HISTORICAL REVIEW OF THE LARAMIE PROBLEM. 



35 



Bowen," Herald, 20 Hance, 21 Stebinger, 22 

 Beekly, 23 Wegemann, 24 Winchester, 25 and 

 others, the Lance formation was uniformly 

 classed as "Cretaceous or Tertiary." It is not 

 necessary to refer to these papers in detail, 

 except to that of Calvert, in which he recorded 

 certain facts of importance relating to a large 

 area in eastern Montana. He divided the 

 Lance formation of this area into two parts — 

 a lower sandstone member, immediately over- 

 lying the Pierre and named the Colgate sand- 

 stone member, and an upper or undivided 

 portion. As regards the line between the 

 Lance and the overlying Fort Union he said: 



In the area mapped the upper limit of the Lance forma- 

 tion can not be based on lithologic grounds but must 

 instead be dependent upon the occurrence of fossil Cera- 

 topsia bones . In the area treated in this report the highest 

 horizon at which these bones were found is just above the 

 lower persistent lignite bed, but there is certainly nothing 

 in the character of the overlying strata to suggest that 

 similar bones do not occur therein up through a strati- 

 graphic distance of perhaps 500 feet. * * * As a result 

 of these conditions no attempt is made on the index map 

 or on the maps of the various areas treated in this report 

 to differentiate the Lance formation from the overlying 

 strata described in connection with the Fort Union forma- 

 tion. * * * In other words, the area bounded on one 

 side by the contact between the Pierre shale and the 

 Colgate sandstone member and on the other side by the 

 outcrop of the lowest persistent lignite bed represents the 

 distribution of the Lance formation as mapped in this field'. 

 In this connection, however, it can not be emphasized too 

 strongly that the upper limit adopted is merely suggestive, 

 as the_ finding of Triceratops bones higher in the section 

 will necessitate an upward extension of the formation. 



At the meeting of the Paleontological Society 

 in Princeton, N. J., December 31, 1913, and 

 January 1, 1914, there was held a symposium 

 on the "Close of the Cretaceous and opening 

 of Eocene time in North America," which was 

 briefly introduced by Henry Fairfield Osborn, 

 and in which Messrs. Knowlton, Stanton, 

 Brown, Matthew, and Sinclair participated. 



i» Bowen, C. F., The Baker lignite field, Custer County, Mont.: Idem, 

 p. 202. 



>° Herald, F. A., The Terry lignite field, Custer County, Mont.: Idem, 

 p. 227. 



« Hance, J. H., The Glendive lignite field, Dawson County, Mont.: 

 Idem, p. 271. 



" Stebinger, Eugene, The Sidney lignite field, Dawson County, Mont.: 

 Idem, p. 284. 



» Beekly, A. L., The Culbertson lignite field, Valley County, Mont.: 

 Idem, p. 319. 



J< Wegemann, C H., The Sussex coal field, Johnson, Natrona, and 

 Converse counties, Wyo.: Idem, p. 441. 



»s Winchester, D. E., The Lost Spring coal field, Converse County, 

 Wyo.: Idem, p. 472. 



In the first paper 2C the following was given 

 as the thesis: 



It is proposed to show that the dinosaur-bearing beds 

 known as "Ceratops beds,'' "Lance Creek beds," Lance 

 formation, "Hell Creek beds," "somber beds," "lower 

 Fort Union," Laramie of many writers, "Upper Laramie," 

 Arapahoe, Denver, Dawson, and their equivalents are 

 above a major unconformity and are Tertiary rather than 

 Cretaceous in age. 



The evidence was presented under the 

 headings stratigraphic, paleobotanic, dias- 

 trophic, European time scale, vertebrates, and 

 invertebrates. In the discussion of strati- 

 graphic evidence it was held " that the dinosaur- 

 bearing beds above mentioned are separated 

 from underlying beds by a major uncon- 

 formity which makes the logical line of separa- 

 tion between Cretaceous and Tertiary." The 

 evidence bearing on the occurrence of this un- 

 conformity was traced throughout North and 

 South Dakota, Montana, Wyoming, Colorado, 

 and New Mexico and was demonstrated in a 

 number of ways, including angular and ero- 

 sional discordance, as well as faunal and floral 

 differences. 



The paleobotanic evidence was naturally 

 presented in extenso. It was shown that the 

 floras in the beds immediately below and 

 above the line of the unconformity comprise 

 about 350 species in the lower beds (Vermejo, 

 Laramie, Montana, etc.) and over 700 species 

 in the upper beds (Raton, Dawson, Arapahoe, 

 Denver, Lance, etc.) but that they have only 

 21 or 22 species in common, showing "that 

 more than 90 per cent of the Cretaceous flora 

 was wiped out by the disturbance attending 

 this diastrophic movement." 



In the Raton Mesa region of Colorado and 

 New Mexico the beds immediately above the 

 unconformity have been named the Raton 

 formation and contain a flora of 148 species, 

 only 4 of which are common to the underlying 

 Vermejo, which is below the line of the uncon- 

 formity. The Raton flora was correlated with 

 those of the Wilcox group of the Gulf coast 

 and of the Dawson, Arapahoe, and Denver 

 formations to the north. The correlation was 

 carried from the Denver Basin of Colorado 

 through North Park and into Carbon County, 

 Wyo., where the "Upper Laramie" of Veatch 



! « Knowlton, F. H., Cretaceous-Tertiary boundary in the Rocky 

 Mountain region: Geol. Soc. America Bull., vol. 25, pp. 325-340, 1914. 



