2. Rocks far from the mid-ocean ridge are younger.

3. Sediments are thinner at the ridge.

4. Rocks at the ocean floor are younger than those at the continents.

5. Most basalt magmas contain abundant molten iron.

6. SONAR means Sound Navigation and Radio Ranging.

7. DURING THE 1960’s Harry Hess and Robert Dietz suggested an explanation for the movement of the continents called Seafloor Spreading Theory.

8. Alfred Wegener proposed the Continental Drift Theory.

9. Pangaea means all about earth.

10. Scientists found Glossopteris in India, Antarctica, Australia, and Madagascar.

11. Alfred Wegener examines the location of tiny rocks and the direction of grooves formed by large glaciers scraping across southern areas of Africa, South America, Australia, Antarctica, and India. He concludes that if all these places were fitted together, they would form a continuous ice sheet expanding outward in all directions.

12. Radars and sonars were used to observe the geological processes happening in the Mid-Atlantic Ridge.

13. Alfred Wegener observes that a South American mountain range in Argentina lines up with an ancient African mountain range in South Africa when the two continents are placed together.

14. The reversal in magnetic stripes pattern in ocean floor provide evidence for the scientists to prove the change in Earth’s magnetic polarity.

15. The coastlines of the continents appear to fit together like the piece of a puzzle. If you will look on a world map, you will notice that Africa and South America seem to fit together as if they were once joined.

16. Alfred Wegener is a German scientist who hypothesized that the Earth was once made up of single large landmass called Pangaea. Which of the following theories did Wegener propose?

17. If you were a cartographer, what will give you an idea that the continents were once joined?

18. Which observation was Not instrumental in formulating the hypothesis of seafloor spreading?

19. As a new seafloor is formed at the mid- ocean ridge, the old seafloor farthest from the ridge is destroyed. Which of the stated processes describes how the oceanic crust plunges into the Earth and destroyed at the mantle?

20. Who were the two scientists who proposed the theory of seafloor spreading in the early 1960s?

21. The older seafloor sinks, the weight of the uplifted ridge pushes the oceanic crust toward the trench at the subduction zone. This process is called _____.

22. It involves in the tectonic plate where the weight of the subducting plates pulls the trailing slab into the subduction zone.

23. What is the correct sequence of the process of the convection current?

1. hot, less dense rising material spreads out as it reaches the upper mantle causing forces.

2. The hot magma flows out of the mantle and cools down to form new ocean crust.

3 The forces lift and split the lithosphere at divergent plate boundaries.

4. The downward movement of the convection current occurs along a convergent boundary where the sinking force pulls the tectonic plate downward.

24. The following demonstrate factors that cause the formation of the a current.

10. What demonstrates cyclic motion?