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Glaciers & Glaciation
Transcript of Glaciers & Glaciation
Paleoclimatogists are quite involved with glaciers as that they use ice cores to study of changes in climate taken on the scale of the entire history of Earth.
Average earnings of a climatologist is from $66,000 to $74,000, but can earn up to $117,000 on the higher end
Minimum requirement is a bachelor's degree in atmospheric science, although post-graduate studies are strongly recommended in this field. Questions Thank you for listening! Glacial Lakes Kettle Lakes Ribbon Lakes Glacial Valleys Roches Moutonnées Cirque Glacial Striae & Trim Lines Arêtes & Horns Outwash Fan Kames Moraines Erratics Eskers & Drumilins Glaciers Glaciation Development Types & Movement Abrasion & Plucking Glaciers are thick masses of ice that formed over hundreds and thousands of years.
Are the accumulation of the compaction and recrystallization of snow, originating on land.
Has a fundamental role in both the rock and water cycles.
It serves as an erosional agent that transports and deposits sediments, called glacial till.
Earth's largest freshwater resource, supporting a third of the world's population
Currently covers 10% of Earth's
surface Even with their massive size, glaciers facing significant problems due to global warming and climate change.
This is causing an accelerated glacial retreat, with minimal advance during winter months.
The destruction of the this important freshwater resource will foreshadow rising sea levels, causing devastating effects on coastal areas Glaciation is the movement of an ice sheet over a land surface. Glaciers move very slowly.
Two types of glaciation:
Continental glaciation affects a broad section of a continental land mass, such as Antarctica.
Alpine glaciation is usually restricted to deep valleys in high mountainous terrain.
Defined as either advancing or retreating:
Glacial advance is when the terminus (end of the glacier) moves forward faster than it melts, the net result is advance.
Glacier retreat occurs when more material ablates from the terminus than is replenished by flow into that region. http://media.pearsoncmg.com/bc/bc_0media_geo/interactiveanimations/038_GlacProcess_SP_GL_Stu.html?te10#/ Turning Snow into Ice Wasting & Calving Budget Zone of accumulation & wastage http://media.pearsoncmg.com/bc/bc_0media_geo/interactiveanimations/035_GlacAdvRet_SP_GL_Stu.html?te10 Terminus Fallen snow on glacier eventually turns to solid ice due to pressure of overlying layers of snow
Firn are rounded granules of snowflakes that acts as cement for the newer and loosely formed ice
This process leads to the development of thick slabs of glacial ice As mass of glacial ice increases, glacier begins moving down slope due to gravity, called flow
Wasting (or ablating) is when the flow of glacial ice reaches farthest point and is "wasted" though melting.
Calving is the process in which large blocks of ice break off from glacial face and plunge into water as an iceberg. Budget is defined as the ratio between ice gained and lost
Positive budget is when glacier gains more volume in new snow than snow lost, causing an advancing glacier
Negative budget is when glacier loses more volume than gaining, causing a receding glacier Zone of accumulation is the upper elevation of a glacier continuously covered in snow, where snow accumulates.
Zone of wastage lower elevations of glacier were snow is lost or "wasted"
Snow line is the irregular boundary between these; moves down glacier in positive budget and up it during a negative budget The front of the glaciers or terminating point (end point) of the glacier
It moves down the valley during a positive budget and up the valley during a negative budget
Terminus is usually one of the areas of glaciers with most deposition Two main types of Glaciers:
Valley Glaciers (or Alpine) are masses of ice restricted to high elevation valleys, in mountains.
Can move up to 15 metres a day, valley glaciers tend to move quickly due to steeper slopes and a layer of water over underlying rock, called basal sliding
Ice Sheets are associated with continental glaciation and cover large areas of landmass, existing in Greenland and Antarctica
An ice sheet moves down slope in multiple directions from a central area of high altitude. The ice sheet must expand because of the constant accumulation of ice and snow and move slower than valley glaciers due to more mass and less slope Glaciers erode terrain through two principal processes: abrasion and plucking
Plucking is a glacial phenomenon which erodes and transports bedrock. Friction is caused by glacier moving down valley floor This friction causes ice to melt and enters joints in the bedrock where it then freezes. As the glacier moves on, the rock now bonded to the glacier, plucked from the bedrock and carried with it. These plucked rocks can also cause abrasion against the bedrock and walls
Abrasion is the grinding of rock surface by friction between rock and moving particles by glaciers commonly characterized by striations. The ice and its load of rock fragments slide over bedrock and function as sandpaper, smoothing and polishing the bedrock below, leads to steeper valley walls Glacial striation are scratches or gouges cut into bedrock by glacial abrasion. Usually multiple, straight and parallel representing movement of glacier using rock, even polishing the rock.
Trim lines are a clear lines on the side of a valley formed by a glacier. Easily made visible by different colours due to rock or vegetation. Glacial Striations at Mount Rainer National Park Trim lines at Tana Glacier, Alaska Roche moutonnée (or sheepback) is a rock formation caused by passing glacier.
The passage of glacier ice over underlying bedrock often results in asymmetric erosional forms as a result of abrasion on the up-ice side of the rock and plucking down-ice side. "Sheepback" in Cadir Idris, Wales. Can you tell which direction the glacier moved? Cirque is a landform found among mountains as a result of alpine glaciers.
It is a concave shape on the downhill side of slope formed when glacial debris combine and converge from the three or more higher sides.
This ends up turning the surrounding area into a bowl-shape.
The highest side of the cliff is called the headwall and the side from which glacier flowed away is called a sill or threshold. Glaciologists study formation and composition of glaciers, ice caps, snow and permafrost.
Conduct research, collect samples and perform experiments to understand the effect snow and ice has on Earth's climate. For example ice cores are the most common samples taken
A senior research position in glaciology makes a salary of $56,301, with reimbursement of 25% of living expenses
The minimum educational requirement for glaciologists is a bachelor's of science degree in geology
Employment as a field researcher or a post secondary instructor requires a master's or doctoral degree in glaciology. Geologist studies the matter which makes up the Earth, the processes and history involved which shaped it.
Examine and identify rocks and minerals. Prepare maps that show rock types and geological structures
Earnings range from $35,000 to $150,000 a year or more and depend on location, experience, and education
At minimum a bachelor’s degree in geology or a related field
Many senior and research positions require a master’s degree or PhD Bibliography
"GPH 111 - Glaciation." GPH 111 - Glaciation. N.p., n.d. Web. 26 Feb. 2013. <http://www2.pvc.maricopa.edu/ssd/geog/outlines/GPH111/18_glaciers.html>.
"Geology: Introduction to Glaciation." Geology: Introduction to Glaciation. Cliff Notes, n.d. Web. 20 Feb. 2013. <http://www.cliffsnotes.com/study_guide/Introduction-to-Glaciation.topicArticleId-9605,articleId-9517.html>.
"Glacier." Wikipedia. Wikimedia Foundation, 26 Feb. 2013. Web. 22 Feb. 2013. <http://en.wikipedia.org/wiki/Glacier>.
"Topic Page:." Glaciers. Credo Reference, n.d. Web. 23 Feb. 2013. <http://www.credoreference.com/topic/glacier>.
"Geology: How Glaciers Develop." Geology: How Glaciers Develop. Cliff Notes, n.d. Web. 20 Feb. 2013. <http://www.cliffsnotes.com/study_guide/How-Glaciers-Develop.topicArticleId-9605,articleId-9519.html>.
"The State and Evolution of Canada's Glaciers." Government of Canada, Natural Resources Canada. Natural Resources Canada, n.d. Web. 25 Feb. 2013. <http://www.nrcan.gc.ca/earth-sciences/climate-change/landscape-ecosystem/impacts-landmass/4849>.
Laurentide Ice Sheet. YouTube. YouTube, 03 Jan. 2011. Web. 26 Feb. 2013. <https://www.youtube.com/watch?v=wbsURVgoRD0>.
Glacial Advance and Retreat. Glacial Advance and Retreat. Person Education, n.d. Web. 18 Feb. 2013. <http://media.pearsoncmg.com/bc/bc_0media_geo/interactiveanimations/035_GlacAdvRet_SP_GL_Stu.html?te10>.
Glacial Landforms Erosion | Glacier Melting and Calving | Animated Kids (Children) Education Video. YouTube. YouTube, 19 Sept. 2012. Web. 26 Feb. 2013. <http://www.youtube.com/watch?v=0nlBwhCK0CE>.
Bowen, Colin. "Glacial Landforms." Colarado Education. Colarado Education, n.d. Web. 16 Feb. 2013. <http://www.colorado.edu/geography/class_homepages/geog_1011_sum08/GlacialLandscapes_Bowen.PDF>.
"(af). Landforms of Glaciation." 10(af) Landforms of Glaciation. University of British Columbia Okanagan, n.d. Web. 19 Feb. 2013. <http://www.physicalgeography.net/fundamentals/10af.html>.
"Glaciologist." Occupational Profiles -. ECO Canada, n.d. Web. 25 Feb. 2013. <http://www.eco.ca/occupationalprofiles/profiles/glaciologist/25/>.
"Hydrologist." U.S. Bureau of Labor Statistics. U.S. Bureau of Labor Statistics, n.d. Web. 25 Feb. 2013. <http://www.bls.gov/ooh/life-physical-and-social-science/hydrologists.htm>.
"What Is Geology? - What Does a Geologist Do?" What Is Geology? Geology.com, n.d. Web. 26 Feb. 2013. <http://geology.com/articles/what-is-geology.shtml>.
"Climatologist." Occupational Profiles -. ECO Canada, n.d. Web. 25 Feb. 2013. <http://www.eco.ca/occupationalprofiles/profiles/climatologist/79/>. Hydrologists study the water, its movement, distribution, and quality.
Look at the hydrologic (water) cycle, water resources and environmental watershed sustainability.
Involved in industries such as hydroelectric power, flood prevention, and agriculture
Average salary is around $35,000 to $130,000
The minimum requirement is a bachelor's degree in hydrology
For senior and academic/research positions a graduate or PhD degree is required Land surveyor use specialization equipment and computerized mapping systems to analyze land surface.
Land surveyors in the arctic are used to analyze the elevations and structures which make up this landscapes.
Average salary ranges from $35,000 to $100,000 a year .
A diploma or bachelor's degree is require in surveying engineering, and license to practice in specific jurisdictions U-shaped valleys are carved by glaciers moving down slope transforming the original V-shaped. These valleys have steep walls, flat basin, and till carried by glacier is deposited at valley floor.
Hanging valleys is a tributary valley with the floor at a higher relief than the main channel into which it flows. The main glacier erodes the main valley while small tributary glaciers erode shallower U-shaped valleys
Fjords are formed as U-shaped valleys, but when glacial melting occurs Earth's crust begins to rebound, and when near an adjacent sea the water flows into the valley Arêtes are thin, knife-like ridges of rock usually formed when two glaciers erode parallel U-shaped valleys. It is the edge that forms between.
Arêtes can also form when two glacial cirques erode headwards.
The ridge is sharpened by freeze-thaw weathering, and the slope on either side of the arête steepened through the erosion of exposed, unstable rock.
Glacial Horns (or pyramidal peak) is a sharply-pointed mountaintop produced by the erosion of multiple glaciers converging on a central point.
Typically formed in drainages on sides of mountains, develop into cirques, 3 or more converging cirques on a central point will cause the formation of horns Matterhorn, Mount Cervin Arête, is the french word for "edge" or "ridge" Moraine-dammed Lakes Eskers are long winding ridges of stratified sand and gravel (glacial till) occurring due to glaciation.
Formed with ice-walled tunnels which flowed within and under glaciers. After the retaining ice walls melted away, stream deposits remained as long winding ridges.
Can form above glaciers by accumulation of till in glacial channels, in crevasses, the linear zones between stagnant blocks
Drumilins are elongated hills in the shape of an inverted spoon formed by glacial ice acting on underlying unconsolidated till or ground moraine.
Drumlin creation occurs by a significant flooding release of highly pressurized water flowing underneath the glacial ice
Tend to be 1-2km long, less then 50m high, and 300-600 wide Drumilin Esker Kame is an irregularly shaped hill or mound composed of sand, gravel and till that accumulates in a depression on a retreating glacier, and is then deposited on the land surface with further melting of the glacier.
With the melting of the glacier, streams carry sediment to glacial lakes, building a delta (stream flowing through and around glacial ice and depositing material) on top of the ice.
However, with the continuous melting of the glacier, the kame delta eventually collapses on to the land surface. Outwash fan is a fan-shaped body of sediments deposited by braided streams from a melting glacier.
Sediment locked within the ice of the glacier, gets transported by the streams of meltwater, and deposits on the outwash plain, at the terminus of the glacier.
The outwash, the sediment transported and deposited by the meltwater and that makes up the fan, is usually poorly sorted due to the short distance traveled before being deposited. Erratic is a piece of rock that greatly differs from the size and type of rock native to the area in which it rests.
These rocks can give the geological history of the path and lithographic origin of a glacier and its sediments.
Form by the cracking of very large pieces of bedrock which is then plucked, transported, and then deposited Big Rock in Okotoks Alberta weights 15,000 tons Lateral Moraine Terminal Moraine Moraine any glacially formed accumulation of unconsolidated glacial debris (till) occurring in glaciated regions.
The glacial debris has been plucked off the valley floor as as the glacier advances or fallen of valley walls, and when it melts or deposited the till is deposited
Moraines may be composed of debris ranging in size from silt-sized glacial flour to large boulders Ground Moraine Medial Moraine Lateral moraines are parallel ridges of debris deposited along the sides of a glacier. The debris can be deposited on tops of glaciers by erosion of the valley walls and/or from tributary glaciers.
The till is carried along until the glacier melts.
Because lateral moraines are deposited on top of the glacier, they do not experience the post-glacial erosion of the valley floor and therefore, as the glacier melts, lateral moraines are usually preserved as high ridges. Terminal moraines, are ridges of debris deposited at the snout or end of the glacier, and they usually reflect the shape of the glacier's terminus.
Glaciers act much like a conveyor belt, carrying debris from the top of the glacier to the bottom where it deposits it in end moraines.
The longer the terminus of the glacier stays in one place the more debris will accumulate in the moraine. Ground moraines are till covered areas with irregular topography and no ridges, often forming gently rolling hills or plains.
It is accumulated at the base of the ice as till, but may also be deposited as the glacier retreats.
Are often found between the two lateral moraines. Ground moraine may be modified into drumlins by the overriding ice. Medial moraine is a ridge of moraine that runs down the center of a valley floor.
It is formed when two glaciers meet and the debris on the edges of the adjacent valley sides join and are carried on top of the enlarged glacier.
As the glacier melts or retreats, the debris is deposited and a ridge down the middle of the valley floor is created. Glacial lakes are lake with origins of a melted glacier.
The scouring action of the glaciers pulverizes minerals in the rock over which the glacier passes, and when it melts, escaping water fills the hole or space that they have created.
Near the end of the last glacial period, roughly 10,000 years ago, glaciers began to retreat, and when finally melted they are created glacial lakes.
Examples of glacial lakes are the Great Lakes which are glacial basins of melted ice from the Laurentide Ice Sheet of the last ice age. Kettle lakes (kettle hole, pothole) are a shallow, sediment-filled bodies of water formed by retreating glaciers or draining floodwaters.
Result of blocks of ice calving from the front of a receding glacier and becoming partially to wholly buried by glacial outwash.
Glacial outwash is generated when streams of meltwater flow away from the glacier and deposit sediment to form broad outwash plains
When the ice blocks melt, kettle holes are left in the outwash plains Moraine-dammed lake occurs when a terminal moraine has prevented some meltwater from leaving the valley. Its most common shape is that of a long ribbon, but not always. Ribbon lakes are long and narrow, finger-shaped lakes, usually found in a glacial trough.
Forms glacier moves over an area containing alternate bands of hard and soft bedrock, which the glacier erodes more quickly by abrasion, thus creating a hollow called a rock basin.
On either side of the rock basin, the more resistant rock is eroded less and these outcrops of harder rock are known as rock bars, which act as dams between which when they melt fill these basin creating ribbon lakes. Freshwater & Great Lakes Carving of the Landscape Fertility & Soil Glaciers and Glaciation has had a significant impact on Canada, its landscape and much more.
Its has formed much of the landscape around us, from a walk outside to driving on the highway outside of the city it is easy see the effect it has had.
Three significant impacts glaciers have had on Canada are: Great Lakes are form the largest group of freshwater lakes on Earth, containing 21% of the world's surface fresh water.
As stated earlier, the Great Lakes are glacial basins of freshwater caused by the retreat of glaciers in the last ice age.
This is the main reason way the surrounding areas of the Great Lakes are so heavily populated as it support enough water from them. Cities like Toronto, Detroit, Chicago, and Buffalo lines these regions.
They serve as key waterways for transport of goods and such. Remnants of glacial till, has distributed minerals across Canada due to this Canada has some of the most fertile soils for agriculture
It has also left large mineral deposits like Potash, which Canada is the largest exporter of in the world. Glaciers have carved the landscapes of Canada, in Ottawa it only takes a simple walk to Gatineau Park to see the impact glaciers have had on this wonderful landscape, glacial landforms can be found in many places
The Canadian Shield is an example of an area with significant impact from glaciers, it has been scoured by glaciers leaving igneous bedrock behind, with winding rivers and landforms
Glaciers can still be found in Canada in the Rocky Mountains and in the high Arctic.