The+Earth's+Development

 media type="file" key="The Earth's Development.mp3" [|The Earth's Development.mp3] About 4.6 billion years ago, the earth was formed. There were powerful forces that built up the earth's surface such as volcanoes, earthquakes, and faulting, and other forces that shaped (wore down) the earth's surface such as erosion and weathering. These forces created the mountains and other landforms, along with the various soils, climates, and cycles.  As the earth cooled, the planet's surface cooled. To create a mental image, the inside of the earth could be compared to the inside of a soft-boiled egg: the yolk is the earth's core, the runny white is the earth's mantle, and the shell is the earth's thin crust.  ACTIVITY#1-write another "mental image" of how the earth formed in the discussion forum. It has to follow along the lines of this paragraph, but without using the egg example.

Did you know there was once one super-continent called Pangaea? At one time, all of the world land masses were joined - that was the super-continent. RESEARCH Pangaea, think about what it might have looked like in comparison to the way the worlds look like now and how long ago it existed.

When we talk about landforms, we are talking about the crust of the earth. The tectonic plates or pieces of the crust of the earth have been moving around slowly as discussed above. For instance, the Atlantic Ocean is the space between Canada and Europe that has been caused by plates moving apart for millions of years.  The continents have been moving apart at a rate of approximately 2 cm per year. This is called "continental drift". The convention currents under the crust cause these movements. Again, to create a mental image, the earth's crust is like the skin of milk that forms on the top of cooling soup. With the earth, as with the soup, the movement of the liquid underneath causes the slow movement of the layer on top. These tectonic plate movements have a great impact on our planet.

 Tectonic plate movement causes: Volcanoes - melted rock (magma and lava) pushes up through the cracks of the crust and reaches the earth's surface. Earthquakes - two plates slip suddenly along fault lines which causes a forceful movement that may lead to immense damage.  Activities such as volcanoes and earthquakes occur along the edges of plates. There is a high

concentration of tectonic activity around the Pacific Ocean. This area is called the Pacific Ring of Fire.

ACTIVITY#2-find out what countries are part of the Pacific Ring of Fire. List them and hand in.
= =

 Canada experiences a wide range of natural events due to tectonic activity. Some of these include earthquakes, volcanoes, avalanches, and tsunamis. The crust of the earth is constantly changing. Mountains and islands are being built while the land is being broken down by weathering (rain, ice, cold, heat, wind) and worn away by erosion. ====Need evidence that mountains were pushed up from the forces of plate tectonics? You can easily find fossils of ancient fish at the top of some of the tallest mountains in the world! ====

Geologic History <span style="font-family: 'Arial Black',Gadget,sans-serif; font-size: 150%;"> A Video to get you started.... <span style="font-family: 'Arial Black',Gadget,sans-serif; font-size: 150%;"> media type="custom" key="4887633"

<span style="font-family: 'Arial Black',Gadget,sans-serif; font-size: 150%;"> Imagine that it is springtime and you are crossing a frozen lake. As you start out, the ice seems stable and solid, but in fact, it is not. Before you reach the other shore, the ice starts to break up. Large cracks develop, separating the ice into huge plates that are moved by wind and currents in the water below. Some of these ice plates are pulled apart, while others are smashed together forcing one to ride up over the other. Some of the plates drift away to form floating platforms.

<span style="font-family: 'Arial Black',Gadget,sans-serif; font-size: 150%;"> What does this have to do with the study of geology? The earth's structure is similar to a frozen lake. The surface of the earth is a thin layer of moving plates, and below these plates is material that is also in motion. Every year around the world, there are about 30 000 earthquakes that are strong enough to be felt. These earthquakes indicate the movement of parts of the earth's rigid upper layer.

<span style="font-family: 'Arial Black',Gadget,sans-serif; font-size: 150%;"> Seismologists are scientists who study earthquakes. They have discovered that most earthquakes occur only in a few areas. Earthquakes frequently occur where the edges of the earth's plates are moving in relation to each other. Not all seismologists, however, agree on the exact locations of some of the boundaries

<span style="font-family: 'Arial Black',Gadget,sans-serif; font-size: 150%;">PLATE TECTONICS <span style="font-family: 'Arial Black',Gadget,sans-serif; font-size: 150%;"> Watch this Video before you go on....

<span style="font-family: 'Arial Black',Gadget,sans-serif; font-size: 150%;"> media type="custom" key="4887609" <span style="font-family: 'Arial Black',Gadget,sans-serif; font-size: 150%;">If you examine a map of the world, you might notice that the shapes of South America and Africa look like they could fit together. If they were once together, why are they now apart, and what forces could move such large land masses?

<span style="font-family: 'Arial Black',Gadget,sans-serif; font-size: 150%;"> In 1915, Alfr

<span style="font-family: 'Arial Black',Gadget,sans-serif; font-size: 150%;">ed Wegener, a German scientist, said that the only possible answer was continental drift. He suggested that about 300 million years ago all of the earth's land masses, which were in constant motion, collided to form one supercontinent. He called it Pangaea, which means "all land". About 200 million years ago, the supercontinent of Pangaea started to break up. The pieces drifted in different directions to their present positions.

<span style="font-family: 'Arial Black',Gadget,sans-serif; font-size: 150%;"> What proof did Wegener have that the huge continents of the earth could move and that his theory of continental drift was correct? Most scientists disagreed with Wegener because he could not explain what mechanism was powerful enough to move huge continents. It was not until the 1960s that the technology existed to further develop Wegener's theory. In fact, it was a Canadian, J. Tuzo Wilson, who helped to spark new interest in the theory of continental drift. By 1968 a new theory, known as plate tectonics, was developed.

<span style="font-family: 'Arial Black',Gadget,sans-serif; font-size: 150%;"> theory: an explanation based on observation and reasoning. Don't confuse it with having a theory about why someone said something nasty to someone else, or why your Mom always gives you the gears about hanging out with a certain friend. It is something FAR more solid and based in science and reason. A scientific theory can change, but you need rock solid evidence to do so.

<span style="font-family: 'Arial Black',Gadget,sans-serif; font-size: 150%;">tectonics: relating to the internal forces which deform the earth's trust <span style="font-family: 'Arial Black',Gadget,sans-serif; font-size: 150%;"> Plate tectonics is the theory that helps explain most geologic processes. The theory states that the earth's outer shell is made up of about twenty plates. Most of these plates are made up of both a continent and an ocean. They are moving over a weak layer of hot rock, several hundred kilometres below the earth's surface, which flows like slow-moving plastic. No one fully understands the forces that cause the plates to move over this weak layer. It is possible that the unequal distribution of heat within the earth causes convection currents to move the plates.

<span style="font-family: 'Arial Black',Gadget,sans-serif; font-size: 150%;">ACTIVITY#3. Go to www.wikipedia.org and find the article on plate tectonics. Translate it to Simple English and copy and paste it to a doc and save it to Mr M's homework flash drive. Would the first person to do that please post it in the discussion forum. Thank you.

<span style="font-family: 'Arial Black',Gadget,sans-serif; font-size: 150%;">convection: a heated fluid rises and carries heat with it, to be replaced by a cool fluid which in turn is heated and rises, creating a current

<span style="font-family: 'Arial Black',Gadget,sans-serif; font-size: 150%;"> Here is how Wegener tried to prove his theory of continental drift:

<span style="font-family: 'Arial Black',Gadget,sans-serif; font-size: 150%;"> A He saw the jigsaw fit between South America and Africa. <span style="font-family: 'Arial Black',Gadget,sans-serif; font-size: 150%;"> B He found fossils of the same plants and animals on both continents. He felt that they could only exist in both places if the continents were once joined together. <span style="font-family: 'Arial Black',Gadget,sans-serif; font-size: 150%;"> C There are mountains similar in age and structure on both sides of the Atlantic Ocean - the Appalachians in the eastern United States and Canada, and similar mountains in the northern British Isles and Europe. These mountains formed about 300 million years ago when North America collided with Europe and northern Africa. <span style="font-family: 'Arial Black',Gadget,sans-serif; font-size: 150%;"> D Ice sheets covered southern Africa, India, Australia, and South America about 250 million years ago. How could this ice develop in places that are so warm today? The only explanation seemed to be that at one time the continents were located closer to the South Pole.

<span style="font-family: 'Arial Black',Gadget,sans-serif; font-size: 150%;">ACTIVITY #4-a challenge! Summarize how Wegener proved his theory of continental drift. Post it in the discussion forum. I will grade you on how short you can make the summary while still having it make sense!