Continental Glaciers

Earth has experienced many episodes of dramatic climate changes with different periods in earth history. There have been periods during which the entire planet has been covered in ice and at another time it has been scorchingly hot and dry. In this regards, earth has experienced at least three major periods of long- term frigid climate and ice ages interspersed with periods of warm climate. The last glacial period which current glaciers are the result of it, occurring during the last years of Pleistocene, from approximately 110,000 to 10,000 years age (Clayton, 1997). Indeed, glaciers present sensitive indicators of climate change and global warming and by estimating and monitoring the dynamic evolution of these ice masses, several

The present configuration of the Great Lakes basin is the result of the movement of massive glaciers through the mid-continent, a process that began about one million years ago. . . . Studies in the Lake Superior region indicate that a river system and valleys formed by water erosion existed before the Ice Age. The Glaciers undoubtedly scoured these valleys, widening and deepening the and radically changing the drainage of the area (Encyclopedia Britannica )

The definition of glacial lake is any lake formed from glacial origin which would include Kettle lakes, kettle lakes are small lakes made by ice blocks left there from the glacier. Some evidence of glacial lakes in Minnesota are the large amounts of iron and sedimentary rocks and sediments. There are 6 major glacial lakes in Minnesota these lakes are Agassiz, Upham, Aitkin, Duluth, Grantsburg and Minnesota if there is another one I could not find it in the articles or online. The largest glacial lake is Lake Agassiz it covered a lot of Minnesota some of the Dakotas and lots of Canada it is truly the father of all glacial lakes, or at least it was. Glacial Lake Agassiz was drained by the Mississippi (the only answer I could find) and the water went into the Gulf of Mexico. Parts of this massive lake can be found in Lake Winnipeg, Lake Winnipegosis, and Lake Manitoba and

One major way Connecticut got its shape was from glaciation. For example, glaciation formed Jobs Pond. Jobs Pond is a giant kettle hole, which is a depression caused by the impact of a massive chunk of ice, or a glacier. According to The Mystery Of Jobs Pond, geologists and hydrologists the water level rises and falls with the groundwater level in the area, because porous sand and gravel make up the bottom of the pond. A kettle hole is formed by a glacier, so glaciation formed Jobs Pond. Another landscape formed by glaciation is recessional moraines. A recessional moraine is a pile of rocks left behind when a glacier recedes, or moves back. As a glacier moves, it picks up rocks in a process called plucking. Then, as the glacier starts to melt, it recedes. As it does this it drops off rocks, forming a recessional moraine. Recessional moraines, formed from glaciation, are found all along the Connecticut shoreline.

These formations caused the water level in many lakes to drop, and flow into rivers. With the weight of the glacier removed from the land, isotonic equilibrium occurred. The region began to rise, at a rate of about thirty centimeters per century (Leelanau, 2004). Water levels in the upper basin began to rise, forming lakes that filled the Michigan, Huron and Superior basins. Today, this isotonic rebound is still occurring, but at a rate of 53 centimeters per century. The rebound occurs at different rates across the area that was covered by the glacier. The difference in rates emerges from the difference in weight of the glacier. Areas that are rising the fastest today are those that had a thicker or heavier glacial ice, or those areas that had ice covering those most recently. Because of the difference in rates, the lower basin rose more slowly that the northern outlets (Leelanau, 2004). As the water changed directions to flow through the St. Clair River, the shape of the Great Lakes reached a point close to what they are at today. The shorelines and water level has changed, but the basic flow of water has stayed the same for the past 2,000 or so

During the Pinedale glaciation, there were two ice sheets. One of them being the Cordilleran Ice Sheet. The Cordilleran Ice Sheet was comprised of three main lobes. The Puget Lobe, Okanogan Lobe, and the Purcell Trench Lobe. The one lobe in Northern Idaho, near present day Lake Pend Oreille, was the Purcell Trench Lobe. When these sheets of glacial ice moved south they caused an ice dam to occur. J.T. Pardee states that “The evidence of icebergs, together with the apparent regency of the lake and the variable height of its surface, connect this lake with the glacial period, and readily lend themselves to the suggestion that its dam was of ice” (Pardee, 1910) This ice dam blocked the Clark Fork River which is near the boundary of Idaho and Montana. The water from the river was blocked and began to build up and formed Glacial Lake Missoula. Water

Running water moves sediment in the processes of erosion and deposition, causing different types of landforms. As you can tell in the picture above, Michigan’s topography plays a huge role on where the faster and slower flowing rivers are located and the transportation of the materials in the water depends on the speed of the rivers. Erosion is the breaking down of those materials by the agent, water. The water can erode the channel laterally and vertically, in the end, making the channel wider and deeper. There are different types of erosion: hydraulic action, corrasion, corrosion, cavitation, and attrition. Hydraulic action (above on the right) takes place at rapids and waterfalls because the force of the water removes rock particles from the bed and banks of the river. A great example of this in Michigan is Canyon Falls on the Sturgeon River. At the waterfall, the water is rushing at a high velocity, especially in the spring, causing rock particles to move downstream, creating a wider and deeper river. Eventually the rivers velocity begins to decrease and particles start to deposit. This could also occur because lack of precipitation or an increase in evaporation. The deposition of materials at different locations of the river that they began changes the shape of the river, and effects Michigan as a whole in the end. The particles can travel all the way to the mouth of the river, in this case, Lake Superior, causing

These drainage basins that formed 6,000 years ago are the origin of the Great Lakes we are familiar with today. These glacial lakes are thought to much larger than the current bodies of water surrounding Michigan. The evidence of these lakes can be found, for example, around Saginaw bay where there are eroded bluffs and plains located far away from the current Lake.

The Wisconsin Glaciation had effected Minnesota heavily, like it formed moraines that cover many different counties. The glacier also left lakes and drumlins. This glaciation was the most recent Glaciation in Minnesota, it still happened tens of thousands of years ago.

Lake deposits are primarily fine-grained clay- and silt-size sediments. The most extensive area of lake deposits is in north- ern Ohio bordering Lake Erie. These deposits, and adjacent areas of wave-planed ground moraine, are the result of sedimentation and erosion by large lakes that occupied the Erie basin as Wisconsinan-age ice retreated into Canada. Other lake deposits accumulated in stream valleys whose outlets were temporarily dammed by ice or outwash. Many outwash-dammed lake deposits are present in southeastern Ohio far beyond the glacial boundary. Peat deposits are associated with many lake deposits and formed through the accu- mulation of partially decayed aquatic vegetation in oxygen-depleted, stagnant water.

Michigan is well-known for the amazing Great Lakes that create its breath taking shoreline. The lakes contain about 23,000 km3 of water, covering a total area of 244,000 km2. The Great Lakes are a series of interconnecting fresh water lakes that hold 18 percent of the world’s fresh water supply, and 90 percent of the United States fresh water supply. The Great Lakes are made up by Superior, Michigan, Huron, Erie and Ontario. Superior, right off the coast of Marquette, is the biggest, deepest and coldest out of them all. The Great lakes didn’t just appear in the land on their own. They were formed by weathering, erosion, and deposition over ten-thousands of years ago, one-thousand years ago and hundreds of years

A glacier occurs when the climate of an area is so cold that new snow does not completely melt each summer and more snow is added in the winter. After many winters the accumulation of this snow becomes compact and re-crystallizes, thus forming a glacier. Currently, glaciers cover about ten percent of the Earth's surface. Yet, in the past, glaciers covered much more land and were thousands of meters thick. (Tierney)

Mauri Pelto, a glaciologist, studied a glacier on Mount Baker, in Washington State. The glaciers are melting, as the planet becomes warmer. “At the rate it is losing mass, it won’t make it 50 years,” said Pelto. Glaciers from Mount Baker and the North Cascades are getting smaller. Over the past thirty years, seven glaciers have melted. An estimate was made that the 116 glaciers that they studied in Alaska have lost a total of 75 billion metric tons of ice. There were 150 glaciers in Glacier National Park in 1850. Now, there are only 25."They are losing volume at a faster rate than ever before," Pelto said. "If you cannot sustain a glacier at a place like this in the Lower 48 states, there is no hope."

As said by a glaciologist with France’s Grenoble Alps University, Gael Durand, “the glacier has started a phase of self sustained retreat and will continue its decline.”The loss of ice from the glacier at this rate would cause disasters and hence is the latest issue of climatic concern.

The formation of the subglacial lakes in Antarctica is due to a mixture of physical processes which are also responsible for maintenance of the lakes. Water is thought to come from basal ice rising above its pressure melting point, helped by both geothermal heating below the ice and the thick ice above. The topography of the land beneath the ice sheets allows for the created water to flow into topographic basins and become a lake. Lakes can also appear on the flanks of mountains and at the beginning of large ice flows. Because the formation of water relies on the basal ice reaching its pressure melting point, it is found that most subglacial lakes have at least 3000m of ice above them. (Siegert, 2000; Kennicutt and Siegert, 2011; Davies, 2014, Riffenburgh, 2007) It is also typical of big lakes to have a flat ice sheet surface, as the basal ice’s frictionless contact with the water beneath removes shear stresses. (Siegert, 2000) It is common for the lakes to form where