384 Rk. BELL—HUDSON BAY MAMMOTH AND MASTODON REMAINS. 
Missinaibi, from Moose factory,* which stands about 7 miles in from the 
mouth, is southwest for 127 miles to Round bay, at the foot of the Ar- 
cheean plateau, where it turns south. The rate of rise in the river-bed 
from the head of tide, 9 miles above Moose factory, to this point is esti- 
mated to be between 3 and 4 feet to the mile, which would make the ele- 
vation at the end of this distance between 400 and 500 + feet above sea- 
level. In this interval the river flows with a pretty uniform and rather 
swift current, interrupted by stony rapids here and there. The banks 
consist exclusively of till and stratified drift, resting directly upon Silu- 
rian and Devonian limestones, which slope almost imperceptibly toward 
the bay or at only about the same rate as the river-bed itself. 
The name Moose river belongs properl¥ to only the trunk stream below 
the junction of the Missinaibi, or western branch, with the Mattagami, or 
central branch, at the above mentioned 46 miles from the factory; but 
as the traveled route to the Canadian Pacific railway follows the former 
branch, it is sometimes referred to under the same name. The general 
- height of the cut-banks of the river increases from 10 or 20 feet at Moose 
factory to about 140 feet at the end of the 127 miles referred to, but often 
for considerable distances the country is low on one side or the other, 
and sometimes on both sides. The usual height of the cut-banks is from 
30 to 50 or 60 feet. Their lower parts appear to be composed, in most 
cases, of blue clay, sometimes soft and sticky, with or without rounded 
pebbles. The central stratum, which constitutes the major portion of the 
banks, consists of bluish-gray and drab clays, with boulders and pebbles. 
The marine shells washed out of the banks appear to be derived from 
beds of pebbly drab clays associated with this division. The upper por- 
tions of the deposits consist of beds of gravel and sand, with brownish 
gravelly and bouldery earth towards the top. 
The clays near the mouth of the river contain upward of a dozen spe- 
cies of marine shells, some of which indicate tolerably deep water ; but 
in ascending the stream the deep-water species disappear, and at last only 
the shore and the shallow-water shells remain, such as Saxicava rugosa, 
Macoma calcarea, M. grenlandica, Mytilus edulis, and Mya truncata. Some 
of these shells were found as far as Round bay, at the extremity of the 
long southwestward stretch of the river above referred to. Marine shells 
were also observed along the Mattagami from its mouth up to the foot of 
the Grand rapids, a distance of 39 miles, and at an altitude which is prob- 
ably only a little lower than that attained by these shells on the Missi- 
naibi. The species last seen on the Missinaibi were Saxicava rugosa and 
* Factory, the residence of a chief factor or agent. 
+ In my Geological Survey Report for 1877, p. 7 C, a lower estimated elevation was mentioned, 
but subsequent observations render it probable that this is more nearly correct. 
