Download Deepest Place on Earth film worksheet

How the Earth Was Made:
Deepest Place on Earth
Name ______________________________
Period ______
Loc # _____
1. In 1872, the ____________________________________ set out to map the ocean floor.
2. What process did the crew of the HMS Challenger use to measure the depths of the ocean
floor?
3. At 200 miles off the coast of Guam, how far down did the weight strike bottom?
4. In the 1940’s, SONAR was perfected to detect ___________________________ and has since
been used to map the ocean floor.
5. How does SONAR work?
6. In 1951, a British Navy research ship returned to the deep hole found by the Challenger
expedition and discovered a massive ____________________, which is ________ times deeper
than the Empire State Building is high, and is _____________ miles long.
7. What happens to the sea floor at the southern end?
8. What did they name this area and why?
9. In 1960, the _____________________ , a submersible capable of withstanding crushing
pressures, travelled to the bottom of the trench. They reached a depth of __________________
feet, nearly ________ miles below the surface.
10. In the 1950’s and 1960’s, geologists compiled _____________ data from all of the world’s
oceans.
11. This data revealed a _________________ mile long chain of mountain ranges that ring the
globe, to make the largest geological feature on Earth.
12. During the Cold War, the U.S. built a vast network of underground ____________________
to detect __________________________ testing around the world. These instruments also
detected____________________________ which were primarily clustered around the ocean’s
__________________ and _____________________.
13. Also, during the Cold War, the US Navy developed a new technique, a tool called MAD, a
magnetic anomaly detector, which could pinpoint steel hulls (Soviet ______________________)
lurking in the deep. What else did they find on the ocean floor on either sides of the ridge?
14. In 1977, scientists discovered __________________________ vents, which confirmed that
__________________ is continually creating new crust at the ocean ridges.
15. If the new crust is being formed at the ocean ridges, why isn’t the Earth expanding?
16. Geologists believe that the Marianas Trench formed the volcanic island chain, the Mariana
Islands (which mirrors the trench's exact shape), via a process called ______________________.
17. Usually, subduction zones cause violent earthquakes and catastrophic tsunamis. Why hasn’t
the Marianas Trench caused a devastating earthquake since records began in the 17th century?
18. How fast is the Marianas Trench devouring the crust?
19. Why is the Marianas Trench the deepest trench on Earth?
20. People used to think that maybe the magma would push the plates apart, but that idea is
largely discounted now. What is the latest theory on how the plates move?
21. The plates that are moving fastest on the Earth are the ones that have all the _____________.
22. The _________________________ plate is the fastest moving of the nine major plates on the
planet, because it is surrounded by dozens of destructive trenches like the Marianas. They are
consuming the ocean crust ______________________ than the ocean ridge can produce it.
23. Over millions of years, the ______________________ Plate will shrink until, sometime in
the distant future, the largest ocean on Earth will disappear. __________________________will
crash into the United States, reshaping our planet.