532 AVGr PEASE 
In 1861 Meek and Hayden, after referring to the early conflict- 
ing views as to the age of the Judith River beds, say:* ‘‘They are 
really of Tertiary age, and hold a position at the base of the great 
lignite series [Fort Union formation] of the northwest.” . In 1871? 
Hayden gave these deposits the name “Judith group,” and says: 
The sediments do not differ materially from those of the Fort Union group, 
and they contain impure beds of lignite, fresh-water mollusca, and a few leaves 
of deciduous trees. But the most remarkable feature of this group is the 
number and variety of the curious reptilian remains of which we have only 
yet caught a glimpse. 
As to the age of the underlying sandstones near the mouth of 
the Judith River, concerning which there had previously been some 
doubt, both Meek’ and Hayden‘ in 1875, independently of each 
other, correlated them with the Fox Hills, Meek saying that “‘we 
cannot be far wrong in regarding the latter beds [the marine Cre- 
taceous beds at the mouth of Judith River] as holding a position 
at the horizon of the top of the Fox Hills.”’ Cope,’ in 1874, in a 
‘“‘review of the vertebrata of the Cretaceous period found west of 
the Mississippi River,” in a notice of the Judith River beds under 
the head of the Fort Union or lignite group, says: ‘‘ From the stand- 
point of the writer, these beds would be at the top of the Cretaceous 
and more or less related to the Fort Union epoch.’’ After the early 
explorations by Hayden, the first geological examination of the 
Judith River country was made by Edward S. Dana and George 
B. Grinnell® in the summer of 1875. They made a short excursion 
to the mouth of the Judith River and spent two days in this locality. 
They speak of their results being, of course, meager. ‘‘ Enough,’ 
however, was seen to establish the age of the beds at this point as 
beyond a doubt Cretaceous, three members of this division of Meso- 
* Proc. Acad. Nat. Sci., 1861, p. 415, footnote. 
2F, E. Hayden, Preliminary Report, U.S. Geol. Surv. Wyoming, Washington, 
LOLs Oye 
3 Bull. U.S. Geol. and Geog. Surv., I, 2d series, No. 1, p: 39. 
4 Ibid., p. 403. 
5 Bull. U.S. Geol. and Geog. Surv., 1874-75, I (1875), 1st series, p. 6. 
6 Geological report in Ludlow’s report of a Reconnaissance from Carroll, Montana, 
on the Upper Missouri, to the Yellowstone National Park and Return, Washington, 1876. 
7 [bid., p. 124. 
