R. T. Hill — The alleged Jurassic of Texas. 455 



Tertiary Plains drift, and derived from a geological position 

 unknown, and has been studied by Professor Ward. Even if 

 it should prove of Purbeckian age it would still be from a 

 much higher horizon than Professor Marcou's alleged "Oxford- 

 ian," " Oolitic," Jurassic of New Mexico. 



On page 198 he accuses me "of making a clean sweep of 

 the marine American Jura," and quotes a paragraph from me 

 in which I stated that " there are reasons for suspecting that 

 no marine Jurassic formations of Atlantic sedimentation have 

 as yet been discovered north of Argentina on the present 

 Atlantic slope of the American hemisphere." In quoting this 

 paragraph Professor Marcou apparently forgets that he, him- 

 self, has distinctly said in italics (Geology of North America, 

 p. 19), that " the Jurassic rocks do not exist on the Atlantic 

 slope of Worth America nor anywhere east of the Mississippi 

 RiverP My assertion of practically the same proposition is 

 maintained by every known fact, unless the Wealden beds, 

 which are not positively known to be marine and which are 

 classified with the Cretaceous by a preponderance of authority, 

 are Jurassic as maintained by Marsh — (merely a question of 

 classification, as I have recently shown in Science*). Further- 

 more, as he referred the Tucumcarri beds under discussion to 

 the " Oxfordian " and " Lower Oolite "f of the Jura, they are 

 in no manner to be confused with the Wealden, or "Jurassic" 

 of Marsh. Neither does the sentence quoted from me make 

 " a clean sweep of the American marine Jura," for it in no 

 manner alleges that there is no Jurassic on the Pacific slope, or 

 in the Black Hills of Dakota, where, as is well known, Jurassic 

 formations, in no manner related to those of New Mexico, so- 

 called by Professor Marcou, do occur. 



Concerning his general classification and tabular view of the 

 whole country south of the Arkansas, pp. 208-211, I will 

 state that it has no value and cannot in any manner be fitted 

 to known conditions. For instance, I have shown that the 

 Cheyenne Sandstone of Kansas which he places at the base of 

 his section, contains dicotyledonous flora and occurs stratigra- 

 phically about midway in the Lower Cretaceous of the Texas 

 section, and does not belong to my Trinity Division at all, as at 

 first supposed by Cragin. His "Tucumcarri Division (B) and 

 "Neocomian Division," are synchronous formations, and 

 embrace beds far more nearly allied to the Gault than Neoco- 

 mian. His descriptions of these divisions are purely imaginary 

 creations, stratigraphically incorrect, and altogether out of har- 

 mony with the natural occurrence of the rocks or the literature 

 thereon. The whole table is ingeniously constructed by com- 

 pilation of the works of the very authors he condemns. 



* December 18, 1896, pp. 918-922. f Geology of North America, pp. 19-20. 



