Types of Plate Boundaries
Divergent- when two plates are moving apart. Crust is created forming a ridge. Ex. Mid- Atlantic ridge. Convergent- when two plates are moving towards eachother. Crust is either created or destroyed forming a trench or mountain. The two types of convergent boundaries are subduction zone and collisional. Subduction zone- an ocean plates slides under a continental plate and is remelted into the mantle. Ex. Pacific Coast of Naimalayes, India. Explain the theory of Plate tectonics- it is the movement of plates. Plates hold continent or parts of continents and oceans. Plates touch each other and cause earthquakes and volcanic eruptions. Why are most earthquakes and volcanoes located near plate boundaries- they are located near boundaries because the plates are colliding next next to eachother making mountains, and they can shake and make volcanic eruptions. 1915, german scientist came up with the theory of Continental drift (Alfred Wegener- 1915) he suggested: 300 million years ago, all of the Earth’s land masses collided to form one big supercontinent called Pangaea. Pan-entire, Gaia- Earth in greek so Pangaea is entire earth. Then 200 million years ago, this masses began to break apart and drift to the spots they are today:the seven continents. (Paleozoic and Mesozoic) 1- Jigsaw fit (most obvious)- continental shelf
2- Fossils from the same land dinosaurs appear on different contients(they cant swim) 3- Evidence of glacial activity and ice sheets on continents that are hot today. (must have at one time been closer to the cold south pole.) 4- Mountains of similar age and structure on both sides of the atlantic ocean.
Tropic of cancer- Parrell of latitude at 23.5 degrees north of the equator. Northermost point at which the sun can appear directly overhead at noon. The sun rays strike here one day a year on the summer solstice(on or about june21) Tropic of Capricorn- parrell of latitude at 23.5 degrees of the equator....
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