22 THE ROYAL SOCIETY OF CANADA 
river. Even in the rapid stretches between the lakes the river has 
not cut any definite channel, and its waters often spread out for con- 
siderable widths on slightly depressed portions of the surface which 
are usually covered with boulders or angular masses of broken rock. 
An interesting method of formation of rapids, or obstructions 
was observed in this as well as in many of the smaller rivers of this 
part of northern Canada, though the most typical examples that came 
under my notice were on Machichi river. The ice, when it breaks 
up in the spring of the year, shoves boulders along the river bed 
until they form a curved ridge with a steep face down stream. Then 
the water overflows at one side or end of the boulder ridge, and cuts 
out a channel more or less at right angles to the general course of the 
stream. Such boulder-ridges may be formed across the whole channel 
of the river, or only across part of it. 
At Swampy lake, Hayes river enters a country covered with 
relatively soft Glacial and Post-glacial deposits that have filled the 
rock basins and buried the original hard rock surface under a soften 
superstratum of sand and clay. Swampy lake, which has an elevation 
of 500 feet above the sea, lies between ridges or plains of sand, and 
the river as it leaves it continues to flow over a bed of hard rock as 
before. The ridges are probably eskers, and possible also moraines, 
which were formed near the front of the Labradorean glacier during 
its retreat, rather than beach deposits formed on the shore of the ex- 
tended Hudson Bay. A little farther down the stream the Recent 
clays, etc., become more regularly distributed, and the river has cut 
a deep narrow channel through them. As far as a point six miles 
below ‘‘The Rock”’ the trenching of the valley has been carried down 
to the underlying hard rock, but below that point the rock has not 
been reached, and the bottom of the valley, as well as the sides, is 
composed of glacial or postglacial sands or clays. In places the banks 
are as much as 180 feet high, but they are everywhere steep, for there 
has been scarcely any wearing down of the adjoining country and from 
the top of the bank one looks down into a gorge-like valley in one 
direction, while in other directions the country extends as an appar- 
ently interminable moss-covered plain. Hayes river, here locally 
known as Hill river, continues northward in this deep narrow valley 
until it joins Fox river coming from the west, which, though not very 
much larger than Hill river, is flowing in a much more spacious valley. 
From the mouth of Fox river the united streams adopt its valley, 
and flow north-eastward under the local name of Steel river. Occa- 
sional cliffs of clay and sand overlook the outer sides of the curves of 
the stream, while within the curves are alluvial flats, behind which 
the banks rise by well-marked benches or terraces to the mossy 
plain above. 
