I would like to dedicate this book to my grade, something that determines whether or not I get to go home.
The most interesting thing I learned in the unit was the different ways our world changes. I thought it was cool that Earth used to be one giant land mass, Pangea. It's mind blowing the Earth is changing so much right below our feet!

Convection currents are differences in density by unequal heating, which causes them to move in circular motions. When hot magma rises and spreads out, the cooler material is pushed down. This is caused by heat from the core and lower mantle, specifically the asthenosphere. This is important to the Plates Tectonics Theory because it explains the movement of the Earth's plates.
The Continental Drift Theory was proposed by a scientist named Alfred Wegener. The theory states 25 million years ago, all of the present day continents used to be one huge continent. Scientists of that time did not support Wegener's theory because he didn't know why the land split. However, Wegener was able to prove his theory with evidence. He proved his theory with fossils of plants such as the Glossopteris and reptiles such as the Mesosaurus, deposits of coal and glaciers, mountain ranges in different continents lining up, and boundaries of every continent fitting together like puzzle pieces. Seed ferns were too big to be carried by wind over the ocean to different continents, and the Messosarus were fresh water reptiles that could not survive swimming across the salty ocean. Coal and glacier deposits were found in areas that could not be formed where the continents are now. The cape mountains lined up with each other as if they were split in half. They were proved to be the same age and rock type. The piece of evidence that finally got people to believe Wegener was boundaries of all of the continents fitting together just like a gigantic puzzle.
The Sea floor Spreading Theory states the ocean floor continuously adds new material to the ocean floor. Molten material rises from the mantle and erupts, which spreads out, pushing older rocks to the sides of the ridge. This theory was brought up by Harry Hess, and he used three pieces of evidence to support his theory. Molten material is new material erupting along the mid ocean ridge. Magnetic stripes make up the ocean floor and lock in place when the poles reverse themselves. This allowed scientists to determine the age of the rocks. The rocks at the center of the mid ocean ridge are younger and the rock farther away are older. This theory is important because it gave the science world more information about the Earth and how it takes care of itself.
The Plate Tectonics Theory explains the formation, movement and subduction of the Earth's plates. These plates collide, pull apart, and grind past each other, which always affects other plates.
The three types of stress are compression, tension, and sheering. Stress is a force that causes the lithosphere to change shape, break, or move. Compression is going towards each other. Tension is going away from each other. Sheering is going past each other.
Convergent boundaries are when two plates move towards each other. This can form mountains, trenches, volcanoes, and islands.
Divergent boundaries are two plates move away from each other. This can form new ocean floor, rift valleys, and underwater volcanoes.
Transform boundaries are when two plates slide past each other in opposite directions. This can form earthquakes and faults.
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I would like to dedicate this book to my grade, something that determines whether or not I get to go home.
The most interesting thing I learned in the unit was the different ways our world changes. I thought it was cool that Earth used to be one giant land mass, Pangea. It's mind blowing the Earth is changing so much right below our feet!

Convection currents are differences in density by unequal heating, which causes them to move in circular motions. When hot magma rises and spreads out, the cooler material is pushed down. This is caused by heat from the core and lower mantle, specifically the asthenosphere. This is important to the Plates Tectonics Theory because it explains the movement of the Earth's plates.
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