HISTORICAL REVIEW OF THE LAKAMIE PROBLEM. 



53 



belong to the Livingston, as plants identical with those 

 found neir the bise of this formation southeast of Bozeman, 

 Mont., have now been located, and moreover the matrix 

 is characteristically that of the Li^nngston. Between 

 this point and the base of the upper member of the Fort 

 Union formation, according to Stanton, is a thickness of 

 3,000 to 5,003 feet of beds, a portion of the lower pirt of 

 which belongs with little doubt to the LiWngston, but 

 the top of the Livingston has not been definitely placed, 

 though its maximum thickness appxrently exceeds 2,000 

 feet. The dinosaurs occur in this thick series of beds 

 above the Livingston, and the beds are probably referable 

 to the lower member of the Fort Union, though no plants 

 have been found until within approximately 1,000 feet of 

 the top. 



Later in the same year (1909) T. W.Stanton "» 

 published still another interpretation of the 

 Fish Creek section. After discussing briefly 

 the units of the Montana group and their 

 thicknesses as worked out by Stone, he 

 continued : 



Another important fact brought out by Stone's work 

 is that the ''Laramie" of Weed's mapping east and north 

 of the Crazy Mountains in the Little Belt Mountains folio 

 is really Eagle sandstone, and the "Livingston" of the 

 same area includes in its lower part the Claggett, Judith 

 River, and Bearpaw formations. The Li^dngston forma- 

 tion was described as resting unconformably on the 

 Laramie and older rocks and as composed largely of 

 andesitic material, both of which features played a promi- 

 nent part in correlating the Li^dngston with the Denver 

 formation. It became necessary, therefore, to study the 

 lithologic character of the various formations of the 

 Montana group in this area. * * * The specime:is 

 from the Eagle and a few of those from the Claggett and 

 Judith River proved to be sandstone without admixture 

 of igneous material, but many others from T)0th Claggett 

 and Judith River and some from the Bearpaw are identi- 

 fied as tuffaceous rock and contain much andesite. 



After discussing a number of collections of 

 invertebrates from beds originally supposed to 

 be Laramie but here shown to bei from the 

 Claggett, Stanton said: 



With the facts above recited in mind, the whole ques- 

 tion of the age and relations of the Living.ston formation 

 is reopened. * * * Whatever may be true of the 

 Li\'ingston in the type area near the town of that name, 

 the rocks assigned to it by Weed east of the Crazy iloua- 

 tains, notably in the Lebo Creek section, certainly belong 

 to several distinct formations ranging in- age from well 

 down in the Cretaceous to the lower Eocene. 



The thick series of beds referred provisionally 

 to the Laramie by Stone and including in part 

 at least the Fox Hills ? and Laramie of Douglass 

 were next considered. The paleontologic evi- 



'» The age and stratigraphic relations of the " Ceraiops beds" of 

 Wj-oming and Montana: Washington Acad. Sci. Proc., vol. U, pp. 

 255-265, 1909, 



dence included dinosaurs (Triceratops and 

 others), fresh-water invertebrates, which "in- 

 dicate close relationship with the fauna of the 

 Ceratops beds of Hell Creek and Converse 

 County," mammals, and plants. 



From what has preceded it is of course 

 evident that the previously accepted status of 

 the Laramie and Livingston formations in the 

 region under discussion had been brought 

 seriously in question. The newer data bear- 

 ing on the problems involved were presented 

 in an important paper by Stone and Calvert "' 

 under the title "Stratigraphic relations of the 

 Livingston formation of Montana," in which 

 the following was given as the thesis: 



It is the purpose of this paper to show (1) that the coal- 

 bearing formation of the Li\nngston section is not Laramie 

 but is Eagle or at least lower Montana in age; (2) that the 

 andesitic beds above, known as the Li\'ingston formation, 

 are not separated from the underlying formation by an 

 unconformity anywhere within the area discussed; and 

 (:?) that their peculiar lithologic character is not a criterion 

 of specific age but is a shore phase of many formations 

 ranging from Colorado to Fort Union, inclusive. 



Some of the main points advanced in this 

 paper may be briefly enumerated. First, in 

 regard to the Laramie as identified by Weed, 

 Peale, and others, Calvert, in studying the area 

 between Red Lodge and Livingston, observed 

 an especially well exposed Mesozoic section on 

 Boulder River in T. 2 S., R. 13 E., where he 

 found invertebrates that were pronounced by 

 Stanton to be of Colorado age at a horizon 300 

 feet below the lowest coal. Several similar 

 collections were obtained on Trail Creek, near 

 Electric, and elsewhere, from a horizon "very 

 near the top of beds previously considered 

 Montana," all being considered as Colorado. 

 As this determination does not leave room for 

 the thick Montana section between the Color- 

 ado and the "Laramie" coal measures, and 

 moreover, as no time interval has been noted 

 between them, the conclusion follows, accord- 

 ing to Calvert, that the coal measures must be 

 well down in the Montana. "At Livingston 

 the section shows about 800 feet of coal 

 measures, underlain by about 3,700 feet of 

 Colorado shale, as measured below Yellow- 

 stone Canyon." This thickness of 3,700 feet 

 accounts for the thickness assigned by Weed 

 to both Colorado and Montana. 



" stone, R. W., and Calvert, W. R., Econ. Geology, vol. 6, pp. 551- 

 557, 6.i2-669, 741-764, 1910. 



