Friday, October 2nd, 2009...1:40 PM
This week in science we learned about plate tectonics and did a few activites.
In 1910 Alfred Wegener came up with the theory of Continental Drift. But it wasn’t until the 1960′s that the idea was taken seriously and renamed Plate Tectonics. The surface of the Earth is divided into approximately six large ‘plates’, plus a few smaller ones. Under the World’s oceans, these plates are composed of the same material as the fluid mantle, but are supercooled into solid rock, and are typically around 6 to 10 miles thick.
Where the plates meet we have different kinds of boundaries. Our activity, below, showed us the effects of each of the different kinds of boundaries. I’ve seen this procedure done with carpet pieces and foam also.
This activity called for us to roll out a bit of modeling clay to form a road. We then lay it on two pieces of wood that represented two plate tectonics.
This photo shows an example of a divergent boundary. The two plates are moving away from each other causing a dip in our road. This most often happens near ocean ridges.
The next type of plate tectonic we learned about was called a convergent boundary. This happens when two of the plates move toward each other. One plate is ultimately forced down below the other.
When this happens near land we see the earth rise above the meeting place, much like our road in the picture above, and mountains are formed. This type of boundary can cause volcanoes to form and as the two plates rub against each other small and large earthquakes can happen.
Another plate boundary is called a transformation boundary. This occurs when you have two plates that slide against each other in a sideways motion. In this particular boundary neither plate is added to or destroyed. But it does result in massive amounts of energy building up. Sometimes this energy is released in the form of earthquakes.
We like movies, so we enjoyed watching the following videos to reinforce the ideas:
Volcanoes and Plate Tectonics by HowStuffWorks
Plate Tectonics on Youtube
And these web sites were an amazing help: