Assignment 3.Please review the course web site for access dates: Click on the begin button to access the assignment and submit your answers. This covers Unit III Forces Within in the textbook (Chapters 5, 6, and 7). Chapters 5, 6, and 7 are very inter-related so some answers may be found in more than one chapter.

MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. (1 point each)

1) Among the following choices, the closest match for the East Pacific Rise is ________.    

A) the Mariana Trench            B) the Mid-Atlantic Ridge

C) the San Andreas Fault         D) the Appalachian Mountains

2) Continental rifts are associated with ________ plate boundaries.  

A) transform    B) convergent  C) divergent     D) all kinds of

3) Linear, magnetic patterns associated with mid-ocean ridges are configured as ________. 

A) normal and reversed magnetized strips roughly parallel to the ridge

B) normal and reversed magnetized strips roughly perpendicular to the ridge axis

C) reversed magnetizations along the rift valleys and normal magnetizations on the ridge

D) concentric circles about a rising plume of hot, mantle rocks and magma

4) In the early part of the twentieth century, ________ argued forcefully for the idea of continental drift.   

A) Richard Wagner      B) Alfred Wegener

C) Harry Hess              D) James Hutton

5) A global positioning system (GPS) locator at site A reveals that it is moving at 2.1 centimeters per year to the east. A second GPS locator is tracking site B, which is moving at 2.0 centimeters per year to the west. What sort of plate boundary is this?        

A) convergent

B) divergent

C) transform

D) impossible to tell based on this information alone

6) Most of the world’s ________ line(s) up along plate tectonic boundaries. 

A) volcanoes               B) very young oceanic crust

C) earthquakes            D) all of the above

7)  

Mount Hood (pictured) is part of the Cascade Range. These active volcanoes are a chain that stretches along the west coast from northern California to southern British Columbia, Canada. The Cascades are ________.

A) evidence of rifting of the North American continent

B) evidence of subduction in the Pacific Northwest of the United States

C) a product of the San Andreas Fault

D) due to a hot spot beneath Seattle

Fill in the blank. Write the word or phrase that best completes each statement or answers the question. (1 point each)

8)   

Examine the image. It shows ________, a freshwater reptile whose fossils Alfred Wegener cited as evidence of continental drift.

9) The North American plate is currently ________ in size.

10) Some kind of ________ (upward movement of less dense material and downward movement of more dense material) appears to drive the motion of plates.

11) Alaska’s Aleutian Islands formed as part of a(n) ________ along a(n) ________ boundary.

12) Slabs of oceanic lithosphere sink at subduction zones because the subducted slab is denser than the underlying asthenosphere. In this process, called ________, Earth’s gravity tugs at the slab, drawing the rest of the plate toward the subduction zone.

13) ________ was a supercontinent that existed in the late Paleozoic era of geologic time.

#9-13 Vocabulary (extra words and/or phrases are included, not all will be used)

basalt

convergent

divergent

mesosaurus

tyrannosaurus

dip-slip

slip-slip

growing

shrinking

convection

volcanic island arc

slab pull

slab push

Pangaea

Africa

MULTIPLE CHOICE.  Choose the one alternative that best completes the statement or answers the question. (1 point each)

14)  

Examine the graph. After a P wave (blue line) has been traveling for 5 minutes, how much distance has been covered by an S wave (red line) generated by the same earthquake?   

A) 1200 km     B) 2500 km     C) 3100 km     D) 1900 km

15) Which one of the following is true of most tsunamis?      

A) Their wave heights decrease and wavelengths increase as they move into shallower water.

B) They are usually started by sudden movement on a megathrust fault, and have wavelengths that are many kilometers long and wave heights of less than a meter.

C) They only occur in the Pacific Ocean basin.

D) They are faster than seismic surface waves.

16) Which kind of seismic wave is responsible for the most shaking (and thus, the most damage to human structures)?           

A) surface waves         B) scarp waves            C) S waves       D) P waves

17) With regard to earthquakes, what distinguishes intensity from magnitude?          

A) Intensity is a measure of how much energy is released by the earthquake, but magnitude is a rough measure of local shaking.

B) Magnitude cannot be measured from a distance using seismograms.

C) Magnitude is a measure of how much energy is released by the earthquake, but intensity is a rough measure of local shaking.

D) Intensity and magnitude both depend on people reporting their experiences.

18) How did the Himalayas form?      

A) stretching of the crust to produce fault block mountains

B) collision of India and Eurasia

C) collision and accretion of many small terranes including island arcs and microcontinents

D) movement on a strike-slip fault

19) Where is the epicenter of an earthquake? 

A) wherever we find the most damage from the earthquake

B) on Earth’s surface, directly above the hypocenter

C) where the rock on either side of a fault moves

D) where the fault meets Earth’s surface

20)   

What kind of dip-slip fault is illustrated in this figure?           

A) thrust fault              B) reverse fault                        C) normal fault                        D) strike-slip fault

Fill in the blank. Write the word or phrase that best completes each statement or answers the question. (1 point each)

21) ________ are destructive sea waves induced by earthquakes.

22) In general, buildings constructed on ________ fare better in an earthquake than buildings constructed on ________, as this material amplifies seismic shaking.

23) Horsts and grabens are bounded by ________.

24) The difference between a continent and a microcontinent is ________.

25) The ________ is a layer in Earth’s interior that is in a liquid state.

26) Earth has ________ distinct kinds of crust.

27) ________ are accreted crustal fragments that have distinct geologic histories from that of the adjoining crust.

#21-27 Vocabulary (extra words and/or phrases are included, not all will be used)

two

four

tsunami

spit

pumice

normal faults

reverse faults

size

shape

outer core

inner core

terranes

terrains

parasitic cones

solid bedrock

loose sediments

MULTIPLE CHOICE.  Choose the one alternative that best completes the statement or answers the question. (1 point each)

28) Which type of basaltic lava flow has a fairly smooth, unfragmented, ropy surface?        

A) pahoehoe    B) scoria          C) pumice        D) aa

29)   

Parícutin is an example of a ________.          

A) shield volcano        B) cinder cone             C) volcanic neck          D) composite volcano

30)   

Mauna Loa, a volcano in Hawaii, is an excellent example of a ________.    

A) shield volcano        B) volcanic neck          C) cinder cone            D) composite volcano

31) Multiple plutons can coalesce (merge) to form a(n) ________.    

A) batholith                 B) dike            C) sill               D) neck

32) Which of the following factors help determine whether a volcanic eruption will be violent or relatively quiescent?           

A) temperature

B) amount of dissolved gases in the lava

C) composition of the lava     

D) all of the above

33) If you want to melt a rock, even partially, there are three methods you can employ. Which of the following is NOT a way that melting is triggered in rocks in the Earth?  

A) adding water                                   B) adding heat

C) releasing pressure                D) removing water

34) The Columbia Plateau in the northwestern United States is an excellent example of ________.  

A) pyroclastic flow deposits                B) flood basalts

C) an eroded shield volcano                D) a caldera

Fill in the blank. Write the word or phrase that best completes each statement or answers the question.

35) The difference between lava and magma is lava is found ________ Earth’s surface; whereas magma is ________ the surface.

36) ________ are pyroclastic materials, over 2.5 inches  in diameter, ejected from volcanoes as liquid droplets; they cool and form a solid crust before they land.

37) ________ is type of basaltic lava flow has its surface covered with sharp-edged, angular blocks and rubble.

38) The Year Without A Summer (1816) was triggered by the eruption of ________ in 1815 and that volcano’s explosive injection of sulfate particles into the stratosphere, screening out incoming sunlight.

39)   

Shiprock, New Mexico, is a classic example of ________.

40) When magma intrudes other rocks, it may ________ before reaching the surface, producing intrusions called plutons.

#35-40 Vocabulary (extra words and/or phrases are included, not all will be used)

lava bombs

lava tubes

at or near

ash

Mount Tambora

aa

pahoe-hoe

cool and crystallize/solidify

Mount Saint Helens

Pyroclastic material

a volcanic neck

below

a composite volcano

evaporate and turn to gas