Review – Forces inside the Earth
1. Describe weathering, erosion, and deposition (from 6th grade).
Weathering – Breaking down of rocks into sediment through any form of weather (rain, sleet, wind, etc)
Erosion – When the sediment is carried away
Deposition – When the sediment is dropped off
2. Who proposed the Theory of Continental Drift? What are the 4 pieces of evidence supporting this
theory?
Alfred Wegener – puzzle pieces match up, mountains line up, fossil evidence on separate continents, coal deposits
in places where they should not be
3. What was the name given to the land that describes all of the continents pieced together? Pangaea
4. Describe where each of the following is located: mid-ocean ridge, rift valley, and trench.
Mid-Ocean Ridge – underwater mountains in the middle of the ocean
Rift –Valley – an opening where two plates are being pulled apart and lava comes through
Trench – a v-shaped valley where oceanic crust is subducted (pushed down)
5. How do the above terms relate to Ocean Floor Spreading?
Lava comes up through the rift valley and pushes the old ocean floor aside at the mid-ocean ridge, while
old ocean floor is subducted at the trench and destroyed (melted)
6. What is the theory of Plate Tectonics?
The theory that combines ocean floor spreading and continental drift and discusses the origin of earthquakes,
mountains, volcanoes…
7. What is the definition of Lithosphere? Name at least two of the 7 major Lithospheric plates.
The topmost solid part of the Earth that is divided into pieces called tectonic plates. African, Eurasian,
Indo-Australian, North American, South American, African, Pacific
8. Name and describe the three types of plate boundaries. What landform or activity does each create?
Divergent – when plates move apart at the Mid-Ocean Ridge
Convergent – when plates come together = Volcanic Mountains, Island Arcs, Mountains
Transform – when plates slide past each other = Earthquakes
9. The rocks on the ocean floor near the Mid-Ocean Ridge are (younger or older) than rocks closest to the
continents. Why??
Younger…New lava is coming through the Rift Valley and pushing the old ocean floor aside. The lava will
harden and become new ocean floor. The oldest floor keeps getting pushed further and further out.
10. What happens when an oceanic plate and a continental plate collide?
Oceanic plate subducts at a trench and creates volcanic mountains (ex: Andes Mountains in South
America)
11. What happens when two continental plates collide?
Both uplift to form mountains (ex: Himalaya Mountains)
12. What happens when two oceanic plates collide?
One oceanic subducts at a trench forming island arcs (ex: Aleutian Islands)
13. Which is more dense – a continental plate or an oceanic plate?
An oceanic plate
14. Where is the Ring of Fire and why was it given this name?
The ring of fire is an area of high volcanic and earthquake activity that surrounds the Pacific Plate. The
ring of fire is caused by the Pacific plate grinding against the continental plates of North and South
America, and Asia.
15. What causes Earthquakes?
Earthquakes are caused by faulting, a sudden lateral or vertical movement of rock along a rupture (break)
surface.
16. What do Topographic Maps illustrate?
They illustrate the different features on land. Topographic maps determine where the land is flat, has
mountains or valleys.
17. What does it mean when contour lines are close together? Far apart?
Close together – slope is steep like on a cliff or a canyon
Far apart – slope is gentle/gradual or flat