Page 125 - SST Class 07

Terminology

Dynamic : characterised by constant change, activity or progress
Tectonic plates : a massive, irregularly shaped slab of solid rock, generally composed of both continental
and oceanic lithosphere
Convection : the process by which heat travels through air, water and other gases and liquids
Radioactive : emitting or relating to the emission of ionising radiation or particles

Inside Story
Inside Story
g The earth is a dynamic planet because it is constantly undergoing changes inside and
outside.
g The crust is the thinnest layer of the earth and is the layer we live on.
g The upper mantle is semisolid rock called magma that flows slowly due to convection
currents.
g Any naturally occurring solid substance with a definite chemical composition is called a
mineral.

g The process that causes various organic materials and minerals to settle in a place is
termed as sedimentation.

g Rocks are widely used in the construction of roads, houses and buildings.
g Throughout the geological period of millions of years, rocks and minerals have been
changing due to the working of the rock cycle.

A. Tick (3) the correct option.
1. The earth is made up of ____________ different layers.
(a) three (b) four (c) five
2. The mantle has been just beneath the crust, which is extended up to a depth of
_________ km below the crust.

(a) 2900 (b) 290000 (c) 29000
3. It covers 2/3 of the earth’s surface.
(a) Continental Crust (b) Oceanic Crust (c) Both (a) & (b)

4. The outer core is made of liquid iron and nickel and is between:
(a) 3,500°C–4,0000°C (b) 3,5000°C–4,000°C (c) 3,500°C–4,000°C
5. Which rock is formed through the cooling and solidification of magma or lava?

(a) Igneous Rock (b) Sedimentary Rock (c) Metamorphic Rock
6. The particles that form a sedimentary rock by accumulating are called:

(a) minerals (b) sediments (c) none of these

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