212 



SCIENCE. 



[N. S. Vol. XVIII. No. 450. 



overlying ' Pierre shales ' on Sage Creek, Can- 

 ada, as described by Dawson and McOonnell 

 and continued our observations as far north 

 as the Cypress Hills, where the top of the 

 overlying marine Cretaceous is seen. Pass- 

 ing down Milk River below Havre and around 

 the eastern end of the Bearpaw Mountains 

 to Cow Creek and the Missouri River at Cow 

 Island and thence up to Dog Creek, Judith, 

 and Eagle Creek, Montana, we have studied 

 the typical areas of the Judith River beds 

 described by Meek and Hayden, and of the 

 Eagle formation described by Weed. 



We have become fully convinced that the 

 Belly River beds are identical with the Judith 

 River beds, as Dawson long ago suggested. 

 Our conclusion is based on lithologic char- 

 acter, stratigraphic sequence, the vertebrate 

 and invertebrate faunas of the beds them- 

 selves, as well as on the paleontology of the 

 underlying and overlying beds in both Canada 

 and Montana. We hope to present the evi- 

 dence in full in a more formal paper within 

 a few months. 



Another important result of our work is 

 the determination of the exact position which 

 these beds occupy in the general Upper Cre- 

 taceous section of the west. Eor many years 

 the Judith River beds have been generally 

 assigned to the top of the Cretaceous and cor- 

 related with the Laramie, while the Belly 

 River beds have been generally placed near 

 the middle of the Upper Cretaceous, above 

 the Benton and beneath the Pierre, though 

 Dawson did not assert that they underlie all 

 of the Pierre. We have found that the Judith 

 River beds underlie about 600 feet of beds 

 with the lithologic character and fauna of the 

 Pierre, and that beneath them there is an 

 equal thickness of marine beds that must also 

 be correlated with the Pierre on account of 

 the faunas they contain. Many of the in- 

 vertebrate species from the beds underlying 

 the Judith River have been described and 

 figured as ' Fox Hills ' species and supposed to 

 come from beds overlying all of the Pierre. 



On account of the differentiation of the 

 beds representing the Pierre in this region 

 into several formations, it is necessary to give 



new names to two of them which have not 

 been previously recognized. For the dark 

 clay shales with many calcareous concretions 

 immediately overlying the Judith River beds 

 we propose the name Bearpaw shales, since 

 they are well developed around the northern, 

 eastern and southern borders of the Bearpaw 

 Mountains. They have the lithologic and 

 faunal characters of the typical Pierre but 

 represent only a fraction of that formation 

 as generally understood. 



Beneath the light-colored, mostly non-ma- 

 rine Judith River beds is another formation, 

 400 feet in thickness, which in its lower half 

 resembles the Bearpaw shales and yields a 

 few of the same species of fossils. Its upper 

 200 feet, however, contain several sandstone 

 beds which bear a fauna that has hitherto 

 been called ' Fox Hills.' We propose the 

 name Claggett formation for these shales and 

 sandstones underlying the Judith River beds. 

 It is named for old Fort Claggett at the 

 mouth of Judith River, in the neighborhood 

 of which the formation is well developed. 



Beneath the Claggett is the Eagle forma- 

 tion (named by Weed in the Fort Benton 

 folio, Geologic Atlas of the U. S.) consisting 

 of several heavy beds of coarse, light-colored 

 sandstone, with clay shales and lignite, and 

 having a total thickness of 250 to 350 feet. 

 This also yields a marine fauna that has been 

 referred to the 'Fox Hills ' and is certainly 

 more recent than any Benton or Niobrara 

 fauna. 



The Eagle formation rests on dark shales, 

 which are known to include the Benton and 

 probably the equivalent of the Niobrara. 



The section may be summarized and com- 

 pared with the sections in South Dakota, 

 Colorado and elsewhere as follows: 



Ft. 



r Bearpaw shales 600 



J Judith Eiver beds 500-600 



Pierre i Claggett formation 400 



Eagle formation 250-300 



Niobrara I „ , , , , 



-, . V Colorado shales. | 



Benton J r 



J. B. Hatcher. 



T. W. Stanton. 



Judith, Montana, 



July 11, 1903. 



