Rocks

Question 1

Minerals

Answer 1

Minerals are inorganic substances that occur naturally at or below the earths surface

Question 2

Rocks

Answer 2

Rocks are consolidated materials composed from grains of one or more minerals

Question 3

Igneous rocks

Answer 3

These are rocks that are formed when magma is ejected from the earths interior. for example, granite and gabbro

Question 4

Two types of igneous rocks

Answer 4

Extrusive igneous and intrusive igneous

Question 5

explanition of two types of igneous rocks

Answer 5

Extrusive igneous- these are rocks that form on the earths surface, which usually have fine texture due to fast cooling, which makes their crystals form faster but smaller.

intrusive igneous- these are rocks that are formed below the earths surface, which have coarse texture due to fast cooling this enables them to have large crystals

Question 6

Sedimentary rocks

Answer 6

Rocks fromed when particles of other rocks laid down are compressed into layers or when animal and plants remains are buried, compressed and compacted, eg limestone and sand stone

Question 7

Metamorphic rocks

Answer 7

Rocks that have changed their physical appereance and chemical properties
due to subjection of great heat and pressure eg gnesis and marble

Question 8

Significance of Rocks

Answer 8

1.
Rocks weather to form soil which is important in agriculture.

2.
Form aquifers which store ground water which forms springs
which form rivers and wells which provide water for domestic and
industrial use.

3.
Some rocks are sources of building materials e.g. igneous rocks
are used to make ballast

.Source of minerals e.g. oil and coal is associated with sedimentary
rocks

5. They are a tourist attraction which brings foreign exchange e,g
   high volcanic peaks such as those of Mt. Kenya

6.
Pumice is used as a scrubbing stone.

Question 9

Weathering

Answer 9

• Mechanical breakdown or chemical decay of rocks “in situ” (without movement)

Question 10

Agents of weathering

Answer 10

animals, people, plants and the weather elements

Question 11

physical weathering

Answer 11

caused by effects of changing temp on rocks, causing the rock to break apart sometimes assisted by water

Question 12

2 types of physical weathering (explain)

Answer 12

freeze thaw- this is when water seeps into the cracks of a rock, freezes it and expands, eventually breaking the rock apart

exfoliation- the peeling of rocks due to heating and cooling

Question 13

chemical weathering

Answer 13

chemical weathering occurs when rain water reacts with the mineral grains of rocks, to form new rocks

Question 14

biological weathering

Answer 14

this is when living things contribute to the weathering process. Eg when an animal tramples on a rock breaking it down or when a plant uses its roots to penetrate though a rock which also breaks it apart

Question 15

THE ROCK CYCLE :

Answer 15

a representation of the changes
between the three rock types and the processes causing

Question 16

how does the rock cycle go?

Answer 16

Rocks in the Earth’s crust are always changing. When rocks are exposed to weathering, they break down into small pieces called sediments. These sediments are carried away by wind and water, and over time, they form new sedimentary rocks.

If these rocks get buried deep inside the Earth, heat and pressure can turn them into metamorphic rocks. Sometimes, they even melt into magma, which cools down and forms igneous rocks. These new rocks can then be weathered and broken down again, starting the cycle all over.

This continuous process of rock formation and destruction is called the rock cycle.