Question

earth science: national geographic - colliding continents video notes

1. list the 7 continents.
2. 4.6 billion years ago, the earth was created from what?
3. as the newly - formed planets orbit the sun, they ____ and __ created the __. one collision with the planet ____
4. the energy from the collision makes the earth incredibly ____. it is a massive __ ball of boiling ____ on the surface of the earth.
5. the heaviest elements, including ____ and __ sink in the early molten earth to form the ____.
6. the lighter elements, including ____ and ____ rise towards the surface and erupt in volcanoes as molten rock.
7. as the earth cooled, molten rock solidified to form ____, but constant bombardment by asteroids ____ it.
8. most scientists believe that the water that formed our oceans came from many, many ______ which contained water.
9. how old was earth believed to be when the first early, relatively stable land masses formed? ______ years old.
10. what type of buoyant rock appeared on the earth’s surface? ______
11. what continent is believed to be the site of the earliest giant continental landmass on earth? ______
12. what type of rock formed the first continents? ______
13. scientists look for durable crystals of ______ in rock samples to date their age.
14. as radioactive uranium decays it turns into what stable element? ______
15. what is a craton? ______
16. why is granite less dense than other rock in earth’s mantle? ______
17. ______ are thought to have helped speed up the breakdown of rock as it emerged at earth’s crust.
18. the ‘giant jigsaw puzzle’ of interlocking pieces that make up earth’s crust are called what? ______
19. the tectonic plates “float” on what layer of earth? ______
20. evidence for the theory of continental drift was first proposed in 1912 by what german scientist? ______

when wegener first proposed his theory of continental drift, why did the scientific community reject his ideas?
much of the heat at the core of earth is left over from ____ and __ during its __ days. the rest comes from ____ of heavy elements in the core.

Explanation:

1. The seven continents are Africa, Antarctica, Asia, Australia/Oceania, Europe, North America, and South America.
2. The Earth formed from the solar nebula.
3. New - formed planets orbiting the Sun collided, creating heat and energy.
4. Collisions made the Earth hot. One collision with a planet (Theia) is notable.
5. Heavy elements like iron and nickel sank to form the core.
6. Lighter elements like silicon and oxygen rose to form the crust.
7. Molten rock solidified to form igneous rock.
8. Water in the oceans likely came from comets and asteroids.
9. The first stable land masses formed about 3.2 billion years ago.
10. Granite is a buoyant rock that appeared on the Earth's surface.
11. It is thought that Africa was the site of the earliest giant continental land - mass.
12. Granite formed the first continents.
13. Scientists look for zircon crystals in rock samples to date them.
14. Uranium decays into lead.
15. A craton is a stable part of the Earth's continental crust.
16. Granite is less dense because it contains lighter minerals.
17. Weathering and erosion helped break down rock at the crust.
18. The interlocking pieces of the Earth's crust are called tectonic plates.
19. Tectonic plates "float" on the asthenosphere.
20. The theory of continental drift was proposed by Alfred Wegener in 1912. The scientific community rejected his ideas initially because he could not explain the mechanism driving the drift.
21. Heat at the Earth's core is left over from the planet's formation and radioactive decay of heavy elements in the core.

Answer:

1. Africa, Antarctica, Asia, Australia/Oceania, Europe, North America, South America
2. The solar nebula
3. Collided; heat; energy
4. Hot
5. Iron; nickel; core
6. Silicon; oxygen; crust
7. Igneous rock
8. Comets; asteroids
9. 3.2 billion
10. Granite
11. Africa
12. Granite
13. Zircon
14. Lead
15. A stable part of the Earth's continental crust
16. It contains lighter minerals
17. Weathering and erosion
18. Tectonic plates
19. Asthenosphere
20. Alfred Wegener; He could not explain the mechanism driving the drift
21. The planet's formation; radioactive decay