1. THE USE OF SONAR, AND THE THEORY OF SEAFLOOR SPREADING. By: Rishon Pryce, Kaylee French Period – 6 09/21/15

2. SONAR. The definition of sonar is: Sonar (an acronym for sound navigation is a way to use sound to navigate, communicate or detect objects on or under the surface of the water, such as vessels.

3. There are two types of sonar, one being Active Sonar which emits pulses, or signal of sound that goes down and bounces off objects and returns such as an echo. The depth can be determined be the time is takes for the signal or pulse to return to the ship.

4. Sonar became an important tool to oceanography when people found a way to use it to see the ocean floor. When the signal came back it painted a picture in a way that showed the ocean floor and what it looked like such as the different depths. The use of sonar showed how much deeper the ocean was compared to what people thought, this really opened peoples eyes to the new things that lie within the oceans depths.

5. Seafloor spreading. Seafloor spreading- is a process that occurs at mid-ocean ridges, where new oceanic crust is formed through volcanic activity and then gradually moves away from the ridge. Seafloor spreading helps explain continental drift in the theory of plate tectonics.

6. Seafloor spreading and other tectonic activity processes are the result of mantle convection. The mantle melts and is pushed up through the ocean floor. The crack where the magma flows out is where the plates are being pulled apart. This makes what is known as the mid ocean range. The mid ocean range is a range on mountains created be the hot magma that flows from within earths crust. The theory of seafloor spreading also helps to explain plate tectonics and how everyone lives on large moving mass of land.

7. Sea floor spreading occurs in the Atlantic ocean between north America, and Africa. On the opposite side of the earth, the sea floor is doing the opposite of spreading and is being pulled back into the earth. This process is called subduction, scientist suggest that the continents will join back together in the future.

8. The earth will always stays the same size, just because the ocean floor is growing does not mean that the earth is growing in size. Many people can not understand this and it is also the reason that the theory of seafloor spreading is still a theory. There is evidence of this though, in the pacific ocean, the earths crust is being pulled back in to earth.

9. Credits http://education.nationalgeographic.com/encyclopedia/s eafloor-spreading/ http://education.nationalgeographic.com/encyclopedia/s eafloor-spreading/ http://www.bing.com/images/search?q=subduction&view= detailv2&&id=7C4738C624396A4AD5B31B98992C4059F4C3C A7E&selectedIndex=99&ccid=eDqbPQsB&simid=6080532096 07769618&thid=OIP.M783a9b3d0b014078e53dde978483cdf co0&ajaxhist=0 http://www.bing.com/images/search?q=subduction&view= detailv2&&id=7C4738C624396A4AD5B31B98992C4059F4C3C A7E&selectedIndex=99&ccid=eDqbPQsB&simid=6080532096 07769618&thid=OIP.M783a9b3d0b014078e53dde978483cdf co0&ajaxhist=0