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LEARNING ACTIVITY SHEET IN EARTH AND LIFE SCIENCES NO. 4

Types of Rocks
Background Information for the Learners (BIL)

Rocks underpin our

lives. They make up the
solid structure of the
Earth. We live on the
rocky surface of the
planet, grow our food on
weathered debris derived
from rocks, and we obtain
nearly all of the raw
materials with which we
founded our civilization
from rocks. We use them
on a daily basis, usually
by walking or driving on
them (or on some crushed
and reconstituted version
thereof). Our homes and
office buildings are often
made of rock materials;
bricks as refined clays,
walls as reworked
gypsum, dining utensils such as plates, cups and saucers (pottery, ceramic and china),
counter tops and floors as slabs of rocks of various origins. Rocks are aggregates of
different mineral grains and can be divided into three major families or rock groupings.
After studying this module, you are expected to classify rocks into igneous,
sedimentary and metamorphic. (S11/12ES-Ib-10)
Specifically, you should be able to:
1. describe the characteristics of the three types of rocks;
2. trace the rock cycle;
3. appreciate the importance of rocks in the ecosystem and everyday living.
 Let's have some fun! Remember Sim City? You can remember the 3 rock types
using the acronym SIM (Sedimentary, Igneous, Metamorphic)!

Igneous Rocks
Igneous rocks form when magma (molten rock) cools and crystallizes, either at
volcanoes on the surface of the Earth or while the melted rock is still inside the crust. All
magma develops underground, in the lower crust or upper mantle, because of the
intense heat there.
 Igneous Rocks present near the Mayon Volcano
Source: https://walksofkulot.wordpress.com/2009/12/03/i-wokd-in-bicol/

Igneous rocks can have many different compositions, depending on the magma
they cool from. They can also look different based on their cooling conditions. For
example, two rocks from identical magma can become either rhyolite or granite,
depending on whether they cool quickly or slowly. 
The two main categories of igneous rocks are extrusive and intrusive. Extrusive
rocks are formed on the surface of the Earth from lava, which is magma that has
emerged from underground. Intrusive rocks are formed from magma that cools and
solidifies within the crust of the planet.
When lava comes out of a volcano and solidifies into extrusive igneous rock, also
called volcanic, the rock cools very quickly. Crystals inside solid volcanic rocks are
small because they do not have much time to form until the rock cools all the way,
which stops the crystal growth. These fine-grained rocks are known as aphanitic—from
a Greek word meaning “invisible.” They are given this name because the crystals that
form within them are so small that they can be seen only with a microscope. If lava
cools almost instantly, the rocks that form are glassy with no individual crystals, like
obsidian. There are many other kinds of extrusive igneous rocks. For example, Pele’s
hair is long, extremely thin strands of volcanic glass, while pahoehoe is smooth lava that
forms shiny, rounded piles. 
Intrusive rocks, also called plutonic rocks, cool slowly without ever reaching the
surface. They have large crystals that are usually visible without a microscope. This
surface is known as a phaneritic texture. Perhaps the best-known phaneritic rock is
granite. One extreme type of phaneritic rock is called pegmatite, found often in the U.S.
state of Maine. Pegmatite can have a huge variety of crystal shapes and sizes,
including some larger than a human hand.
(Retrieved from https://www.nationalgeographic.org/encyclopedia/igneous-rocks/

Examples
 Source: https://www.amnh.org/explore/ology/earth/if-rocks-could-talk2/three-
types-of-rock

Sedimentary Rocks
Sedimentary rocks are formed on or near the Earth’s surface, in contrast to
metamorphic and igneous rocks, which are formed deep within the Earth. The most
important geological processes that lead to the creation of sedimentary rocks
are erosion, weathering, dissolution, precipitation, and lithification.
 Limestones found in Brgy. Miti, Camalig, Albay
Erosion and weathering include the effects of wind and rain, which slowly break
down large rocks into smaller ones. Erosion and weathering transform boulders and
even mountains into sediments, such as sand or mud. Dissolution is a form of
weathering—chemical weathering. With this process, water that is slightly acidic slowly
wears away stone. These three processes create the raw materials for new,
sedimentary rocks.
Precipitation and lithification are processes that build new rocks or minerals.
Precipitation is the formation of rocks and minerals from chemicals that precipitate from
water. For example, as a lake dries up over many thousands of years, it leaves behind
mineral deposits; this is what happened in California’s Death Valley. Finally, lithification
is the process by which clay, sand, and other sediments on the bottom of the ocean or
other bodies of water are slowly compacted into rocks from the weight of overlying
sediments.
 Sedimentary rocks can be organized into two categories. The first is detrital rock,
which comes from the erosion and accumulation of rock fragments, sediment, or other
materials—categorized in total as detritus, or debris. The other is chemical rock,
produced from the dissolution and precipitation of minerals.
Detritus can be either organic or inorganic. Organic detrital rocks form when
parts of plants and animals decay in the ground, leaving behind biological material that
is compressed and becomes rock. Coal is a sedimentary rock formed over millions of
years from compressed plants. Inorganic detrital rocks, on the other hand, are formed
from broken up pieces of other rocks, not from living things. These rocks are often
called clastic sedimentary rocks. One of the best-known clastic sedimentary rocks is
sandstone. Sandstone is formed from layers of sandy sediment that is compacted and
lithified.
Chemical sedimentary rocks can be found in many places, from the ocean to
deserts to caves. For instance, most limestone forms at the bottom of the ocean from
the precipitation of calcium carbonate and the remains of marine animals with shells. If
limestone is found on land, it can be assumed that the area used to be under water.
Cave formations are also sedimentary rocks, but they are produced very differently.
Stalagmites and stalactites form when water passes through bedrock and picks up
calcium and carbonate ions. When the chemical-rich water makes its way into a cave,
the water evaporates and leaves behind calcium carbonate on the ceiling, forming
a stalactite, or on the floor of the cave, creating a stalagmite.
Examples

Source: https://www.amnh.org/explore/ology/earth/if-rocks-could-talk2/three-
types-of-rock

Metamorphic Rocks
 The term “metamorphosis” is most often used in reference to the process of a
caterpillar changing into a butterfly. However, the word “metamorphosis” is a broad term
that indicates a change from one thing to another. Even rocks, a seemingly constant
substance, can change into a new type of rock. Rocks that undergo a change to form a
new rock are referred to as metamorphic rocks.

Romblon: The Marble Capital of the Philippines

Source: https://www.vigattintourism.com/tourism/articles/Romblon-The-Marble-
Capital-of-the-Philippines
In the rock cycle, there are three different types of rocks: sedimentary, igneous,
and metamorphic. Sedimentary and igneous rocks began as something other than rock.
Sedimentary rocks were originally sediments, which were compacted under high
pressure. Igneous rocks formed when liquid magma or lava—magma that has emerged
onto the surface of the Earth—cooled and hardened. A metamorphic rock, on the other
hand, began as a rock—either a sedimentary, igneous, or even a different sort of
metamorphic rock. Then, due to various conditions within the Earth, the existing rock
was changed into a new kind of metamorphic rock.
The conditions required to form a metamorphic rock are very specific. The
existing rock must be exposed to high heat, high pressure, or to a hot, mineral-rich fluid.
Usually, all three of these circumstances are met. These conditions are most often
found either deep in Earth’s crust or at plate boundaries where tectonic plates collide. In
order to create metamorphic rock, it is vital that the existing rock remain solid and not
melt. If there is too much heat or pressure, the rock will melt and become magma. This
will result in the formation of an igneous rock, not a metamorphic rock.
 Consider how granite changes form. Granite is an igneous rock that forms when
magma cools relatively slowly underground. It is usually composed primarily of the
minerals quartz, feldspar, and mica. When granite is subjected to intense heat and
pressure, it changes into a metamorphic rock called gneiss.
Slate is another common metamorphic rock that forms from shale. Limestone,
a sedimentary rock, will change into the metamorphic rock marble if the right conditions
are met.
Although metamorphic rocks typically form deep in the planet’s crust, they are
often exposed on the surface of the Earth. This happens due to geologic uplift and the
erosion of the rock and soil above them. At the surface, metamorphic rocks will be
exposed to weathering processes and may break down into sediment. These sediments
could then be compressed to form sedimentary rocks, which would start the entire cycle
anew.
Examples

Rock Cycle
The Rock Cycle is a group of changes. Igneous rock can change into
sedimentary rock or into metamorphic rock. Sedimentary rock can change into
metamorphic rock or into igneous rock. Metamorphic rock can change into igneous or
sedimentary rock.
Igneous rock forms when magma cools and makes crystals. Magma is a hot
liquid made of melted minerals. The minerals can form crystals when they cool. Igneous
rock can form underground, where the magma cools slowly. Or, igneous rock can form
above ground, where the magma cools quickly.
 When it pours out on Earth's surface, magma is called lava. Yes, the same liquid
rock matter that you see coming out of volcanoes.
On Earth's surface, wind and water can break rock into pieces. They can also
carry rock pieces to another place. Usually, the rock pieces, called sediments, drop from
the wind or water to make a layer. The layer can be buried under other layers of
sediments. After a long time, the sediments can be cemented together to make
sedimentary rock. In this way, igneous rock can become sedimentary rock.
All rock can be heated. But where does the heat come from? Inside Earth there
is heat from pressure (push your hands together very hard and feel the heat). There is
heat from friction (rub your hands together and feel the heat). There is also heat from
radioactive decay (the process that gives us nuclear power plants that make electricity).
So, what does the heat do to the rock? It bakes the rock.
Baked rock does not melt, but it does change. It forms crystals. If it has crystals
already, it forms larger crystals. Because this rock changes, it is called metamorphic.
Remember that a caterpillar changes to become a butterfly. That change is called
metamorphosis. Metamorphosis can occur in rock when they are heated to 300 to 700
degrees Celsius.
 When Earth's tectonic plates move around, they produce heat. When they
collide, they build mountains and metamorphose (met-ah-MORE-foes) the rock.
The rock cycle continues. Mountains made of metamorphic rocks can be broken
up and washed away by streams. New sediments from these mountains can make new
sedimentary rock.
The rock cycle never stops.
(Retrieved from http://www.cotf.edu/ete/modules/msese/earthsysflr/water.html)

Most Essential Learning Competency:

Classify rocks into igneous, sedimentary and metamorphic. S11/12ES-Ib-10

Activity 1: Tracing the Rock Cycle

Direction: The rock cycle illustrates the ways rocks change from one form to another.
There are several different processes in the rock cycle which cause rocks to change
form. Write the terms melting, heat and pressure, compaction and cementation,
solidifying, weathering and erosion in the correct blanks for letters A to E). For
numbers 1-5, name the type of rock or kind of material. Fill in these terms as you
proceed in a clockwise direction on the diagram. Once you have done, you have
created a finished map of the rock cycle.

Illustrated by: Frances C. Morales

Answer the following questions:
1. What forces change sedimentary rock into metamorphic rock?
2. How is molten rock formed, and what type of rock does it create when it
hardens?
3. Describe how sediments form
4. Provide an example of each of the three rock types.
5. Explain why the rock cycle is referred to as a “cycle”.
Activity 2: Rock Around the Rock Cycle
Directions: In the rock cycle, rocks break down and build up, slowly changing from one
type to another. Rock around the rock cycle and find out how these changes take
place.
Part 1: Read each group of sentences below and choose the correct words to complete
them. Write each word in its corresponding blank.
Part 2: Using the completed diagram, explain how each type of rock is formed.

1. How igneous rock is

formed?
2.

How
sedimentary
rock is formed?
3. How metamorphic rock is
formed?

Activity 3: Comic Quiz

Directions: Read the comic strip. Then, answer the given questions that follow.
1. When rocks are affected by weathering and erosion, they change into which of
the following?
A. Lava B. Magma C. Sediment D. Igneous rock

2. What type of rock is formed when sediment is compacted and cemented?

A. Igneous rock B. Sedimentary rock C. Metamorphic rock D. Magma

3. What is formed when heat and pressure are applied to a sedimentary rock?
A. Igneous rock B. Sedimentary rock C. Metamorphic rock D. Magma

4. When melting of a metamorphic rock occurs, it changes into which of the

following?
A. Lava B. Magma C. Sediment D. Igneous rock

5. What kind of rock is formed when magma hardens?

A. Lava B. Magma C. Sediment D. Igneous rock

Activity 4. Do your part!

Write an essay.
As a student, what will
you do to make other
students appreciate the
importance of rocks?
Reflection
1. I learned that
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2. I enjoyed most on
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3. I want to learn more on
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Student’s Signature over Printed Name

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Parent’s Signature over Printed Name

Prepared by:
ASELA S. OCFEMIA
Mauraro High School