6th ch 8 science

Question Answer
Seafloor spreading Magma pushes up through Earth's crust. As the magma cools, it forms new crust. more magma comes up and pushes the newly formed crest any Old crust aside.
Pangaea Wegener thought that about 225 million years ago the continents were joined in one large continent. Also means "all earth"
Plate tectonics The earth's lithosphere is broken into about 20 moving plates . The continents and ocean floor make up the surfaces of these moving plates
Continental drift Continents drifted apart in the past and continue to do so
Seismograph Scientists use this to listen for trimmers this instrument instrument records ground movement
Sliding or fracture boundaries To plate sliding past each other
Spreading boundaries These plates are moving away from each other
colliding boundaries These plates are colliding with each other
earth's core The innermost layer of the earth. Much denser or compacted than the mantle
Earth's crust The outermost solid layer of Earth , the part of the earth we live on
Earth mantle the layer of Earth just below the crest . This layer contains most of the earth mass
In early 1900, Alfred Wegener introduced the theory of the continental drift. One part of history included Pangaea . Explain what Pangia is and why it is part of Wegener's theory. Wegener thought that about 225 million years ago the continents were joined in one large continent called Pangaea. Wagener suggested that long ago Pangaea broke apart to what they are now
What is seafloor spreading and how to support the theory of continental drift? When magma pushes through Earth's crust , as the magma cools, it warms new crust. More magma comes up and pushes the newly formed crest and the Old crust aside. This supports the theory of continental drift from the data scientist collected long ago.
Describe how the theory of plate tectonics explains why most earthquakes occur near plate boundaries. Earth is broken into about 20 moving plates. The continents and the ocean for make up surfaces of these moving plates . Most earthquakes occur near these plate boundaries where two plates meet and move by either spreading, fracture or colliding boundaries