Plate Tectonics

Plate tectonics is the theory of the plates on the surface of the Earth moving. This theory was developed in the 1960's and explained many previously unexplained geological phenomenon such as mountain ranges, earthquakes, and volcanoes. There is also a theory for the cause of the movement. It states that this movement is caused by the convection zones inside the Earth's convection zone. The first animation shows the original supercontinent called Pangea. This supercontinent was formed about 225 million years ago. Since then it has broken apart and moved all the way to where they are located today due to plate tectonics. This may seem like a long way for the continents to move, especially because they only move about 2 centimeters per year. This is about the speed at which your fingernails grow. However, as you can see in the second animation, even though the continents are moving at this slow speed they will still one day long from now collide again. This collision will form another supercontinent known as Pagea Ultima. Scientist have calculated and theorized that this continental collide within the next 250 million years.

Sources:

http://science.nasa.gov/science-news/science-at-nasa/2000/ast06oct_1/

http://www.divediscover.whoi.edu/tectonics/index.html

http://www.enchantedlearning.com/subjects/astronomy/planets/earth/Continents.shtml

http://www.cotf.edu/ete/modules/msese/earthsysflr/plates1.html

Mars
Mars is the fourth planet from the Sun and is about 142 miles from the Sun. Its diameter is about 2,960 km in diameter. Mars was named after the Roman god of war. This is because of its red color which is due to its soil which is composed of iron. Mars soil is also composed of basalt and its core consists of iron and some sulfur. Mars exemplifies the accretion theory because of its solid, rocky composition. The accretion theory says that Mars was composed of small pieces of rocks and other things found in the solar system known as planetesimals. The accretion theory's explanation for the relatively small size of Mars is that only a small planet was able to form before the rapidly growing Jupiter pulled all of the planetesimals away from Mars. This theory provides a sufficient explanation about the forming of the planets including Mars.
http://www.scribd.com/ioana_cn/d/55912234/26-The-Accretion-Theory#page=304
http://www.nasa.gov/audience/forstudents/5-8/features/what-is-mars-58.html