10 FLORA OF THE MONTANA FORMATION. 
According to Dr. G. M. Dawson, the discoverer and namer of this 
somewhat anomalous series of coal-bearing beds, the stratigraphic 
position of the Belly River series is between the Colorado and Montana 
formations. If this is strictly true, it would obviously be out of place to 
consider the flora of these beds in connection with that of the Montana 
formation, except, perhaps, for purposes of comparison. Other obser. 
vers, however, would regard the Belly River series as synchronous, in 
part at least, with the Montana formation, and one geologist, Dr. C. 
A. White, 1 inclines to the opinion that it is completely so, thus passing 
from the top of the Colorado to the base of the Laramie. 
The Belly River series, which takes its name from the Belly River, 
a tributary of the South Saskatchewan, has, according to the Canadian 
geologists, a large areal extent. It is found occupying the surface in 
the Canadian districts of Assiniboia, Saskatchewan, and Alberta, 
extending for a distance of about 300 miles. It is composed of sand- 
stones, clays, shales, and important coal seams, and has a maximum 
thickness of fully 1,000 feet. 
As long ago as 1886 the presence of this formation in the United 
States was suggested by Mr. W. Lindgren, 2 who noted the presence of 
strata in the upper part of the valley of the Musselshell River in 
Montana which, although referred by him to the Laramie, in all proba- 
bility belong to the Belly River. 
In August, 1883, Dr. C. A. White and Prof. Lester F. Ward also noted 
the presence of certain plant-bearing strata on the Missouri River, 
about. 7 miles below the Coal Banks, below the mouth of Bear Creek, 
which belong, with little doubt, to the Belly River series. They made 
at this time a small collection of fossil plants, which I have studied 
and incorporated descriptions of in the following pages. 
Mr. T. W. Stanton and Mr. W. H. Weed visited this same locality 
in 1894, and Mr. Stanton has kindly prepared the following notes on 
its stratigraphy and paleontology: 
On the Missouri River near Fort Benton the dark shales of the Fort Benton forma- 
tion are exposed. The same formation is seen for many miles down the river, hut as 
there is a slight dip in that direction, higher beds are in turn exposed, and some of 
those that have usually been called Fort Benton are now recognized by the fossils to 
more nearly represent the Niobrara. The beds gradually become more sandy, and 
in the upper portion of the shales forms are found that seem to be intermediate be- 
tween the Colorado and Montana formations. Immediately above this zone is a 
massive light-colored sandstone, 100 feet or more in thickness, associated with coal 
seams and ferruginous bands. This is exposed at Coal Banks and for many miles 
below. The fossil-plant locality on the right bank of the river, 7 miles below Coal 
Banks, must be just above this sandstone. Farther down the Missouri, near the moutn 
of Arrow River, the dark Fort Pierre shales, with a characteristic fauna, are clearly 
seen to overlie the sandstone, and still above that comes the section near the mouth 
of Judith River, as published by Cross from my notes, 3 which includes the Fox Hills 
or Upper Montana and the Judith River beds, which are true Laramie. We were not 
'Bull. U. S. Geol. Survey No. 82, p. 176 (1891). 
2 Tenth Census U. S., Vol. XV, pp. 743-746. 
3 Geology of the Denver Basin : Mon. U. S. Geol. Survey Vol. XX, p. 240. 
