HISTORICAL REVIEW OF THE LARAMIE PROBLEM. 



33 



Stratigraphy of the central part of the Bull Mountain coal 

 field, Mont. 



The Laramie (?) was regarded as the equiv- 

 alent of the "somber beds" of the Miles City 

 field. 



The Buffalo coal field, Wyo., was described 

 in this bulletin by H. S. Gale and C. H. Wege- 

 raann. In tliis area the dinosaur-bearing beds 

 were referred to the so-called Piney formation, 

 which was said to be pre-Tertiary or Cretaceous 

 [both terms are used in the report], though some 

 doubt was expressed as to whether tliis designa- 

 tion would prove to be correct. 



In 1910 T. W. Stanton " published a short 

 paper dealing with this subject and recording 

 new field data from areas in the Dakotas and 

 eastern Wyoming. The term Lance formation, 

 wliich has now come into such general usage, 

 was here published for the first time and was 

 specifically stated to be a substitute for the 

 old terms "Ceratops beds," " Lance Creek beds," 

 and equivalents. Of the three areas discussed 

 in this paper the one first considered was the 

 Standing Rock and Cheyenne River Indian 

 Reservation^ or the region between Grand and 

 Caimonball rivers in North and South Dakota. 

 In tliis area attention was directed principally 

 to the Fox Hills sandstone and its contrast 

 with overlying beds, and a number of sections 

 were given, together with lists of the inverte- 

 brates found. vStanton said : 



At the top of the Fox Hills sandstone with its purely 

 marine fauna there is a rather tliin but widely distributed 

 brackish- water bed, which contains Ostrca, Anomia, Cor- 

 bicula, Melania, etc., in great abundance. The zone in 



" Fox Hills sandstone and Lance formation (" Ceratops beds") in South 

 Dakota, North Dakota, and eastern Wyoming: Am. Jour. Sci., 4th ser., 

 vol. 30, pp. 172-188, 1910. 



which this fauna occurs varies in thickness from 3 or 4 feet 

 up to 40 feet and is lithologically very similar to the under- 

 lying marine beds, but its base is irregular at many places 

 and shows channeling and other evidences of erosion. It 

 was therefore regarded by the field geologists as the basal 

 member of the overling Lance formation resting uncon- 

 formably on the Fox Hills. In the study of this brackish- 

 water bed evidence was found at several localities, dis- 

 tributed over a considerable area, that there is a distinct 

 transition without a break of any importance between the 

 marine Fox Hills sandstone and the brackish-water de- 

 posit. The paleontologic evidence consists of distinctive 

 Fox Hills species belonging to such marine genera as 

 Scaphilcs, Lunatia, and Tancredia, found directly associated 

 in the same bed with the brackish-water forms and occur- 

 ring with them in such a way that they must have lived 

 together or near each other and been embedded at the 

 same time. 



The second area included the valley of the 

 Little Missouri from Marmarth to Yule, N. 

 Dak. The point emphasized with reference to 

 this area was the finding of an oyster bed some 

 500 feet above the base of the Lance formation 

 and above all the dinosaurs that have been 

 found in the region. 



The Lance Creek area in Converse County, 

 Wyo., which had been reexamined in company 

 with M. R. Campbell and R. W. Stone, was the 

 tliird area considered. Of this area Stanton 

 said: 



Our principal contribution to the knowledge of the 

 stratigraphy of the area was the discovery that the marine 

 Fox Hills deposits extend about 400 feet higher than had 

 previously been determined, and that nonmarine coal- 

 forming conditions were temporarily inaugurated here 

 before the close of Fox Hills time. 



In conclusion Stanton wrote: 



The three areas discussed in this paper, taken together, 

 tell a story of gradually changing conditions near the end 

 of the Cretaceous, when the uplift of the Rocky Mountain 

 region was draining the interior sea. The uplift was not 

 uniform nor continuous, and the emergence above sea 

 level could not have been simultaneous for all localities 

 throughout the region. * * * The bearing which the 

 facts here presented have on the Laramie problem is self- 

 evident. If it is true that there is a transition with prac- 

 tically continuous sedimentation from the Fox Hills sand- 

 stone into the Lance formation in the region dLscussed, 

 then the Lance formation includes or forms part of the 

 Laramie. 



The first published official statement showing 

 that the discussion concerning the age of the 

 Lance formation was having its effect is to be 

 noted in a short report on the eastern part of 

 the Bull Mountain coal field, Mont., by C. T. 

 Lupton.'-'' Here for the first time the Lance 



" U. S. Geol. Survey Bull. 431, p. 163, 1911. 



