Download Planet Earth - Topic 4 (ANSWERS)

Unit # 5 - TOPIC 4 – THE MOVING CRUST
1. What are the five layers of the earth? p. 382 Give 2 key pts. for each.
1. Crust: 5 degrees Celsius, ranges from 5-60 km
2. Upper Mantle: 1000 degrees Celsius, 670 km deep, forms (with the crust) part
of the Lithosphere
3. Lower Mantle: 2885km in depth, 4000 degrees Celsius, partly melted
(consistency of taffy)
4. Outer Core: 2270 km in depth, composed of iron and nickel (liquids), 5500
degrees Celsius
5. Inner Core: Solid ball due to pressure, 6000 degrees Celsius, 1216 km in depth
2. Draw a diagram of the earth. Include – Crust, Upper & Lower Mantel, Outer
and Inner Core. p. 382
3. Who is Alfred Wegener? What were some of his ideas? p. 383
A scientist who hypothesized that the continents were once joined together. He
called this super continent PANGAEA. The continents were then separated. He
called this the ‘Theory of Continental Drift’.
4. Please list the evidence Wegener used to help support his theory. p. 384
Biological: plants and animal fossils were found on different continents.
Rocks: they found similarities of rocks on both sides of the Atlantic Ocean
(different mountain ranges contained the same type of rock)
Geological: in order for coal to be formed, it must have a tropical environment.
Coal is found in many places where there is no tropical weather (Ex: Alberta).
Most of the places were thought to be covered by glaciers.
5. What does SONAR stands for? When is it used? p. 386
Sound Navigation and Ranging. It is used to study the surface at the bottom of
the ocean.
6. When scientists used sonar, what did they discover about the oceans?
They discovered that there were mountains on the sea floor. The mountain ranges
were long and very similar to the ranges that existed on land.
7. What is the Mid-Atlantic Ridge? p. 388
It is a mountain range spanning the Atlantic Ocean from North to South. They
found more information on this according to the magnetic field using a
MAGNETOMETER.
19. What is the theory about the sea floor spreading? What is some evidence of
sea floor spreading? P.388
The theory is that the magnetic stripes that ran along the bottom of the ocean
floor were reversed. Evidence of Sea Floor Spreading suggests that the process
of the of the ocean floor slowly increasing size over time because of the
formation of new igneous rock. (The Atlantic Ocean is widening about 2cm every
year)
21. Define diverging plates – plates that pull apart or separate
converging plates – plates that come together
22. What is the Theory of Plate Tectonics? P.390
The earth is made of different plates (sections). These plates are always moving
on the mantle due to convection currents.
23. Who is Tuzo Wilson? P.390
A Canadian scientist who hypothesized that tectonic plates could experience a
third kind of movement: plates that slide past each other.
24. What are Convection Currents? What do they cause? P.392
Convection currents is the flow resulting from the rise of warmer and the sinking
of cooler material. They are moving the earths crust which can cause Volcanoes,
Mountains and islands to form. They can also cause subduction zones.
25. When does a subduction zone occur?
When two plates collide or converge, one is shoved under the other.
27. Could convection currents cause the Atlantic Ocean to widen?
Yes because new rock is forming and is widening the space between the
continents.
28. Why is the theory of plate tectonics a unifying theory to explain volcanoes
and earthquakes? P.393
It explains why we have natural events and landforms. It is our best explanation
for the formation of earthquakes, volcanoes, and mountains,
29. Please sketch and label Figure 5.46 on p. 392-393. Be sure you label all arrows
and letters and get the information from A, B & C.