! ! ! s r e i c a l G f o r e d n o W e Th By: Shehim Mekuria-Miller, Tessa Williams, and Emma Picard
The Wonder of Glaciers! By: Shehim Mekuria-Miller, Tessa Williams, and Emma Picard
This book is dedicated to, Ms. Bull,
Ms. Erickson, and Karin Gravina for helping us out with this book and putting up with us.
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Hello, my name is Julia. The two girls by my side are Abilene in the red, and Aliyah in the blue scarf. Together, we are The Glacier Girls, otherwise known as TGG. We hope that you enjoy our book!
Bonjour!
Shalom!
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Shalom! My name is Aliyah, and I am going to tell you about the two main types
of glaciers: continental glaciers and mountain glaciers. I am also going to tell you about the different types of mountain glaciers: valley glaciers and cirque glaciers Continental Glaciers You are about to learn a lot! So be prepared to be filled with glorious information on continental glaciers. Did you know that continental glaciers are also called ice sheets? Continental glaciers cover continents. Well, actually let me be more specific than that, continental glaciers are found on only two continents: Antarctica and North America. The Greenland ice sheet, which is in the North Pole covers an area of about 670,000 square miles and the Antarctic ice sheet which is found in the South Pole covers 5.4 million square miles. The Antarctic ice sheet is 15,000 feet thick in some places. That’s the size of 10 Empire State buildings!
Continental Glaciers Greenland ice sheet
Antarctic Ice Sheet 3
Mountain Glaciers Did you know that mountain glaciers are found all over the world? To be specific, mountain glaciers are found on mountains. Mountain glaciers are usually long and narrow. They are also thousands of feet wide and many miles long. There are two main types of mountain glaciers. They are valley glaciers and cirque glaciers. Let me tell you about them both!
Mountain Glacier
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Valley Glaciers Valley glaciers form in the place they are located-valleys. As the glaciers slide down the valley, they drag sharp rocks and ice with them, cutting the valley sides and forming a valley. Valley glaciers are commonly originated from mountain glaciers and ice fields. Valley glaciers can be very long.
Valley Glaciers
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Cirque Glaciers Cirque glaciers are located on high mountainsides or at the top of valleys. Cirque glaciers are located in cirques. A cirque is a space between two peaks that is shaped like a bowl. Cirque glaciers are one of the smallest types of glaciers. Unlike valley glaciers, cirque glaciers tend to be wide rather than long. Well, now you know about the main types of glaciers, but you need to move on and learn with Julia about how glaciers form.
Cirque
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Hi! I’m Julia, and I'm going to tell you how glaciers form. In order to form a glacier, first you need snow. The snow then turns to firn (firn is little balls of ice) and then to glacial ice. Conditions to Form a Glacier To form a glacier, first you need to have a very cold place because snow is the main thing that you need. The snow has to stay all year round. There also has to be a lot of snow. Glaciers form above the snow line. The snow line is where the snow never melts.
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Snow Changes in a Glacier New snow has about 80% to 90% air in its snowflakes. After a while, the snow changes because the weight of the new snow squishes together or compresses the old snow. This pushes the air in the snowflakes out. In about a year, the snow compresses and is then only 50% air. Firn and Glacial Ice After 2 years, the snowflakes turns into firn or little balls of snow or ice. Firn is the stage in between snow and ice. Firn has 20% air, much less than snow. The weight of the new snow on top of the glacier compresses the air out of the firn and it becomes glacial ice.
How a Snowflake becomes Glacial Ice Each snowflake goes through several steps as it becomes glacial ice. The first step is that the snowflakes’ points evaporate making a gas called water vapor. The second step is that the water vapor fills the air pockets of the snowflakes. Step three is that the water freezes and turns the snowflakes into little balls of ice. Now it’s called firn. The final step is that the heavy new snow on top compresses the firn together. The air gets squished out of the firn and the firn becomes glacial ice. The glacial ice is blue because most of the air is squished out. Now that you know all about how glaciers form, Abilene is going to tell you how glaciers move. 9
Snow
Firn
Glacial ice
Soft-like putty
Stages of Glacial Ice Formation
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Bonjour, I am Abilene. Did you know that glaciers move? Not only will I tell you about the movement of glaciers, I will also tell you about the landforms glaciers create. So let’s get started!
First let’s talk about how glaciers move. Glaciers first start to move when they are around 30 meters (100 Ft) thick. The movement of a glacier is called flow. One way a glacier moves is called basal sliding. Basal sliding is when rocks and water is at the base or bottom of the glacier. The layer of water is very thin. The water makes the glacier slippery and it slides down the surface it is on. The water melts because it is touching the surface of the earth. It makes the bottom of the glacier hot and it melts. Another way the water melts is friction. When the glacier moves, it creates friction. Friction makes the bottom of the glacier hot so the water melts into a thin layer of water and slides down the slope. 11
Another way a glacier moves is called plastic flow. The more weight a glacier has on top of it, the more it starts to moves because of the weight. The ice crystals inside move at different speeds and very slow speeds. It is so cool that there are two different ways for a glacier to move!
Want to know something really cool? The under side of a glacier moves slower than the top part. Here is why. The bottom of the glacier is closer to the surface of the mountain or slope, so the rocks scrape against the bottom causing it to move slower than the top. The top and bottom are not the only parts of a glacier that move at different speeds. The middle of a glacier moves faster than the edges as well. It seems almost impossible for the two things to happen at the same time! 12
Now let’s talk about how fast or how slow glaciers move. Most glaciers travel slowly, about 30 cm per day. A fast moving glacier can flow up to 20 meters (70 Ft) per day. Some even flow up to 50 meters (160 Ft) per day! I thought glaciers moved way slower than that! Water makes it easier for a glacier to slide. Some of the other things that affect a glacier’s speed are the temperature, the steepness of the slope, and the thickness of the glacier. Now that you know all about how glaciers move, let’s talk about the landforms glaciers create from moving. Trust me this WILL be cool, NOT boring.
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Let’s start by talking about moraine. When ice melts from the glacier, it leaves behind rocks and sediment called moraine. One of the types of moraine is called ground moraine. Ground moraine is material at the bottom of the glacier. It is found at the valley floor when ice melts. Moraine is cool right!
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Plucking changes the earth. Plucking is one way a glacier creates landforms. Here is how. Plucking is when melted water at the sides and base of a glacier freezes into rock surrounding the glaciers. When the glaciers move, the rock in the glacier gets pulled away. It leaves the surface with big holes called basins which you will later learn about.
The glacier moves and the rocks it collects go with it. The rocks move with the glacier. They are getting pulled away by plucking.
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I know your mind is about to explode from all this information, but there is more to know.
U-Shaped valley
Here are some of the landforms glaciers create. Glaciers can create arêtes (a jagged ridge), pyramidal peaks, U-shaped valleys, and Vshaped valleys. Glaciers created most of the landforms we have today. Isn’t that so cool? Glaciers are more important than we thought they were. Now let me tell you about basins. Since plucking pulls rocks out of the ground, sometimes the plucking pulls big boulders creating basins. Sometimes basins create lakes or ponds. Cool right?
V-Shaped Valley
So there is all you should know on how glaciers move and the different landforms they create. Hope you learned all you wanted to! Let’s go meet up with Julia and Aliyah!
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Works Cited “All About Glaciers.” National Snow and Ice Data Center. N.p., n.d. Web. 14 Jan. 2016. <https://nsidc.org/cryosphere/ glaciers>. George, Michael. Glaciers. Minnesota: n.p., 1991. Print. “Glacial landforms.” Bitesize. N.p., n.d. Web. 1 Mar. 2016. <http://www.bbc.co.uk/education/guides/zftycdm/revision/ 2>. “Glacier Facts.” KIDSKONNECT. N.p., n.d. Web. 1 Mar. 2016. <https://kidskonnect.com/science/glaciers/>. “Glacier Facts for Kids.” Science Kids. N.p., n.d. Web. 1 Mar. 2016. <http://www.sciencekids.co.nz/sciencefacts/earth/ glaciers.html>. Hand, Carol. The Creation of Glaciers. New York: n.p., 2010. Print. Hinshaw, Dorthy. Shaping the Earth. New York: Houghton, 2000. Print. “How Glaciers Form and Flow.” http://www.geography-site.co.uk/pages/physical/glaciers/origin.html. N.p., n.d. Web. 14 Jan. 2016. “https://www.polartrec.com/expeditions/ocean-atmosphere-sea-ice-and-snowpack-interactions/journals/2013-09-05.” PolarTREC. N.p., n.d. Web. 1 Mar. 2016. <https://www.polartrec.com/expeditions/ocean-atmosphere-sea-iceand-snowpack-interactions/journals/2013-09-05>. Nadeau, Isaac. Glaciers. New York: Rosen, 2006. Print. Sepehri, Sandy. Glaciers. N.p.: Rourke, 2008. Print. Simon, Seymour. Icebergs and Glaciers. New York: Willam Morrow, 1987. Print. “Untitled Document.” Deserts and Glaciers. N.p., n.d. Web. 4 Mar. 2016. <http://www.indiana.edu/~g103/G103old/ Week8/week8.html>. Walker, Sally M. Glaciers Ice on the Move. N.p.: n.p., 1990. Print. Webster, Chirstine. Glaciers. New York: Weigl, 2006. Print. Webster, Chistine. Glaciers. New York: Weigl, 2011. Print. “What is a Glacier?” Youtube. N.p., n.d. Web. 4 Mar. 2016. <https://www.youtube.com/watch?v=6YMJBNpwsNQ>.
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