Test Review

1) What is the Theory of Plate Tectonics?
The Earth’s crust is divided into sections (plates) that float on the mantle and move due to convection currents in the mantle.

2) For Each of the landforms below, draw a diagram and show how it is formed by the movements of tectonic plates.
mountains & deep ocean trenches:.

2) For Each of the landforms below, draw a diagram and show how it is formed by the movements of tectonic plates.
Mid-ocean ridge & rift valley

3) What evidence did scientists use to understand that Earth is broken into plates?
The evidences began with Wegener’s
Theory of Continental Drift. Ultimately,
It is the volcanoes and the origins of
Earthquakes that created a dot-to-dot the really allows us to draw plate boundaries.

4) What is the force that drives the movement of the tectonic plates?
Convection currents in the mantle.

5) Describe the steps in history leading to the development of Plate Tectonic Theory?
• Noted similar fossils on separate continents
• Wegener’s Theory of Continental Drift (early 1900’s)
• Development of Sonar (1940’s)
• Discovery of Mid-Ocean Ridge
• Noted that the seafloor was older further from the center
• Theory of Sea Floor Spreading
• Patterns of Earthquakes & Volcanoes (dot to dot)
• Theory of Plate Tectonics (1960’s)

6) What is the Theory of Continental Drift?
Alfred Wegner stated that at one time, the continents were joined as a single super-continent, which he named
Pangaea. The continents have slowly drifted apart since then.

6, cont’d) What is the Theory of Continental Drift?
• Continents appear to fit together like a jigsaw puzzle.
• Distribution of fossil remains over several continents.
• Similar rock layers on different continents.
• Glacial marks on different continents appear to line when the continents are moved together.

8) Explain Sea Floor Spreading
Sea Floor Spreading is the eruption of volcanoes at the mid-ocean ridge forming new crust and pushing outward from there so that the older crust is found at the edges of the plates. the movement of the sea floor is caused by the convection currents in Earth’s mantle.
Sonar was a key technology that led to the idea of Sea Floor Spreading.

9) Sketch a diagram to show Sea floor Spreading.
areas of oldest curst

10) Explain subduction.
Hint: root – sub – to go under
Subduction occurs when a more dense
Plate moves under a less dense plate. At
The boundary, this forms a deep trench.
Further back from the boundary, you would expect volcanoes on land or volcanic islands in the ocean.

11) Explain weathering.
Weathering is the breaking down of rock by physical and chemical means.

11) (CONT’D)...

11) (cont’d) Explain erosion.
Erosion is the movement of weathered material cause by wind, water, glacier, and gravity

12) The puzzle-like fit of the continents is one of the evidences given to explain continental drift (yes, this should be one of your answers for #6!), but the continents don’t fit together perfectly. Why?
Over the millions of years that the continents have been moving apart, they have been undergoing the natural weathering forces. This weathering and erosion has begun to alter the continents from their original shapes.

13) Explain how weathering and erosion effect Earth’s surface.
Weathering and erosion generally level things out. Mountains are worn down and valleys are filled up. Sometimes, water does carve deep scars into earth as well.

14) Define the following terms: Topographic Map,
Contour Line, Contour Interval, Hachure Marks and Index Contour.
Topographic Map: a map showing the elevation of the land.
Contour Line: a line on a topographic map that connects points of equal elevation
Contour Interval: the “step up” or elevation change between two contour lines.

14) (cont’d) Define the following terms: Topographic
Map, Contour Line, Contour Interval, Hachure
Marks and Index Contour.
Hachure Marks: little “tic” marks on a contour line showing that it going down to a depression..
Index Contour: a special contour line on a topographic map that is labeled with the elevation (and is often dark/bold)

15) What is the contour interval for the map above?
20

16) Draw a topographic map that shows a steep incline.
Steep slope
(lines close together)
150
200

17) Draw a topographic map that shows a gentle incline.
150
200
Gentle slope
(lines far apart)

18) What direction is Mill River Flowing?
Northwest (note the contour line “V” points upstream)

19) What is the highest elevation on the map?
380 meters (+)

20) What is the elevation of point Z?
220 meters

THE FOLLOWING SLIDES ARE ANSWERS
TO TEST REVIEWS WE USED IN THE
PAST. MUCH OF THE MATERIAL IS THE
SAME, JUST RE-WORDED. IT MAY BE
WORTH LOOKING AT AS YOU PREPARE
FOR THIS YEAR’S TEST!

4) How do we know where the plate boundaries are?
Volcanoes and the origins of earthquakes create a dot-to-dot the really allows us to draw plate boundaries.

1) What were Wegner’s four “evidences” of Continental Drift
(and give a short explanation of what each means)?
• Continents appear to fit together like a jigsaw puzzle.
• Distribution of fossil remains over several continents.
• Similar rock layers on different continents.
• Glacial marks on different continents appear to line when the continents are moved together.

2)
There are three “plate movements” that can occur (toward each other, apart, and sliding past). Name them. Draw a sketch of each. Show what geologic features occur at each
•
Folded Mountains, Volcanic Islands, deep sea trenches
•
Mid ocean ridge, rift valley
•
Faults

3) Explain sea-floor spreading (and diagram it).
What is it used as “evidence” for?
• Sea floor spreading is evidence for plate tectonics

4) Explain the relationship between the location of volcanoes/earthquakes and plate tectonics.
• Most volcanoes and earthquakes occur along plate boundaries
• this is the “dot to dot!”

5) The earth is a constant sized sphere…However, as plates move around, crust is constantly being created and destroyed. Explain this idea (be sure to note which types of plate boundaries are involved).
• New crustal material is formed at divergent boundaries and older crustal material subducts back into the mantle at convergent boundaries

6) What causes the gigantic tectonic plates move?
Diagram it and be sure to include at least two plates moving toward each other and two moving away from each other.
• Convection currents in earths mantle cause tectonic plates to move.

7) Diagram how hot-spot volcanoes are used to determine the direction of plate movement.

8) Diagram sonar and explain how it works.
• Sound wave are sent to the ocean floor and reflect back to the source. The shape of the ocean floor determines how the sound waves are received reveling the contour of the ocean floor.

9) What causes folded mountains?
• Two continental plate colliding cause folded mountains. Continental plates have approximately the same density and do not subduct.

10) What determines if a plate will slide under another?
• Denser crustal material tends to subduct or slide under a less dense crustal material.

11) Draw the three types of convergent boundaries.
Explain the plate movement and label the crustal features.
• Two plate are moving toward one another

12) Draw a divergent boundary. Explain the plate movement and label the crustal features.
• Two ocean plates are moving away form one another.

13) What type of plate movement causes mostly earthquakes (and not much else)?
• Two plates sliding past one another at a transform boundary.

14) What type of plate movement is happening in
California?
• Two plates are sliding past one another.

15) What type of plate movement is happening in the
Himilayas (between India and the rest of Asia)?
• Two continental plates are moving toward each other forming the Himalayan mountains (folded mountains)

16) What type of plate movement is happening in the middle of the Atlantic Ocean?
• The ocean plates are moving away from each other at the Mid Atlantic Ridge.

20) What is land subsidence and give at least one cause of land subsidence.
• When the land surface sinks.
• Human and geologic activity cause land subsidence
• Mid ocean ridge is a place where land subsidence occurs

3) Compare/contrast compression and tension forces..
Compression: to push together. This would be a convergent plate boundary
Tension: to pull apart. This would be a divergent plate boundary.