Glaciation
Continental Glaciers
-covers a continent, and moves under its
own weight
-gives the landscape a smooth, rounded
appearance
-last glaciation period happened 1 to 2
million years ago and ended around
100,000 to 10, 000 years ago
-Greenland and Antarctica are the only
places in the world that have continental
glaciers today.
Alpine Glaciers
-occurs only in mountainous areas
-moves down slope because of gravity
-gives the landscape a rugged, jagged
appearance
-we have alpine glaciers all over the
world today. In Canada, the most famous
is the Columbia Ice Field (BC and Alberta
border).
Erosional Features
Striations – can occur with both
continental and alpine glaciers. Rocks
along the bottom of the glacier scrap the
bedrock like sandpaper and create large
scratches.
Spillways – also occur with both types of
glaciers. As the glaciers starts to melt the
water collects to form large rivers and
these rivers create deep wide valleys.
Depositional Features
Till – material of clay, sand and gravel
that is dumped by the glacier as it melts.
Moraines – these are ridges of till that
are left by the glacier at its snout, and
sides. They may be many in an area, as
the glacier advances and retreats.
Drumlin – an ‘egged’ shaped hill created
by a glacier. One end is steep and the
other side gentle slopes downward.
Erratic – A large boulder picked up and
moved thousands of km away and then
deposited by a glacier.
Esker – a ‘s’ shaped hill. Looks like a
snake from an aerial view. Created by a
river flowing underneath the glacier.
Glacial Features in Southern Ontario
Moraines
Ingersoll – an east-west ridge of till deposited by the edge of a glacier when it stop
moving for a period of time, runs along Commissioners Rd (Warbler woods to
Ingersoll)
Arva/Brescia – was deposited by two glaciers pushing against each other 10,000 to
20,000 years ago, part of the moraine runs through the university and north
towards Lucan.
Kettle Ponds
Sifton Bog – the bog depression was once occupied by a large block of ice. It left as
the last glacier melted around 13,000 years ago. Under the vegetation is a thick peat
layer, which rests on the stony soil or till which surrounded the ice block. When the
block melted, the depression or kettle remained. The glacial deposits are about 25 m
thick and cover limestone bedrock about 375 million years old.
Westminister Ponds – the ponds occupy kettle depressions made by large blocks of
ice, which left when the last glaciers started melting 13,000 years ago. They occur in
the Ingersoll moraine and pieces of white chert and black from the till are still found
by the ponds.
Glacial Lake
Lake London – melt water from the glacier was trapped by ice and moraines the
water collected in the valley between the two moraines to form Lake London. The
Thames River is all that is left from this old lake. In places you can see evidence from
the deposits of the lake, silt and clay have been eroded by creeks and mudslides,
forming steep slopes and ravines around the Thames R.
Spillways
Meadowlily Woods – is situated within a glacial spillway carved by meltwater
through the Ingersoll moraine. Over thousands of years, three distinct terraces have
been carved into the moraine’s north-facing slope by the erosive forces of the
Thames.
The Medway Valley – is an ancient spillway carved by glacial melt water through the
Arva moraine. The riverbank displays clear traces of the two glaciers. The river
meanders across the spillway, continually eroding its banks and exposing layers of
stony mud, (till, formed at the foot of the glacier), mud, sand and gravel. Stones in
the banks and river comprise several rock types derived from bedrock throughout S.
Ontario and the Canadian Shield. The glacial deposits are about 25m thick and
cover limestone bedrock formed in tropical seawater 375 million years ago.