Unit 6 Rocks
Overview - The rock cycle, which is continual in nature, explains the formation of minerals and
rocks. Fossils provide evidence of constant environmental change.
Standards:
Students will investigate the scientific view of how the earth’s surface is formed.
Investigate the contribution of minerals to rock composition.
Classify rocks by their process of formation.
Describe how fossils show evidence of the changing surface and climate of the Earth.
Students will describe various sources of energy and with their uses and conservation.
Identify renewable and nonrenewable resources.
Students will investigate the scientific view of how the earth’s surface is formed.
Compare and contrast the Earth’s crust, mantle, and core including temperature, density,
and composition.
Describe processes that change rocks and the surface of the earth.
Explain the effects of physical processes (plate tectonics, erosion, deposition, volcanic
eruption, gravity) on geological features including oceans (composition, currents, and
tides).
Questions - Students will be asked to answer these questions throughout this unit of study.
#1
#2
#3
#4
#5
How are rocks formed?
How are rocks classified?
How can rocks change from one type to another?
Is the rock cycle really a cycle? Explain your answer.
How are rocks used by 6th graders?
ROCKS
1. Rocks and minerals are not the same thing.
2. Rocks are composed of minerals which are naturally existing chemical compounds.
3. Rocks and minerals are naturally occurring substances that are usually crystalline and solid
4. Rocks are classified based on how they formed and their mineral composition.
5. Rocks can be distinguished into many different types, based on their origins and
compositions.
6. List five ways we use rocks and minerals in our everyday life. Toothpaste, cars, toilets,
computers, and phones.
7. What are the three main types of rocks? Igneous, Metamorphic, and Sedimentary.
SEDIMENTARY ROCKS
8. Sedimentary rocks form by cementation and compaction.
9. Sedimentary rocks are formed by the ongoing deposition of rocks and other sediments that are
cemented together.
10. Usually after burial, deposited sediment undergoes lithification (the processes that turn
sediment into a rock).
11. Lithification includes cementation and compaction.
12. Coal is a black, sedimentary rock that is formed from cementation and compaction.
13. Limestone, shale, and sandstone are all examples of sedimentary rock.
14. Sediment from weathered rock is transported and deposited elsewhere such as at the beach,
or in a delta, or in the deep sea.
15. Sedimentary rocks are the most abundant rock on Earth’s Surface.
IGENOUS ROCKS
16. Igneous rocks are formed from molten rocks that has cooled and hardened.
17. Magma (or Lava) cool and crystallize to form igneous rock.
18. There are two types of Igneous Rock. Intrusive and Extrusive
19. Extrusive Igneous Rock is formed from lava, which is on the surface.
20. Intrusive Igneous Rock is formed from magma, which is below the surface.
21. What is the difference between magma and lava? Lava is on the earth surface and magma is
below.
22. Molten rock that flows on the surface of the Earth is lava.
23. Molten rock that is below the surface of the Earth is Magma.
24. Where are many Igneous Rocks found? Divergent boundaries and volcanoes.
25. Igneous rocks are dominated by silicate minerals.
26. Molten rock with lower amounts of silica flows faster than molten rock with higher amounts
of silica.
27. If lava has more silica, it will move slower than lava with less silica.
28. Igneous rock undergoes weathering (or breakdown) to form sediment.
29. Of the three types of rocks, igneous rocks are the hardest.
30. The Stone Mountain granite is a relatively small granite pluton that covers an area less than
a county in size.
31. Stone Mountain is made of granite and is an igneous rock.
METAMORPHIC ROCKS
32. Metamorphic rocks are formed by heat and pressure.
33. As the metamorphic rock is buried more deeply, temperatures and pressures continue to rise.
34. If the temperature becomes hot enough, a metamorphic rock will melt. The molten rock is
called magma.
35. Large amounts of metamorphic rocks are usually found underneath large mountain chains.
36. A magma intrusion will heat up the surrounding rocks and form new metamorphic rocks.
37. Small amounts of metamorphic rocks are usually found near magma intrusions.
38. If the sedimentary rock is buried deep in the crust under more and more sediment, often due
to plate tectonic movements, the heat and pressure causes metamorphism to occur. This
transforms the sedimentary rock into a metamorphic rock
39. Igneous rocks can undergo metamorphism (as a result of heat and pressure) to form
metamorphic rocks.
ROCK CYCLE
40. Rocks at the Earth’s surface weather, forming sediments that are buried. These sediments
are compacted, heated, and often recrystallized into new rock.
41. The rock cycle explains how one rock type can be transformed into another.
42. The Rock Cycle is continuous; it never ends.
43. Any rock type can undergo weathering to form sediment.
44. Igneous, metamorphic and sedimentary rocks undergo weathering.
45. The beginning of the rock cycle is not possible to identify because it is a never ending cycle.
46. Fill in the Rock Cycle below
FOSSILS
47. A fossil is a remnant or trace of an organism from the past, such as a skeleton or leaf
imprint.
48. Fossils are embedded and preserved in the earth's crust.
49. A Trace Fossil is a fossil of a footprint, trail, burrow, or other trace of an animal rather than
of the animal itself
50. A footprint of an ancient animal in a rock is called a trace fossil.
51. Large animals occasionally became trapped in tar and become a fossil.
52. Fossils, the remains of organisms preserved in sedimentary rocks, are part of the evidence
scientists use to infer changing conditions at the Earth’s surface through time.
53. Oil and Natural Gas are formed from ocean plankton that died millions of years ago.
54. Coal, Natural Gas, and Oil are all examples of fossil fuels.
55. Petrified wood is a fossil.
56. Petrified wood forms when water with natural minerals slowly fills the pores of wood. Over
thousands of years the wood slowly decomposes leaving behind the minerals from the water.
The minerals harden and form a rock that looks exactly like the original wood.
57. How much wood is actually located in petrified wood? 0%.
58. The geologic column is how geologists have organized the entire history of the Earth in
chronological order.
59. Superposition states that older layers of rock are below younger layers of rock.
60. Radiometric dating is how geologists determine the age of rocks by measuring the decay of
atoms.
61. Radiometric dating is the most accurate way to date rocks and fossils.
CAVES
62. Caves form from slightly acidic ground water slowly seeping through slightly basic rocks
underground. The acid slowly caused the rock to dissolve and wash away.
63. Caves often form where ancient seas once existed. The seashells left behind for millions of
years form limestone and this rock reacts with acids in rain water to form large underground
caves.
64. Caves have rock structures that look like giant icicles called stalactites and stalagmites.
65. Stalactites form on the ceilings of caves.
66. Stalagmites form on the ground of caves.
67. How do stalagmites and stalactites grow? Water that has natural minerals floating inside
slowly drip from the ceilings of caves. Over thousands of years the minerals slowly harden.
VOCABULARY
1. Rock Cycle - the continuous process by which rocks are created, changed from one form to
another, destroyed, and then formed again
2. igneous rock - formed when magma or lava cools and hardens. Basalt and obsidian are
igneous rocks
3. intrusive igneous rock – formed from cooled and hardened magma inside the earth. These
typically have large crystals because they cool slowly
4. extrusive igneous rock - formed from cooled and hardened lava on the surface of the Earth.
5. metamorphic rock - formed under the surface of the earth from the change that occurs due to
intense heat and pressure. Gneiss and marble are examples of metamorphic rock
6. sedimentary rock - formed from particles of sand, shells, pebbles, and other fragments that
accumulates in layers and over a long period of time hardens into rock. Limestone is an example
of sedimentary rock
7. fossil - a remnant or trace of an organism from the past, such as a skeleton or leaf imprint,
embedded and preserved in the earth's crust
8. radiometric dating - a method of finding the age of items by determining the relative
proportions of particular radioactive isotopes present in a sample
9. The Law of Superposition - A general law stating that in any sequence of sediments or rocks
that has not been overturned, the youngest sediments or rocks are at the top of the sequence and
the oldest are at the bottom
10. pressure - the continuous physical force exerted on or against an object by something in
contact with it
11. magma - hot fluid or semi fluid material (molten rock) below or within the earth's crust.
12. lava - Molten rock that flows on the surface of the earth
13. stalagmite - deposits of minerals that form into cave structures that emerging from the
ground and stand up like a traffic cone
14. stalactite - deposits of minerals that form into cave structures that hang from the ceilings of
caves like icicles
15. amber - the fossilized resin from ancient trees
16. silica – a natural element found within the Earth’s crust. The amount of silica in magma
determines the speed of the lava. An increase in the amount of silica in lava, slows the lava
down
17. trace fossil - a fossil of a footprint, trail, burrow, or other trace of an animal rather than of
the animal itself
18. petrification - the process of turning some plant material into stone by infiltration with water
carrying mineral particles without changing the original shape
19. petrified wood - a fossil that forms when plant material is buried by sediment, dissolves over
time, and sediment replaces the original plant material.
20. fossil fuels - a natural fuel such as coal or gas, formed in the geological past from the
remains of living organisms
21. Lithification – the process that turns sediment into rock