116 B. N. A. BOUNDARY COMMISSION. 
of tbe beds included in it were truly lower than the dark Cretaceous clay- 
shales of No. 4, though noting the similarity of the series here exposed, 
with its light-coloured arenaceous clays, ironstones, and carbonaceous 
shales, to the beds of the Tertiary. Having afterwards examined the 
sections of the lower part of the Tertiary in Milk River, with which these 
are even more closely comparable, and finding there a species of Ostrea 
which appears to be indistinguishable from that represented by the few 
fragments obtained from bed No. 2,1 find it still more difficult to feel 
assured in referring these beds to a position inferior to No. 4 of the 
Cretaceous. Had they occurred apart from well-marked Cretaceous 
rocks, they would probably have. been referred, without doubt, to the 
Lignite Tertiary, in the absence of characteristic organic remains. 
283. To explain the present position of these beds, under the 
supposition that their age is Tertiary, it is necessary to suppose either an 
extensive overturn; or that they have been thrown down by a reversed 
fault, with an angle of only about 30°, nearly coinciding with the 
stratification, and carried beneath the edges of the undisturbed Cretaceous 
clays. Hither of these alternative circumstances is difficult to account 
for in a country so little disturbed, and where the strata are, as a rule, 
almost perfectly horizontal. If, however, the beds are truly Cretaceous, 
it still remains uncertain whether they should be considered as forming 
an important intercalation in No. 4, or whether they lie entirely below 
that division. The latter is the more probable supposition, as where the 
rocks of No. 4 are turned up against the flanks of the Buttes, further 
west, in such a manner as to reveal a great part of their thickess; though 
some thin layers of sandstone occur, nothing is found comparable with 
this series. 
284, The sandstones of these beds differ a little in aspect from 
most sandstones occurring in sections clearly referable to the Tertiary, 
being somewhat more uniform in their bedding, thinner leaved, and 
more equally hardened throughout. The carbonaceous shales of beds 6, 
and 12, are thinly cleavable, and might, in some places, be called impure 
lignite. One of the beds contains drops of amber, similar to those found 
in connection with many of the lignite beds elsewhere; and plant 
remains are abundant, but too poorly preserved for recognition. It is 
evident that where these carbonaceous shales were found, all the con- 
ditions which might lead to the accumulation of important beds of 
lignite obtained, and that such beds as these might be found, if followed, 
to widen out, or coalesce with each other within a short distance. The 


