2. Choose the correct statement relating to eruptions on the ocean floor.

Very hot basaltic lavas pour out along convergent zones to form pillow lavas.
Very hot basaltic lavas pour out along convergent zones to form aa lavas.
Very hot basaltic lavas pour out along divergent zones to form aa lavas.
Very hot basaltic lavas pour out along divergent zones to form pillow lavas.

3. Hot spots, created by mantle plumes, are

only found on divergent boundaries; they erupt basaltic lavas and form shield volcanoes
usually found on convergent boundaries; they may erupt basaltic lavas and form composite volcanoes.
often found in the middle of plates; they erupt basaltic lavas and form shield volcanoes.
found in the middle of plates; they only erupt andesitic lavas and form composite volcanoes.

4. The large, tall volcanoes that lie on convergent plate boundaries are

more explosive and called cinder cones.
more explosive and called composite volcanoes.
more explosive and called shield volcanoes.
usually composed of basalt and called composite volcanoes.

5. Alternating ejections of lava flows and

explosively erupted fragments create composite volcanoes.
explosively erupted fragments create cinder cones.
explosively erupted fragments create shield volcanoes.
steam eruptions create composite volcanoes.

6. The most common type of gases issued from volcanoes are

water vapor, carbon dioxide and fluorine.
water vapor, carbon dioxide and chlorine.
water vapor, carbon dioxide and sulfur.
chlorine, carbon dioxide and sulfur.

7. The explosiveness of an eruption is influenced mainly by the

temperature and depth of the magma.
temperature and chemical composition of the magma.
depth and chemical composition of the magma.
pressure and depth of the magma.

8. Magmas with higher viscosities tend to (see Helps & Hints)

be cooler and heavier.
be hotter and heavier.
flow faster and degas easily.
trap gases leading to a greater potential for explosiive activity.

9. Choose the correct response pertaining to the manner in which viscosity can influence the surface characteristics of lava.

Runny, fluid lava that forms a billowy surface is called aa lava.
A degassed lava with a high viscosity and jagged surface is called pahoehoe lava.
A lava with very a very low viscosity and a jagged surface is called aa lava.
Runny, fluid lava that forms a billowy surface is called pahoehoe lava.

10. Explosive volcanic eruptions that eject lots of material will over a long period of time

tend to build steep cones because some of the ejecta piles up.
only blow big craters in the ground.
always be followed by very fluid flows.
tend to build shield volcanoes.

11. Cinders are larger than fragments of ash mainly because the

explosion that creates them is stronger.
explosion that creates them is weaker.
magma they are created from is more viscous (stickier).
magma they are created from is less viscous (stickier).

12. Volcanoes are associated mainly with

divergent, convergent boundaries and hot spots.
convergent boundaries only.
divergent boundaries and hot spots.
convergent boundaries and hot spots only.

13. Obsidian is a rock

of mainly glass that is forcefully ejected in an airborne manner from a volcano.
that is a low viscosity, silica-rich, material that is forcefully ejected in an airborne manner from a volcano.
that is glass-like (glassy) which usually flows slowly out after an explosive eruption.
from low viscosity lavas that usually flows out before an explosive eruption.

14. Volcanic domes are usually made of

fluid lavas created in the aftermath of powerful eruptions.
sticky lavas created in the aftermath of powerful eruptions.
low viscosity lavas that pile-up before an explosive eruption.
intermediate viscosity lavas that pile-up before an explosive eruption.

15. The short range forecasting of volcanic eruptions is best done by

ground deformation studies.
the seismic monitoring of earthquakes within the volcano.
studying the history of the volcano: what it has done in the past it will do in the future.
ground deformation studies and the seismic monitoring of earthquakes within the volcano.

16. Practical ramifications of volcanic activity are the

interesting landforms that are produced.
rich soils generated and geothermal energy.
additional materials that are added to the coastlines of continents.
mountain ranges that are formed and their adverse influence on the location of large population centers.

Lesson 14 "Intrusive Igneous Rocks"

17. Choose the incorrect choice. Whether rock melts while it is in the crust or upper mantle depends upon

the temperature, pressure and the type of rock.
the temperature, pressure and water content of the rock.
the temperature, pressure and composition of the rock.
if it rises to erupt or sinks to join the molten core.

18. The Earth's interior heat is probably generated by (see #25 Study Focus)

the original formation of the Earth, radioactive substances and its rotation.
the tidal effects of the sun and moon and its rotation.
the original formation of the Earth, radioactive substances and tidal effects of the sun and moon.
compression of gravity, rotation and radioactive substances.

19. Magma can create intrusions

of various size and shapes called plutons.
of various size and shapes called subterranean volcanoes.
if ejected onto the surface they are called plutons.
if ejected onto the surface they are called extrusive plutons.

20. Which of the following is a correct description of types of plutonic rocks?

Those that contain abundant iron and magnesium are called mafic; granite for example.
Those that contain abundant silica and aluminum are called felsic; gabbro for example.
Those that are mixtures of felsic and mafic are called intermediate; gabbro for example.
Those that contain abundant silica and aluminum are called felsic, granite for example.

21. Differences between intrusive rock and their extrusive counterparts are found mainly in their

compositions and cooling rates.
textures and cooling rates.
textures and compositions.
crystal size and composition.

22. Intrusive rock tend to cool

faster than extrusive rock eliminating the chance for large crystals to form.
slower than extrusive rock eliminating the chance for larger crystals to form.
slower than extrusive rock which allows larger crystals to form.
faster than extrusive rock which allows larger crystals to form.

23. The study of the texture of intrusive rocks does not give information about the

depth where the rock formed.
temperatures where the rock formed.
composition of the rock.
source of heat that originally melted the rock.

24. As magma cools, the first minerals to crystallize are

olivine and calcium plagioclase; the last are pyroxene and mica.
olivine and calcium plagioclase; the last are pyroxene and quartz.
olivine and calcium plagioclase; the last are potassium feldspar and quartz.
mica and sodium plagioclase; the last are potassium feldspar and quartz.

25. The actual temperature at which magma forms depends on the

depth only; the greater the depth, the lower the temperature.
depth only; the shallower the depth, the higher the temperature.
amount of water available; more water means a lower melting temperature
amount of water available; more water means a higher melting temperature.

26. Magma generated at

divergent zones is basaltic; at subduction zones it is more andesitic.
divergent zones is andesitic; at subduction zones it is more dioritic.
divergent zones is dioritic; at subduction zones it is more andesitic.
the ocean ridges and subduction zones is only basaltic.

27. Magma rises along divergent boundaries mainly

by melting its way upward.
as crustal rock is pulled apart.
by pushing the rock aside.
all the above.

28. Magma rises along convergent boundaries by (see Helps & Hints).

pushing the rock aside.
stoping or fracturing the surrounding rock and engulfing it.
melting its way upward.
all the above.

29. Intrusions are basically classified by their size and shape. Choose the incorrect association.

Dikes cut across pre-existing rock and are sheet-like.
Sills intrude between layers and lie parallel to the pre-existing beds.
The largest plutons are called "reservoir rock".
Some larger plutons are called stocks and batholiths.

30. Rocks that make-up many plutons in the far western United States tend to weather and erode more

slowly, because they are crystalline and have intermediate compositions.
slowly, because they are crystalline and have mafic compositions.
quickly, because they are crystalline and have mafic compositions.
quickly, because they are crystalline and have intermediate compositions.

Prepared by: Mike Mitchell

Be sure to review your quizzes before taking the test.