Types of Glaciers

I never realised there was so many types of Glaciers, I was naive to think that ice was just ice but the only difference was it's geography. However when you learn that Glaciers cover around 10% of the world's land surface, which means that every continent in the world has a Glacier, and they contain between 70-80% of the worlds fresh water supplies it doesn't seem so surprising.
I have used information from mainly http://www.nsidc.org/ and the http://www.geography-site.co.uk/ to try and condense the vast amount of information there is to fairly simple terms. These will allow students and me alike to understand and remember what type of glaciers there are. I will also be using images as well, which will hopefully show us what they look like.

ICE SHEETS:-
Ice sheets are only found in the Antarctica and Greenland. These sheets are huge Continental masses of glacial ice and snow that are larger than 50000 square kilometres long and up to 4200 meters dense in some areas. As these sheets are so dense, they cover over the whole terrain with the exception of the trans antarctic mountains

Below I have attached illustrates of both Greenland Ice sheet and Antarctica Ice sheet using images from the NASA photo gallery http://www.nasa.gov/



Greenland and surrounding Ice Shelves



Antarctica and its Ice Shelves

 



ICE SHELVES:-
Ice shelves occur when Ice sheets past the land surface and further extend out over the sea and float on the water. These Ice shelves surround most of the antarctic continent, which can be shown in the above image of Antarctica. It is at this area of the Glacier where calving can take place, calving is where ice breaks off at the end of a Glacier. At the Ice Shelves, the sea weakens the Glacier and can cause massive bits of Ice to break off, fell into the ocean and cause Icebergs.

ICE CAPS:-
Ice caps are smaller versions of Ice sheets, covering areas that are smaller than 50000 square kilometres. They are more commonly formed in polar and sub-polar regions that are relatively flat and high altitude. Similar to Ice sheets, Ice caps will cover the land completely but at certain parts of the year some bedrock can be seen. Below is an image of Vatnajokull Glacier, which is Iceland's biggest Glacier and the second biggest in Europe. Underneath this 8100 square kilometre Ice cap Glacier is seven hidden volcanoes, which most are active.

Vatnajokull Glacier, Iceland
http://iceland.vefur.is/iceland_nature/glaciers_in_iceland/vatnajokull.htm

ICE FIELDS:-
Ice fields are similar to Ice caps, however ice fields are effected by the topography of the land below. An Ice field may span over many mountain peaks or even a mountain range. Below is an image of Kalstenius Ice field, located on Ellesmere Island, Canada,  The Ice field produces multiple glaciers that flow into a larger valley glacier. (Royal Canadian Air Force photograph at the World Data Center for Glaciology, Boulder)

Kalstenius Icefield,

VALLEY GLACIERS
Last but not least is Valley Glaciers. These glaciers originate from Ice fields or Ice caps that spill downhill. As you can see in the above picture of the Ice field, Valley glaciers look 'much like giant tongues'  (http://www.nsidc.org/) that usually flow down existing steep V- shape valleys that have been previously eroded from rivers etc. The sheer pressure of these glaciers cause the V-shape valleys to erode and enlarge into flat bottomed U-shape valleys. These valleys are a common sight around the world today from past Glaciation periods. Valley Glaciers can be very long and flow far enough to reach the sea, this is then known as a Tidewater Glacier. Tidewater Glaciers are responsible for calving small icebergs that are not as big as Icebergs from an Ice Shelves but can still cause problems.

Below is a Picture that I took of Franz Joseph Glacier in New Zealand, that hopefully illustrates a Valley Glacier being constraint by steep Valley walls. Also from the http://www.nsidc.org/ gallery is a image of a tidewater Glacier.








Lamplugh Glacier, Alaska
Tidewater Glacier, that shows pieces of Ice debris in the Water
http://www.nsidc.org/



Franz Joseph


There are many other types of Glaciers which can be found on http://www.nsidc.org/ and http://www.geography-site.co.uk/ however I felt that these were the most common and more important. Also this post would be a mile long if I added all types of Glaciers.

Task for Students

Each Student would be assigned a different type of Glacier, as homework or during lesson time they would research the particular glacier. They would then present the Glacier type to the class. This will encourage self learning as well as allowing students a chance to present in front of their classmates

The Theory behind Glaciers

As a framework for researching Glaciers, I am going to use a tool that my teachers used during my education. It was very imaginatively named the 5W's, I felt that it was very beneficial for me in both learning and remembering topics. It allowed me to have the same framework for every topic covered and all I had to remember was the 5 W questions.

1. What is it?
2. Where is it/ where did it occur?
3. When did it happen?
4. Why did it happen?
5. Who did it affect?

I know that some of the answers to the questions will over lap but the questions can be altered slightly to the specific topic that is being covered.

What is a Glacier?

Glaciers occur after many years of fallen snow in the same location, each new layer of snow compresses down on the previous layer to form large ice masses. Due to gravity and the sheer mass of these glaciers they flow like very slow rivers which cause changes in landscapes,which will be discussed later in another post. Also glaciers can vary in size, from relatively small glaciers to glaciers that are around hundred kilometres long.

Where do Glaciers occur?

As discussed in the previous post, using the map from the National Snow and Ice Date Center as a reference we discovered where Glaciers are distributed throughout the world. The locations that were highlighted support the theory of what conditions are needed for Glaciers to develop.                                  

For Glaciers to occur there needs to be a high snowfall in the winter and cool temperatures during the summer. This allows the snow to settle on the ground for the compression to take place over many years. The cool temperatures mean that the snowfall will neither melt, evaporate or allow 'calving' to take place (this will be explained in another section of my blog).

For the growth of Glaciers the amount of precipitation is very important. Even where the temperatures in an area may be very low throughout the year, if the area also has low precipitation levels the growth of the Glacier will be slow.


The next installment will look at the types of Glaciers and why Glaciers are around ...



World Map of Glacier and Ice Distribution

I wanted to add a map showing glaciers and ice distribution across the globe.
This map was found on the National Snow and Ice Data Center http://www.nsidc.org/.

I think that a lot of people and children, me included, have their learning and understanding on topics greatly increased using visual aids. Knowing where glaciers are in the world as well as what they look like will help them to grasp the theoretical concepts quicker (hopefully).

This map allows the viewer to understand that glaciers are massive landforms that cover a large areas of our earth surface. Presently glaciers and ice are situated on high altitudes such as the Alps, Himalayas and the Andes mountain ranges as well as predominately being higher than 60 degrees north of the equator and lower than 60 degrees south of the equator.