McGillivary Falls Self-Guiding Trail
Located off of Highway 44 just west of Caddy Lake, this 4.1 km
trail will lead you to a small drainage basin typical of the
Precambrian Shield. A short cut reduces the length of the trail to 2.4 km
before it reaches McGillivray Lake.
This particular type of drainage system and its associated characteristics are
found throughout Whiteshell Provincial Park. The controlling factor in this
pattern is the erosion-resistant bedrock of the area. The pattern is known as
deranged drainage and indicates the earlier activity of glaciers.
This small drainage basin is very similar to others in the park. River
systems such as the Whiteshell, Rennie, and even the mighty Winnipeg, are just
larger examples of the drainage system explored on this trail.
- The existence of McGillivray Falls indicates that this stream is relatively
young in terms of geological time, and that this is a primitive drainage system.
After many thousands of years, these waterfalls will erode down to a smooth
- The rock face on the other side of the falls has no water-line or other
marks of erosion by the stream. This is because the stream follows a natural
channel cut in the rock by the movement of glaciers, which melted away about
12,000 years ago. Had there been no natural depression, the stream would not be
flowing here, as the granite rock is very resistant to water erosion.
- Beavers bring about changes in drainage by building dams with branches
and mud. The dams create reservoirs in the stream, resulting in lower but more
constant flow downstream. For more information on the beaver visit the Picket
Creek Trail and the Whiteshell Museum at Nutimik Lake in the north end of the
- From this viewpoint you can see the natural depression in the bedrock. This
depression has been partially filled with material carried down by the stream
and washed in from all sides. It has taken thousands of years to reach this stage.
- You are standing on the remains of a dam built many years ago to hold back
spring runoff and maintain a higher waterlevel in McGillivray Lake. However, some
years ago part of the dam was removed to restore natural flow of the stream.
- McGillivary Lake and the bog through which the stream flows can be seen
from this ridge. Changes in the vegetation to the left of the stream indicate the
amount of water in the soil at different elevations.
- The several varieties of trees on this rocky slope indicate the varying
amounts of soil and water present. Jack Pine grows at the top of the ridge
where there is little soil and water runs off quickly. Dry ridges such as this
are extremely susceptible to fire in dry seasons. Where there is water draining
down the slope and more soil, birch, aspen and white spruce flourish. Where water
accumulates at the bottom, only bog plants and black spruce grow.
- This is McGillivray Lake. It is a typical lake of the Precambrian Shield
with a maximum depth of about three metres. The water is rich in nutrients,
algae and naturally occurring humic acid, giving the water its brownish tinge.
The lake is fed by two small streams and by run-off water. Lakes such as this,
with a small volume and a slow flushing action, are extremely sensitive to
- This black spruce bog is different in origin from the one seen earlier, beside
the stream. This bog is completely enclosed by rock ridges. Water accumulates
in this depression in the bedrock because it cannot drain away. Evaporation is
minimal because the water is held within the spongy sphagnum moss covering the
bog. A very moist habitat is thus created on what would otherwise be dry rock.
- You are now on top of a granite ridge which the trail follows to the
parking lot. Here the environment is dry because water drains away quickly.
Ridges such as this are usually dominated by jack pine, one of the few tree
species that can grow under these austere conditions.
The eventual destination of water in this drainage system is Hudson's Bay.
During its journey through the park it takes many forms, sustains plant and animal
communities, and provides the recreational opportunities for which the Whiteshell
is renowned. We must ensure that while water travel through the park, its potential
downstream is not impaired through our carelessness or misuse.
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