148 



SCIENCE. 



FN. S. Vol. YIII. No. 188. 



brought out in my paper, but in an imper- 

 sonal manner that I hoped would offend 

 none of the craft. 



The prompt and vigorous rejoinders that 

 even my first informal announcement drew 

 from two paleobotanists, A. Hollick and L. 

 F. Ward,* showed that I had trespassed 

 upon their bailiwick, and that some of the 

 questions raised they had settled to their 

 own satisfaction. As their ideas in regard 

 to the value of fragmentary fossil plants as 

 evidence of geologic age differed so widely 

 from my own and from those of many pale- 

 ontologists, no specific reply on my part 

 seemed necessary, and I have none to make 

 now. Professor Ward has admitted that 

 the plants found with the vertebrates in the 

 Potomac beds of Maryland maj^ be Jurassic, 

 and that removes one of the main points at 

 issue between us. His words are as fol- 

 lows : 



"If the stratigraphical relations and the 

 animal remains shall finally require its 

 reference to the Jurassic the plants do not 

 present any serious obstacle to such refer- 

 ence." (Loc. cit., p. 759.) 



That the more eastern beds may repre- 

 sent a somewhat higher horizon I can 

 readily believe, but I must doubt the evi- 

 dence that would separate so characteristic 

 and homogeneous a series of sands and 

 plastic clays into two sections, one Creta- 

 ceous and the other Jurassic. The few im- 

 perfect plant remains that we are told au- 

 thorize this separation must be reinforced 

 by other testimony to obtain even the sup- 

 port of probability, especially when paleo- 

 botanists differ so widely among themselves 

 as to the real significance of the fragmen- 

 tary remains they describe. 



Next in order among my reviewers was 

 E.. T. Hill,f well known for his researches 

 in the geology of Texas, but apparently not 

 familiar with the typical Jurassic, East or 



* Science, Vol. IV., p. 571 and 757, 1896. 

 t Science, Vol. IV., p. 918, 1896. 



West. He evidently had not read my 

 paper carefully, though he criticises it at 

 length, mainly to confirm his own conclu- 

 sions as to the Cretaceous age of certain 

 deposits in Texas, which he seems to imag- 

 ine I do not endorse. As I especially 

 avoided expressing any opinion on that 

 point, or in regard to the Dakota being the 

 base of the Cretaceous in this country, as I 

 have already stated, no reply at present 

 seems called for on my part, although I 

 hope later to refer to the question he raises 

 about the age of the so-called southern Po- 

 tomac. 



I took it for granted, in my paper cited, 

 that American geologists who were not fa- 

 miliar personally with the great develop- 

 ment of the Jurassic formation in Europe, 

 or who had no opportunity of examining 

 typical sections of this formation in west- 

 ern America, or of seeing its deposits in 

 place full of characteristic fossils and ex- 

 tending hundreds of miles in half a dozen 

 States, were at least sufBciently acquainted 

 with the literature of the last twenty years 

 to know that two of the best-marked Juras- 

 sic horizons in any part of the world existed 

 in this countiy. 



Although my communication, as printed, 

 was in fairly clear English, I find it was 

 misunderstood in various other points, as 

 subsequent reviews soon showed. If these 

 marks of disapproval had been recorded by 

 fireside geologists, who so often differ with 

 those who furnish facts, I should have fol- 

 lowed my usual rule and made no reply. 

 They were, however, mainly written by 

 field geologists who had seen something of 

 the West, and ought evidently to have seen 

 more, for the facts I stated can be readily 

 verified at any of the localities mentioned 

 and at many others. The failure to do so 

 well illustrates a law of human nature, 

 namely, that men see what they have eyes 

 to see. The West is an extensive country. 

 The plant men who go there seem to see 



