Download topic 4 – the moving crust

TOPIC 4 – THE MOVING CRUST
1. What are the five layers of the earth? p. 382 Give 2 key
pts. for each.
1. Crust – 5-60km deep, what we live on, plants, oil, gas
2. Upper Mantle – 1000 degrees C, solid, made of rock,
670km wide
3. Lower Mantle – 4000 degrees C, consistency of taffy,
2885km wide, can flow very slowly
4. Outer Core – 5500 degrees C, 2270km wide, iron and
nickel composition, LIQUID
5. Inner Core – 6000 degrees C, 1216km to center, high
pressure, SOLID
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
- Scientist that studied fossils of plants and animals on
different continents.
- He wondered about the fit of the continents and the
locations of the fossils he found.
-Came up with the theory of continental drift – once the
continents were joined, then they slowly moved apart to
their current locations.
4. Please list the evidence Wegener used to help support
his theory. p. 384
- Fossils from plants and animals
- Interlocking shapes of the continents
- Rocks (ex. Mountain range in North America and Britain
were the same type and age)
- Climatic changes (glaciers were once in now warm regions,
coal deposits)
5. What does SONAR stands for? When is it used? p. 386
Sound Navigation and Ranging – uses sound wave
technology to determine the depth of the ocean
floor/features by measuring how long it takes the sound
waves to bounce back
6. When scientists used sonar, what did they discover
about the oceans?
- They found mountain ranges, ridges, and trenches
- Mid-Atlantic Ridge
7. What is the Mid-Atlantic Ridge? p. 388
- A mountain ridge that stretches from North to South in the
Atlantic Ocean between North America and Europe/Africa.
- Evidence of magnetic reversals and sea-floor spreading
8. What is the theory about the sea floor spreading? What
is some evidence of sea floor spreading? P.388
- Sea-floor spreading is the process in which the ocean floor
at the Mid-Atlantic ridge slowly increases in size over time
due to new igneous rock being formed along a fault
- Evidence: magnetic reversals, rock samples showing
younger rock at the ridge and older rock toward the
continents
9. Define diverging plates – two plates that are pulling
apart
Converging plates – two plates that are pushing together
10. What is the Theory of Plate Tectonics? P.390
- The theory that Earth’s crust is broken up into pieces
called plates. These plates are always moving on Earth’s
mantle.
11. Who is Tuzo Wilson? P.390
- A Canadian scientist that contributed to the theory of
plate tectonics by suggesting that plates could also slide
past each other.
12. What are Convection Currents? What do they cause?
P.392
- The flow resulting from the rise of warmer materials and
the sinking of cooler materials
- They cause the Earth’s tectonic plates to move.
13. When does a subduction zone occur?
- When two plates collide or converge, one plate (the more
dense plate) gets shoved under the other plate, creating a
subduction zone
14. Could convection currents cause the Atlantic Ocean to
widen?
- Yes; the convection currents in the mantle may be causing
the Atlantic Ocean to widen at the Mid-Atlantic Ridge
(diverging ocean plates)
15. Why is the theory of plate tectonics a unifying theory
to explain volcanoes and earthquakes? P.393
- It is a single theory that explains different natural events
and landforms; its our best explanation for earthquakes,
volcanoes, and mountain formation.
16. 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.
Continental Plate + Continental Plate = mountains
Continental Plate + Oceanic Plate = volcanoes and mountain
Oceanic Plate + Oceanic Plate = island arcs and volcanoes
Topic 4 Review – p. 394 #1, 2, 4, 5, 6