450 R. T. Hill — The alleged Jurassic of Texas. 



occurrences, from two to live feet thick at one place and less 

 than fifty at the other, represents an outlying isolated, attenu- 

 ated outcrop of the great body of Lower Cretaceous which has 

 a development, of over 2,000 feet in Texas, and from which 

 they have been disconnected by prehistoric and recent denuda- 

 tion, and to which I have devoted thousands of miles of travel 

 and careful study and field work during my lifetime. 



At the first of these localities he collected from a "lime- 

 stone five feet thick,"* one species of Ostreid (" Gryphcea 

 jntcheri") and at the second from a bed given by him as 30 

 feet thick, two other species of the fossil Ostreidse (called by 

 him G. dilatata and O. marshii). These species, with two or 

 three hundred molluscan forms, since reported by others, are 

 now known to constitute the faunas of the Lower Cretaceous 

 formations of Kansas, New Mexico, and Texas. 



Upon the supposed resemblance of the fossil oyster from the 

 first mentioned of these localities to certain forms in the Cre- 

 taceous of Switzerland, and the fact that it occurred as a shell 

 agglomerate or "lumachelle" resembling in its lithologic 

 facies similar "lumachelle" of Switzerland, he referred the 

 beds containing it to the " Neocomian " epoch, and has since 

 used this determination as a basis of his subsequent discussion 

 of this system, as other workers discovered and delineated the 

 great series of strata and its areal extent to which this single 

 outcrop has proved to belong. Likewise on the supposed resem- 

 blance of the two fossil oysters from Pyramid Mount in New 

 Mexico to forms from the "Oxfordian" and "Lower Oolite 

 groups "f of England and France, he referred these beds to 

 the Jurassic period- — an opinion which he has since rigidly 

 maintained and used as the basis for asserting the Jurassic age 

 of various other and entirely distinct strata since discovered 

 and described by later writers throughout the Texas region, 

 and coloring vast areas of what we now know to be Lower 

 Cretaceous and Tertiary, upon maps which he has compiled.^ 



By his own statement, Professor Marcou has spent not over 

 five hours of his life-time in observation of the formations 

 under controversy. In fact he has never seen the main body 

 of the Cretaceous in Texas or Indian Territory at all, and has 

 never visited the localities, nor examined the vast collections 

 subsequently reported. " I have explored only a very small part 

 of Texas/' he says, " only a simple road in the Panhandle,"§ and 

 1 might add, that his road lay entirely through the Permian of 



* U. S. Pacific Railroad Explorations, 1853-54, vol. iv, p. 43, H. Doc. 129, 

 Washington, 1855. 



f Geology of North America, Zurich, 1858, p. 19, and in several other publica- 

 tions. 



i '' Geology of North America," Geological Map of the World, etc. 



§This Journal, September, 1897, p. 208. 



