Composition of the Earth
It may seem like the Earth is made up of one big solid rock, but it's really made up of a number of parts. Some of them constantly moving! You can think of the Earth as being made up of a number of layers, sort of like an onion. These layers get more and more dense the closer to the center of the earth you get. See the picture below to see the four main layers of the earth: the crust, mantle, outer core, and inner core. Crust The crust is the thin outer later of the Earth where we live. Well, it looks thin on the picture and it is thin relative to the other layers, but don't worry, we're not going to fall through by accident anytime soon. The crust varies from around 5km thick (in the ocean floor) to around 70km thick (on land where we live called the continental crust). The continental crust is made up of rocks that consist primarily of silica and alumina called the "sial". Mantle The next layer of the Earth is called the mantle. The mantle is much thicker than the crust at almost 3000km deep. It's made up of slightly different silicate rocks with more magnesium and iron. Tectonic plates The tectonic plates are a combination of the crust and the outer mantle, also called the lithosphere. These plates move very slowly, around a couple of inches a year. Where the plates touch each other is called a fault. When the plates move and the boundaries bump up against each other it can cause an earthquake. Outer Core The Earth's outer core is made up of iron and nickel and is very hot (4400 to 5000+ degrees C). This is so hot that the iron and nickel metals are liquid! The outer core is very important to earth as it creates something called a magnetic field. The magnetic field the outer core creates goes way out in to space and makes a protective barrier around the earth that shields us from the sun's damaging solar wind. Inner Core The Earth's inner core is made up of iron and nickel, just like the outer core, however, the inner core is different. The inner core is so deep within the earth that it's under immense pressure. So much pressure that, even though it is so hot, it is solid. The inner core is the hottest part of the Earth, and, at over 5000 degrees C, is about as hot as the surface of the sun. "Science for Kids: Composition of the Earth." Ducksters. Technological Solutions, Inc. (TSI), Mar. 2014. Web. 8 Mar. 2014. <http://www.ducksters.com/science/composition_of_the_earth.php>. Layers of the Earth SongThese are codes you will need for the link phschools.com. codes cpj-0003 vocabulary; cfd-1012 convection currents; cfd-1014 seafloor spreading; cfd-1015 continental drift; cpa-0003 quiz
Earth's Interior & Plate Tectonics |
Watch the animation of the continents moving apart. This shows what it looked like as Pangaea and then today.
To reconstruct the supercontinent, Pangaea, click on the image to do this on an interactive website.
Plate Tectonics
A Land in Motion Although we think of the land on Earth as being fixed and stable, it turns out that it is constantly moving. This movement is way too slow for us to notice, however, because it only moves between one to 6 inches per year. It takes millions of years for the land to move a significant amount. The Lithosphere The part of the land that is moving is the Earth's surface called the lithosphere. The lithosphere is made up of the Earth's crust and a part of the upper mantle. The lithosphere moves in big chunks of land called tectonic plates. Some of these plates are huge and cover entire continents. Major and Minor Tectonic Plates Most of the Earth is covered by seven major plates and another eight or so minor plates. The seven major plates include the African, Antarctic, Eurasian, North American, South American, India-Australian, and the Pacific plates. Some of the minor plates include the Arabian, Caribbean, Nazca, and Scotia plates. Continents and Oceans Tectonic plates are around 62 miles thick. There are two main types of tectonic plates: oceanic and continental.
Plate Boundaries The movement of tectonic plates is most evident at the boundaries between the plates. There are three main types of boundaries:
Interesting Facts about Plate Tectonics
"Earth Science for Kids: Plate Tectonics." Ducksters. Technological Solutions, Inc. (TSI), Mar. 2014. Web. 8 Mar. 2014. <http://www.ducksters.com/science/earth_science/plate_tectonics.php>. |