/ 



/ ' 



>D 



42fi FLORA OF TlIK LARAMIE GROUP. 



fyiiif,^ not only as settling tlie question at issue, but as silencing criti- 

 cism of tlie value and reliability of the general work acconiplislied by 

 the survey under my direction." But in this same letter Dr. Ilayden 

 also declares his conviction, more than once before expressed, but not 

 as yet, so i'ar as I know, accepted by either Lesquereux or Newberry, 

 " that the Fort Union beds of the Upper Missouri River are the equiva- 

 lent of the Lignitic formation as it exists along the base of the Kocky 

 Mountains, in Colorado," as well as of the Bitter Creek series west of 

 the Eocky Mountains, as argued by Dr. White, and he says: " It is 

 also probable that the brackish-water beds ou the Upper Missouri must 

 be correlated with the Laramie, and that the Wabsatch group as now 

 defined and the Fort Union group are identical as a whole, or in i)art 

 at least." 



As Mr. Lesquereux's conclusions expressed in this report are the same 

 as he had held throughout the discussion, and the arguments not new, 

 no further elucidation of them is necessary. 



Volume I of Mr. Clarence King's Geological Eeports of the Survey of 

 the Fortieth Parallel, treating of the systematic geology, and written by 

 Mr. King himself, did not appear until 1878. His views upon this ipies- 

 tion were looked for with great interest, though it was, of course, to be 

 expected that they would coincide generally with those of his assistants 

 already published in other volumes. Notwithstanding the tendency, 

 which had been marked for several years, to regard the attempt to as- 

 sign the Laramie group to either the Cretaceous or Tertiary age as not 

 only profitless but rather puerile, inasmuch as its relative position in the 

 western American system was so well settled, Mr. King did not consider 

 it beneath the dignity of this stately report to approach the subject 

 much from the old standpoint and record his position in nearly conven- 

 tional terms. He says (p. 3.50) : "Aside from the Taconic system, no 

 single geological feature in all America has ever given rise to a more 

 extended controversy than the true assignment of the age of this group. 

 On data which will presently be set forth, it is assumed by us to be the 

 closing member of the Cretaceous series, and the last group of the 

 great coulbrmable system which east of the Wahsatch stretches upward 

 from the base of the Cambrian." 



The views that had been i)ut forth in opposition to tliis he then ar- 

 ranges into a series of seven " assumptions," which he proceeds to con- 

 sider and dispose of in the order laid down. As some of these points 

 are admitted and others not vital, they need not be noticed seriatim; a 

 few extracts must suffice. He says (p. 352) : "A complete refutation of 

 assumption three, that the fauna proves a Tertiary, not a Cretaceous age, 

 is found in the fact that the evidence of a meagre molluscan life and a 

 large range of plants cannot be held to weigh against the actual pies- 

 ence of Dinosauria in the very upjicrmost Laramie beds, and, as will 

 appear in the sequel, of an abundant lowest Eoeene mammalian fauna in 

 the unconformably overlying Vermilion Creek group. » * * As- 



