PPT: Rocks, The Rock Cycle and Soil | Science Olympiad Class 6 PDF Download

 Page 1


Rocks, The 
Rock Cycle 
and Soil
Page 2


Rocks, The 
Rock Cycle 
and Soil
Igneous Rocks
What Makes Rocks Different?
Rocks differ from one another because they were 
formed in different ways. Each type has unique 
characteristics based on its formation process. 
Geologists are scientists who study rocks. In the 
next few topics you are going to be a geologist.
Page 3


Rocks, The 
Rock Cycle 
and Soil
Igneous Rocks
What Makes Rocks Different?
Rocks differ from one another because they were 
formed in different ways. Each type has unique 
characteristics based on its formation process. 
Geologists are scientists who study rocks. In the 
next few topics you are going to be a geologist.
What Are Igneous Rocks?
Origin of 'Igneous'
The word 'igneous' means fire. Igneous rocks come from magma 
that has cooled into solid rock. Magma is hot, like a fire.
Magma to Rock
When magma cools it turns into a solid. This process is called 
solidification.
Extrusive Igneous Rocks
Some magma comes out at the surface as lava. When lava cools, 
it solidifies into an extrusive igneous rock like basalt.
Intrusive Igneous Rocks
Some magma stays inside the Earth's crust, cooling slowly to 
form intrusive igneous rocks like granite.
Page 4


Rocks, The 
Rock Cycle 
and Soil
Igneous Rocks
What Makes Rocks Different?
Rocks differ from one another because they were 
formed in different ways. Each type has unique 
characteristics based on its formation process. 
Geologists are scientists who study rocks. In the 
next few topics you are going to be a geologist.
What Are Igneous Rocks?
Origin of 'Igneous'
The word 'igneous' means fire. Igneous rocks come from magma 
that has cooled into solid rock. Magma is hot, like a fire.
Magma to Rock
When magma cools it turns into a solid. This process is called 
solidification.
Extrusive Igneous Rocks
Some magma comes out at the surface as lava. When lava cools, 
it solidifies into an extrusive igneous rock like basalt.
Intrusive Igneous Rocks
Some magma stays inside the Earth's crust, cooling slowly to 
form intrusive igneous rocks like granite.
What Are Igneous Rocks Made Of?
Mineral Composition
All igneous rocks are made of minerals. Each 
mineral consists of different substances, 
primarily silica, oxygen, aluminium, 
magnesium and iron, which combine in 
various ways.
The most important characteristic of all 
igneous rocks is that they are crystalline. 
Crystals form when minerals cool down from 
their molten state.
Crystal Size Matters
When magma cools slowly deep below Earth's 
surface, large visible crystals form. This 
creates intrusive igneous rocks like granite, 
which has different coloured crystals of 
quartz, feldspar and mica.
When lava cools quickly at the surface, it 
forms extrusive igneous rocks like basalt with 
crystals too small to see with the naked eye.
Page 5


Rocks, The 
Rock Cycle 
and Soil
Igneous Rocks
What Makes Rocks Different?
Rocks differ from one another because they were 
formed in different ways. Each type has unique 
characteristics based on its formation process. 
Geologists are scientists who study rocks. In the 
next few topics you are going to be a geologist.
What Are Igneous Rocks?
Origin of 'Igneous'
The word 'igneous' means fire. Igneous rocks come from magma 
that has cooled into solid rock. Magma is hot, like a fire.
Magma to Rock
When magma cools it turns into a solid. This process is called 
solidification.
Extrusive Igneous Rocks
Some magma comes out at the surface as lava. When lava cools, 
it solidifies into an extrusive igneous rock like basalt.
Intrusive Igneous Rocks
Some magma stays inside the Earth's crust, cooling slowly to 
form intrusive igneous rocks like granite.
What Are Igneous Rocks Made Of?
Mineral Composition
All igneous rocks are made of minerals. Each 
mineral consists of different substances, 
primarily silica, oxygen, aluminium, 
magnesium and iron, which combine in 
various ways.
The most important characteristic of all 
igneous rocks is that they are crystalline. 
Crystals form when minerals cool down from 
their molten state.
Crystal Size Matters
When magma cools slowly deep below Earth's 
surface, large visible crystals form. This 
creates intrusive igneous rocks like granite, 
which has different coloured crystals of 
quartz, feldspar and mica.
When lava cools quickly at the surface, it 
forms extrusive igneous rocks like basalt with 
crystals too small to see with the naked eye.
Sedimentary Rocks and 
Fossils
What are sedimentary rocks?
Formation Process
Sedimentary rocks form 
from accumulated 
fragments of other rocks 
that have been 
compressed and 
cemented together over 
time.
Fossil Preservation
These rocks are crucial for 
preserving fossils, 
providing us with a 
window into Earth's 
biological history.
Water's Role
Water plays a vital role in sedimentary rock formation through 
weathering, transportation, and deposition of sediments.