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Roger Weller, geology instructor

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glaciers
by Kaylon Lull
Physical Geology
Spring 2011
                  

  

                       Glaciers    

 

            We live on an amazing planet, and one of the most amazing geological features on it is glaciers. Glaciers are extremely large chunks of ice that flow like a river but at a very slow speed, usually about a couple inches per year. These giant chunks of ice are formed by layers of snow stacking on top of each other and compacting the bottom layers into ice. If you’re looking to see a glacier in person you better pack your best winter coat because the only placeless they can live long enough to get that big are super cold places. Most of the glaciers in the world are in Antarctica and the North Pole. Greenland is a country near the North Pole that is almost completely covered in them. Although most of the glaciers are near the poles you can still find them in all the other continents except for Australia because the glaciers on other continents are in mountains at really high altitudes and Australia is a generally flat continent with no big mountain ranges.
 

                               Description: http://www.travelwithachallenge.com/Images/Travel_Article_Library/Alaska-Cruise-West/Tidewater-Glacier.jpg      
 

            Although it seems glaciers are a fairly simple structure they really are not. There is a long list of different types of them out there. Ice sheets are the largest glaciers, for a glacier to be considered an ice sheet; it has to cover at least 50,000 square miles. Ice sheets are only found in Antarctica and Greenland. Ice caps are smaller versions of ice sheets under 50,000 square miles that are usually found in high flat places.
 

                                Description: http://www.sciencemediacentre.co.nz/wp-content/upload/2009/05/glacier.jpg
 

          Next there are mountain glaciers that are only found in high mountainous regions. A valley glacier corresponds with the mountain type because they are usually found in high mountains but they flow down valleys, and sometimes reach sea level. The picture above is an example of a valley glacier. Piedmont glaciers happen when a steep valley glacier flows onto a relatively flat plane then spread out like a fan. Another type of glacier in the mountains is cirque glaciers. These glaciers occupy bowl like areas in the side of a mountain. Tidewater glaciers are glaciers that reach the ocean, and they originate as valley glaciers.
 

            Glaciers have a big effect on the geology of our planet. Glaciers have scraped across the earth for over a billion years making lots of changes to our surface. As a glacier flows across the ground it picks up lots of rocks along the way, this is called abrasion. The intensity of abrasion is mostly dependent upon the size, weight, and the speed that it is moving. Depending on these circumstances they can pick up boulders bigger than a city bus and carry them for their whole journey, then drop them in random places. While these rocks are still in the glacier they act like the grains sandpaper grinding away and smoothing the ground as they flow down a mountain valley. A byproduct of this sandpaper effect is something called rock flour which is rock that has been crushed by the glacier to a very fine grain. Often there is so much rock flour in glaciers that it gives the melt water a grey color. The rocks in the glaciers will sometimes leave big scrapes in the bedrock which is helpful to the scientist because it allows them to see which direction past glaciers were traveling and also where they have been.
 

            After a glacier moves across an area of bedrock it leaves its mark on the land by leaving things like drumlins, eskers, moraines and doing something called plucking. Plucking is when a glacier flows over the bedrock that already has cracks in it water gets in the crack and freezes then plucks the rock from the spot. It is usually from the back side of the bedrock.
 

                                          Description: http://upload.wikimedia.org/wikipedia/commons/thumb/9/95/Arranque_glaciar-en.svg/300px-Arranque_glaciar-en.svg.png
 

           A moraine is a deposit of random rocks and soil usually at the base of a mountain valley that is left behind from a glacier from the last ice age. Moraines can also be made from existing glaciers. Rocks and soil could be plucked by the glacier then dropped from the trailing end before it completely melts. Drumlins are a cigar shaped hill made of mostly till. When you find a drumlin you usually find more of them close by and that is called a drumlin field. A drumlin field gives scientist a good indication of where a glacier was and where it used to be. A good example of this is a drumlin field of about 10,000 drumlins east of Rochester, New York. This is good evidence that there were very large glaciers that far south in the past. It gives scientist good information to study and learn about the ice ages that have happened in the past. Eskers are long snake like ridges made of smaller rocks, pebbles, and soil that show the path of the glacier. They are thought to be formed from streams of melt water flowing under the glacier carving a tunnel that shapes the rock and dirt as it flows into the esker.
 

            Lots of things happened to the earth during the last ice age which was about 110,000 years ago. The cold took over the world and glaciers were a big part of it. The amount of ice on the planet changed earths air flow patterns, and level of precipitation. That helped form the planet into what it is today. From the rain forest to the desert, the last ice age changed things all over the world, but glaciers are still making their own changes to the planet today. As we get further away in time from the last ice age our planet heats up. Glaciers are melting at a faster and faster pace that adds more water to dry land and the ocean. this is a good and bad thing the good part is that glaciers are by far the largest reserve of fresh water, but the bad thing is that more water added to the oceans heats the water up which causes more natural disasters like hurricanes and it can also change the flow of the ocean current. This would seriously ruin the way ocean animals live. Lots would die and ruin the worlds fishing industry.
 

            Glaciers are beautiful, enormous, powerful, dangerous mysterious, and really exciting. In my opinion the preservation of the world’s glaciers should be on the priority list. Glaciers are a part of geology because geology is a science of studying and preventing disasters and glaciers have enough potential energy to destroy anything. 

 

 

Works Cited

https://nsidc.org/glaciers/questions/land.html

http://en.wikipedia.org/wiki/Glacier

http://geography.about.com/od/climate/a/glaciation.htm