GGR100 ± Chapter 17 Textbook Notes 1 amazonaws com
cc
À
While the former mentioned agent of erosion is water, the second is ice. Ice is restricted primarily to glacial periods, high latitude or high elevation
À
c are large masses of flowing land ice (always moving). The glacier is fed from snow precipitation, which pushes it downslope. Glaciers form when temperatures are low couples with adequate snowfall.
À
c move under the pressure of their own great weight and the pull of gravity. When snow doesn¶t melt between summer and winter, the snow pile grows while the lower levels of snow compact. This leads to a material called firn also known as glacial ice causing the ice to pressurize and lose rigidity. This loss of rigidity allows the glacier to freely move over rocks and surfaces without breaking. The immense weight from the glacier moving severely erodes the ground underneath as it flows crushing and transporting material downslope.
À
Mass balance determines whether a glacier is growing or shrinking.
À
If a glacier is in equilibrium, ablation (zone of evaporation and sublimation) is equal to accumulation (system input as snowfall). But glacial ice continues to flow. Ablation is balanced in equilibrium. The accumulation zone ends at the firn line.
À
0 u areas high in the mountains marked by trails of transported debris. Several types of moraines are exhibited.
À
£ u form along each side of a glacier
À
u form at the end of the glacier
À
mark temporary positions of the ice margin
cc
è
À
0 are glacially eroded formations from glaciers. Terminal moraines are a result of glaciers melting and depositing unsorted debris.
À
The oak ridges moraine is an erosional landform
À
^ u a glacier in a mountain range is an alpine glacier. Alpine glaciers create mass wasting, weathering, fluvial procesesu V-shaped valleys and have thick soil. Glaciation causes the steepening of cirque and valley walls. There is also intense erosion as the glacier crushes plucks and abrades. Ice recession causes exposure of troughs, hanging valleys and tarns.
À
are also known as ice sheets. Ice accumulation begins in the upland and as the ice thickens it begins to spread outwards. This can lead to accumulations of blanketing (ice sheets).
cc
6
À
Glaciers form two types of streamline hills, and . The erosional is called roche moutonnee (sheep rock) and the depositional is called a drumlin.
À
0 ! (depositional landforms) created by continental glaciation described belowu
À
M are extensive deposits of stratified sands and gravels deposited by large braided river systems.
À
are subglacial streambeds that can be turned into gravel beds. Eskers are formed from flowing water underneath a glacier.
À
c ! is the generic term for all glacial deposits, both unsorted and sorted
À
describes direct ice deposits left by the glacier as unstratified and unsorted debris.
À
ë " is materials that have been transported by meltwater and thus sorting by particle size has taken place
À
c" also takes place and this is when deposition in proglacial lakes takes place to sort it out.
cc
w
À
Loess refers to wind
À
The last time ice sheets covered the majority of southern Ontario was around 12000 years ago.
# À
c are affected by global climatic change and redistribution of vegetation and biomes and last long time periods of around 100,000 years.
À
$ ` Fluctuations in global sea levels are a result of glaciers melting causing sea levels to rise
À
¦ $ ` is the change in relative sea level due to local effects of ice accumulation
À
Sea levels in the past were much lower because much of the water was locked up in glaciers that had not yet melted
À
¦ are the periods of brief warm spells that interrupt glacial periods and usually only last about 20,000 years.
À
© $u refers to last 2000 years
À
Causes of climate change are external and internal processesu Ô u solar processes and orbital changes Ô ¦ u plate tectonics, ocean currents, volcanism, greenhouse gases, feedbacks, human activity
À
Causes of the glacial/interglacial cycling according to Milutin Milankovitch (Astronomical Theory)
À
The 3 following cycles determine growth and shrinkage of ice sheets according to Milankovitch.
À
0 u Eccentricity ± earth¶s elliptical orbit about the sun is not constant. The degree of the ellipticalness of the Earth¶s orbit around the sun determines glacial periods.
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{
À
0 %u Obliquity/Axial tilt - the axial tilt is important for summer and winter lengths for glaciers as the planet shifts 2 degrees over 40 thousand years which is enough to control seasonality leading to ice ages
À
0&u Wobble ± earths axis wobbles in a movement much like that of a spinning top winding down. The wobble is called precession.
À
Ice coring gives ratios of oxygen isotopes, air bubbles explain concentration of atmospheric gasses, and concentrations of dust, annual ice accumulation and melt water that recrystallizes.
À
Fossil pollen and paleovegetation accumulate in lake sediment. Pollen helps to understand vegetation, which explains many factors of past climates. As ice began to shrink with ablation, we saw that the spruce could move and recolonize in areas that were formally covered with an ice sheet.
À
While the former mentioned agent of erosion is water, the second is ice. Ice is restricted primarily to glacial periods, high latitude or high elevation
À
c are large masses of flowing land ice (always moving). The glacier is fed from snow precipitation, which pushes it downslope. Glaciers form when temperatures are low couples with adequate snowfall.
À
c move under the pressure of their own great weight and the pull of gravity. When snow doesn¶t melt between summer and winter, the snow pile grows while the lower levels of snow compact. This leads to a material called firn also known as glacial ice causing the ice to pressurize and lose rigidity. This loss of rigidity allows the glacier to freely move over rocks and surfaces without breaking. The immense weight from the glacier moving severely erodes the ground underneath as it flows crushing and transporting material downslope.
À
Mass balance determines whether a glacier is growing or shrinking.
À
If a glacier is in equilibrium, ablation (zone of evaporation and sublimation) is equal to accumulation (system input as snowfall). But glacial ice continues to flow. Ablation is balanced in equilibrium. The accumulation zone ends at the firn line.
À
0 u areas high in the mountains marked by trails of transported debris. Several types of moraines are exhibited.
À
£ u form along each side of a glacier
À
u form at the end of the glacier
À
mark temporary positions of the ice margin
cc
è
À
0 are glacially eroded formations from glaciers. Terminal moraines are a result of glaciers melting and depositing unsorted debris.
À
The oak ridges moraine is an erosional landform
À
^ u a glacier in a mountain range is an alpine glacier. Alpine glaciers create mass wasting, weathering, fluvial procesesu V-shaped valleys and have thick soil. Glaciation causes the steepening of cirque and valley walls. There is also intense erosion as the glacier crushes plucks and abrades. Ice recession causes exposure of troughs, hanging valleys and tarns.
À
are also known as ice sheets. Ice accumulation begins in the upland and as the ice thickens it begins to spread outwards. This can lead to accumulations of blanketing (ice sheets).
cc
6
À
Glaciers form two types of streamline hills, and . The erosional is called roche moutonnee (sheep rock) and the depositional is called a drumlin.
À
0 ! (depositional landforms) created by continental glaciation described belowu
À
M are extensive deposits of stratified sands and gravels deposited by large braided river systems.
À
are subglacial streambeds that can be turned into gravel beds. Eskers are formed from flowing water underneath a glacier.
À
c ! is the generic term for all glacial deposits, both unsorted and sorted
À
describes direct ice deposits left by the glacier as unstratified and unsorted debris.
À
ë " is materials that have been transported by meltwater and thus sorting by particle size has taken place
À
c" also takes place and this is when deposition in proglacial lakes takes place to sort it out.
cc
w
À
Loess refers to wind
À
The last time ice sheets covered the majority of southern Ontario was around 12000 years ago.
# À
c are affected by global climatic change and redistribution of vegetation and biomes and last long time periods of around 100,000 years.
À
$ ` Fluctuations in global sea levels are a result of glaciers melting causing sea levels to rise
À
¦ $ ` is the change in relative sea level due to local effects of ice accumulation
À
Sea levels in the past were much lower because much of the water was locked up in glaciers that had not yet melted
À
¦ are the periods of brief warm spells that interrupt glacial periods and usually only last about 20,000 years.
À
© $u refers to last 2000 years
À
Causes of climate change are external and internal processesu Ô u solar processes and orbital changes Ô ¦ u plate tectonics, ocean currents, volcanism, greenhouse gases, feedbacks, human activity
À
Causes of the glacial/interglacial cycling according to Milutin Milankovitch (Astronomical Theory)
À
The 3 following cycles determine growth and shrinkage of ice sheets according to Milankovitch.
À
0 u Eccentricity ± earth¶s elliptical orbit about the sun is not constant. The degree of the ellipticalness of the Earth¶s orbit around the sun determines glacial periods.
cc
{
À
0 %u Obliquity/Axial tilt - the axial tilt is important for summer and winter lengths for glaciers as the planet shifts 2 degrees over 40 thousand years which is enough to control seasonality leading to ice ages
À
0&u Wobble ± earths axis wobbles in a movement much like that of a spinning top winding down. The wobble is called precession.
À
Ice coring gives ratios of oxygen isotopes, air bubbles explain concentration of atmospheric gasses, and concentrations of dust, annual ice accumulation and melt water that recrystallizes.
À
Fossil pollen and paleovegetation accumulate in lake sediment. Pollen helps to understand vegetation, which explains many factors of past climates. As ice began to shrink with ablation, we saw that the spruce could move and recolonize in areas that were formally covered with an ice sheet.
