Research Pgs. PowerPoint Project

Research Pg. 1
A scientific theory is a tested concept supported by experiments, observations and evidence. A law however, is proven and is supported by all scientists.

Research Pg. 2
GPS is the Global Positioning System. It is made up of 24 satellites that circle the Earth at 20,200 km high. Receivers at stations on Earth use the satellite signals to calculated the location of each station. Geoscientists have placed receivers in multiple places on Earth to keep track of the movement of the lithospheric plates. Steel spikes are pounded into the ground which helps the satellites locate the targets. Scientists revisit each target every few months or years. Changes in location can be detected within several millimeters. This technology has only been around about 20 years.
Geoscientists study the magnetism of rocks that make up the sea floor. Matching patterns on either side of the mid-ocean ridge can be explained by new ocean crust forming at the ridge and fading away. Because of the magnetic strip on the ocean floor records the reversals of Earth’s magnetic field, scientists can calculate the average rate of plate movement during any given time.

Research Pg. 3
The Earth’s crust and mantle are the two layers that are in motion. The mantle undergoes thermal convection which is why it is in motion. The core heats up mantle material which causes it to rise. Once it gets to the top it cools and falls back to the bottom and repeats the process. The crust is in motion because this rising mantle material can break a continent apart and force them into different directions.
The Earth’s internal heat includes rotting of radio active elements, the original heat of the formation of Earth. The transfer of heat from Earth’s interior to its surface drives the movement of Earth’s crust and mantle.
Thermal convection is when material at the mantle-core boundary is heated and rises upward and spreads horizontally, cools and sinks back down. Then, this process is repeated.
Thermal convection causes the mantle material to rise up to the surface where the tectonic plates have separated from each other. Then, material sinks back into the Earth where the plates crash into each other. This is how plates are created and destroyed.

Research Pg. 4
The mantle is the layer of Earth directly below the crust. There are many different types of rock within the mantle. The upper part of the mantle (which is cooler that the lower part of the mantle) moves as a stiff block carrying the crust. The upper rigid part of the mantle combined with the crust is called the lithosphere. The lower part of the mantle is very hot and slowly flows like a stiff liquid. This part of the mantle is called the asthenosphere.
The outermost layer of the Earth is called the crust. There are two types of crust. They are called the continental crust and the oceanic crust. The continental crust is what makes up Earth’s continents. It is about 30-50 km thick. The ocean crust is only 5-10 km thick.
The core is mostly iron. The core is so hot that the outer core is molten. The inner core is hot but under great pressure so it stays solid. The outer core is about 2150 km thick and is made up of liquid-iron nickel. It is 3000-6000 degrees Celsius and has a density of 12. On the other hand the inner core is not as thick as the outer core. The inner core is 1230 km thick and consists of solid-iron nickel. It is about 7000 degrees Celsius and has a density of 12.

Research Pg. 5
The three types of plate boundaries are convergent, divergent and transform boundaries. A convergent plate boundary is when two plates move towards each other. Divergent plate boundary is when two plates move away from each other. Transform plate boundaries are when two plates slide past each other in a parallel direction.
A convergent plate boundary is when two plates collide with each other. When they collide one continent has to go under and it will probably create volcanoes and earthquakes. When two oceanic lithospheric plates collide the denser oceanic plate goes under creating a trench. Then when an oceanic plate and a continental plate collide, the oceanic plate goes under and the continent goes on top because the continent is less dense. This creates a volcano.
A divergent plate boundary is a plate boundary that separates two plates from each other. Divergent plate boundaries that occur in the ocean are called mid-ocean ridges. When they separate the magma rise up, harden, and forms new crust.
A transform boundary is when two plate boundaries slide past each other in a parallel direction. These boundaries cause transform faults on land. A transform fault is a long hole in the ground where the plate’s boundaries broke apart.

Research Pg. 6
Over the years scientists have come up with evidence to help support the theory of plate tectonics. One piece of evidence is the fact that many plants and fossils are found on multiple continents. Another piece of evidence is that many continents such as South America and Africa fit together like puzzle pieces.
F.J. Vine and D.H. Matthews are two scientists, who in 1963 proposed the theory of sea-floor spreading. This theory stated that magma would rise up to the crust from the mantle and when it hit the water it would harden and form new crust on the sea floor.
Eduard Suess wanted to solve the question “How do mountain ranges form?” He then had a theory that land bridges use to connect continents. There were a lot of similar fossils on different continents, so he said that they had land bridges and they sunk into the ocean over time. His theory was not correct.
Alfred Wegener hypothesized continental drift. He also came up with the theory of Pangaea and how it was broken into separate continents. Wegener’s hypothesis showed no need for the land bridges Suess had said was there. Wegener thought that material underneath the Earth’s lithosphere is like slow moving fluid that horizontal movement is formed mountains and he was correct.