Page 39 - sst_class_07

Marble Metamorphic Used in building, floors, tile in bathrooms

Obsidian Igneous Used in making arrowheads and knives
Pumice Igneous Used in scouring, scrubbing and polishing materials

Quartz Mineral Used in making glass, electrical components, and optical lenses
Sandstone Sedimentary Used in the building industry or houses

Slate Metamorphic Used for roofs, chalk boards and patio walls

Now I Know :

ƒ The earth is made up of three layers called crust, mantle and core.

ƒ The crust is formed by solid materials called rocks.
ƒ Rocks can be put into three basic rocks types : igneous, sedimentary and metamorphic.
ƒ Rocks undergo a cycle of transformations.
ƒ Igneous rocks are formed from the cooling of molten rocks.
ƒ Sedimentary rocks are also called the stratified rocks.
ƒ Minerals are the main components of the rocks.

(Assessment of Learning Outcome)

A. Tick () the correct option :
1. Which one of the following is the thinnest layer of the earth’s interior?

(a) Mantle (b) Crust (c) Core (d) Exosphere

2. It is the innermost layer of the earth :

(a) Core (b) Mantle (c) Crust (d) None of these
3. Which one of the following is an example of minerals?

(a) Granite (b) Basalt (c) Petroleum (d) Fossils
4. This part of the earth is made up of molten metals :

(a) Core (b) Crust (c) Mantle (d) Lithosphere

5. Molten magma cools and solidifies to become:

(a) Igneous Rocks (b) Sedimentary Rocks
(c) Metamorphic Rocks (d) None of these

B. Fill in the blanks :

1. Earth is also known as the ________________.
2. The surface layer of the earth is known as the ________________.
3. ________________ are substances which occur in rocks.
4. The oldest type of all rocks is the ________________.
5. Minerals are natural ________________.

Social Studies-7 39