STRATIGRAPHIC POSITION OF JUDITH RIVER FORMATION 647 
according to Knowlton,’ is so widely recognizable. Referring to 
this mingling of forms at the base of the Lance, Knowlton says? 
Because Fox Hills fossils occur in the lignitic shales at the base of the 
“somber beds”’ and mingled with the brackish-water types of the Lance for- 
mation is not necessarily proof positive that the various faunas lived at the 
same time; for if the deposition. of the Fox Hills was followed by a definite 
erosion interval, what is more probable than that in the deposition of succeed- 
ing strata fossil shells would be eroded from the marine beds and carried into 
channels, there to mingle with the then living brackish-water fauna of the 
Lance formation ? 
A reference, at this point, to the Canadian section will be of 
interest as proving the existence of two series of fresh-water beds, 
the lower one of which was named the Belly River series by Dr. 
G. M. Dawson in 1882.3 He had previously described in his report 
on the geology and resources‘ in the vicinity of the 49th parallel 
an upper series of fresh-water badland beds lying south of Wood 
Mountain, which he referred to the Lignite Tertiary and an under- 
lying series thought to correspond to the Fox Hills group.s By 
the Lignite Tertiary, Dawson meant the Fort Union group of Hay- 
den; and he also correlated the beds with the Judith River beds. 
The same beds are later described as the Laramie (Edmonton and 
Paskapoo) by the other Canadian geologists. 
Later in his last report,® without having revisited the region 
south of Wood Mountain, Dawson relegated these beds to the 
Belly River series, and says: “‘ The beds thus separated as the Belly 
River series were, in 1875, by me, correlated with the Judith River 
series of the Missouri.’”’ Dawson had evidently been misled by 
the lithological resemblance between the two series. On p. 117¢ 
of the report just cited he says: ‘‘The Belly River series has 
1 Proc. Wash. Acad. Sci., XI (1909), 170-238;. Jour. Geol., XTX (1911), 360-776. 
2 Ibid., p. 365. 
3 Geol. Surv. Canada, Report for 1880-82, Montreal], 1883, pp. 1B-8B. On p. 1 
reference is made to a note published by Dawson in May, 1882, in which he says “‘the 
following report is essentially a reprint.” 
4 British North American Boundary Commission Report on the Geology and Resources 
in the Region in the Vicinity of the 49th Parallel, Montreal, 1875, pp. 103-58. 
5 [bid., p. 150. 
6 Geol. Surv. Canada, Report of Progress, 1882-84, Montreal, 1885, ‘‘ Report of the 
Region in the Vicinity of Bow and Belly Rivers, 1884,” pp. 118c f. 
