Glacial Landforms

Continental Glaciers

Striations Erosion of soil

Roches Moutonnees or sheepback

Weslemkoon Lake, Ontario Roche Moutonnee By The Lake

Moraines

Glacier Flow Terminal Moraine Material carried in the glacier like a conveyor belt is piled up in front of the ice sheet to form a moraine. The larger the moraine the longer the glacier is stationary, ie., in a state of mass balance. This material is till and is largely unsorted (ie., it is all mixed up with different sizes). Terminal moraines mark the maximum extent of ice advance.

Glacier Flow Terminal moraine If the climate changes and becomes warmer, the glacier will retreat and eventually achieve a new state of mass balance.

Glacier Flow Terminal moraine If the climate changes and becomes warmer, the glacier will retreat and eventually achieve a new state of mass balance. Note that even though the glacier is retreating, it is still flowing forward. It is just being ablated (melted) faster than it flows.

Glacier Flow When the new state of mass balance is reached, a new moraine is created, called a recessional moraine. For the skiers: Horseshoe Valley and Mt. St. Louis-Moonstone are on a recessional moraine. Terminal moraine Recessional Moraine

Sometimes two lobes of glacial ice come together and a moraine forms between them This happened north of Lake Ontario when there was a pause and short re-advance of the ice age during the last retreat – the ice lobe left in what would eventually become Lake Ontario grew north (and east and west and south) and met the main sheet moving south – they met just north of Toronto - the Oak Ridges Moraine – called interlobate moraine

Remnant ice sheet or chunk. “future” Lake Ontario basin Main ice sheet to the north The ice sheets in retreat … there is a pause...

Main ice sheet to the north “future” Lake Ontario basin …. and then a re-advance of the ice for a period of time

Main ice sheet to the north “future” Lake Ontario basin …. and then a re-advance of the ice for a period of time Oak Ridges - Interlobate Moraine

Lake Ontario Oak Ridges - Interlobate Moraine Toronto Kingston

Finger Lakes

Drumlins are egg-shaped hills oriented to the direction of ice movement – usually in clusters or field – about 200/300 in S. Ontario near Peterborough. Direction of ice movement m m Steep face indicates direction ice came from.

Drumlin

Rivers flowing under the ice sheet in tunnels carry a lot of sediment – some of the material gets deposited on the bottom of the tunnel – when the ice melted the long often windy pile of material is left – called an esker – because the flowing water tended to carry away the finer particles eskers are made of many sand and gravel and have been exploited for the aggregate industry. The flowing water of the melt water streams selectively sorted the sediments – finer particles laid down in lakes whereas coarser particles were left in rivers.

Erratics

Spillway with a Mistfit stream

Glacial Ponding When the ice sheets started to melt about 15,000 years ago, huge amounts of water poured off the ice and large lakes were created in front of the sheets – huge quantities of sediment were deposited in these lakes (called glacial ponds) – today they are large flat areas and have fertile soils – called lake plains – eg., Great Lakes Lowlands; southern Manitoba (Lake Aggasiz) and part of the Niagara Fruit Belt.

Glacial Ponding Sediments get deposited Weight of ice depresses the land As the ice begins to melt, meltwater collects in front of the ice. This is called glacial ponding

Glacial Ponding Sediments The ice age ends and the ice sheets retreat.

Glacial Ponding Sediments The ice age ends and the ice sheets retreat.

Sediments When ice retreats, land rebounds Glacial ponding drains away

Sediments When ice retreats, land rebounds Sediments remain behind and make for excellent soil. Called lake plains.

In some areas the ocean flooded inland quite a way during the period of ice retreat because the land was depressed from the weight of the ice – also created fertile areas, eg., St. Lawrence River valley lowlands – sand bars, etc. left behind.

Deranged Drainage Pattern

Alpine Glaciers

Cirque Arete Tarn Col Horn

Cirques, Aretes, U-shaped valley, Horns

Cirque

Arete

Col Horn

Tarns

V- Shaped Valley

U-Shaped Valley

This is a Fjord! The formation of a Hanging Valley.

Glaciers Sea level change and glacial lakes Video – New York City goes under Video – Climate Change

Glaciers Take the quiz and see how much you know about glaciers Video – Geography Glacier Quiz

The End!