1. How is clastic sedimentary rock different from chemical sedimentary rock?
Clastic sedimentary rock is formed from rock fragments that are cemented together by
calcite or quartz. Chemical sedimentary rock is made of dissolved minerals that
eventually crystallize.
2. How does limestone form?
Limestone is formed from the remains, or fossils, of animals that once lived in the ocean.
3. How do rocks recrystallize?
Rocks recrystallize when the crystals of the minerals change in composition.
4. You are walking on land where a volcano was once active. You pick up a rock that is
smooth and appears to have no crystals. How do you think this rock was formed?
The rock is an extrusive igneous rock that was made from lava and that cooled very
quickly.
5. What is the difference between composition and texture?
Composition is the minerals of which a rock is made. Texture is the appearance of the
rock based on the arrangement of the minerals from which it is made.
6. How does the rate at which magma cools affect its texture?
The more time magma has to cool, the larger its crystals are. If magma cools quickly, its
crystals are very small or hardly even visible.
7. How can you tell if a rock is a sedimentary rock and not a nonfoliated metamorphic
rock like quartzite?
A sedimentary rock may have layers, while quartzite will not have layers but have a
shiny, glittery appearance.
8. What is the difference between deformation and stratification?
Stratification will appear in layers. It is the process by which sediment is laid down layer
by layer. Deformation will not be in layers, but will appear in folds and bends in the rock.
9. Imagine you need to make a tool from a very large rock. You can choose between a
foliated rock and a nonfoliated rock. Which would you choose and why?
Because the foliated rock is arranged in bands, it would probably be easier to break.
10. Describe the difference between how foliated and nonfoliated rock are formed.
When heat and pressure are applied to certain metamorphic rock, if the minerals do not
change, the minerals align and are arranged in layers. In nonfoliated rock the minerals
change their composition and are recrystallized.
11. List four processes that change rock from one type to another.
weathering, changes in pressure, melting, and cooling
12. What are the three main classes of rock?
igneous, sedimentary, and metamorphic
13. How does halite form?
It forms when sodium and chlorine ions become so concentrated in shallow bodies of
water that halite crystallizes from the solution.
14. Early humans used rocks as tools to make other things as well as to construct
buildings. Why was it better for them to use rocks than another material such as wood?
Rocks are hard and they have the ability to last over time as compared to wood, which
would more easily decompose. Essays might also include that because of rock’s
properties they can easily shape other materials.
Answers to the Concept Map
a. igneous rock
b. composition
c. texture
d. dikes
e. erode
f. conglomerate
g. sedimentary rock