as the geological aspect is 

 almost exclusively the phase of tlie subject to whicli the present 

 paper is devoted. 



In the first place it w\\\ be necessary to call attention to the fact 

 that the successful use of fossils of any Idnd as stratigraphic marks 

 is — or at least may be — entirely independent of their correct bio- 

 logical interpretation. To most botanists, and indeed to some paleo- 

 botanists, this statement will doubtless come as a surprise, since 

 they have come to imagine that the impressions of plants, the form 



1 Reprinted by permission from The American Naturalist, vol. 4G, April, 1912. 



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