204 The American Geoloyist. October, i89(> 
graphic series exposed in eustern Montana, from the Dakota 
upward, yet along the Rocky mountain front the coal-bearing 
Laramie beds are succeeded by a great series of beds that are 
of peculiar lithological character and possess a distinct flora 
nearly identical with that of the post- Laramie Denver beds of 
(Colorado, jind show in several places marked unconformity 
with the Laramie, both stratigraphically and in the composi- 
tion of the conglomerates found in the series. This series of 
beds the writer designated as the Livingston formation,* and 
the conclusions as to its age and relation to the Laramie have 
been confirmed Vjy conclusive evidence gathered by Dr. A. (\ 
Peale, in the vicinity of the Gallatin valley. f 
To clearly understand the importance of the Livingston and 
of its occurrence between the Laramie and Fort Union forma- 
tions, the evidence may be summarized as follows: The Liv- 
ingston formation is post- Laramie. It is formed chiefly of 
assorted and water-worn volcanic material, rests unconform- 
ably upon Laramie and all the earlier Cretaceous terranes of 
the region, and includes conglomerates, recording a pro- 
longed period of post-Laramie uplift and erosion; it is char- 
terized by a flora of post-Laramie type and by a purely fresh- 
water fauna. 
Fort Uiu'o)! Forinatlon. The plant and invertebrate re- 
mains characteristic of the strata at the type localit}' consti- 
tute a peculiar flora and fauna. The characteristic species of 
this locality have been recognized in the beds overlying the 
Livingston formation near the Crazy mountains; and as this 
is the only region known where the Cretaceous, including the 
Laramie formation, is succeeded by both the Livingston and 
Fort Union formations, its occurrence here will be described 
somewhat fully. 
In the region north of the Yellowstone river, less than 100 
miles north of the National Park, the imposing group of peaks 
known as the Crazy mountains is the most conspicuous fea- 
ture of the landscape. These mountains are formed of T^iving- 
ston beds, conformably overlain by a series of sandstones and 
clay-shales, characterized by fresh-water fauna, and lithologi- 
*Buli. 105, U. S. G. S. 
tThree Forks, Montana, Geological folio of the U. S. Ge(jlogical Sur- 
vey. 
