Page 122 - Active Science 5 Ebook and Activity

Let’s Pronounce Together

sedimentary metamorphic igneous accumulation feldspar

graphite debris granite obsidian pumice
conglomerate gneiss quartzite pyrite

LET’S
REVISE

• Rocks formed by cooling of lava are called igneous rocks.

• Sedimentary rocks are formed from deposits of grains of rocks, shells and skeletons carried
by streams and rivers.
• When sedimentary and igneous rocks get modified by pressure or heat or both, metamorphic

rocks are formed.
• Some rocks rich in one particular type of metal are called ores.

• Rocks are made up of minerals. Minerals are found inside the earth.
• Slow cooling of lava forms granite and quick cooling forms obsidian.

• Sandstone is made of fine particles and conglomerate is made of coarse grains.
• Quartzite is hard and weather resistant.

• Metallic minerals have lustre.

Glossary

• Igneous rocks : Rocks formed when lava cools down.
• Sedimentary rocks : Rocks formed due to deposition and binding of layers of mud,
clay, sand and pebbles.
• Metamorphic rocks : Rocks formed by effect of pressure and heat or both on igneous
and sedimentary rocks.
• Minerals : Chemicals of which rocks are made.
• Ores : Mixture of rocks which are rich in one particular type of metal.
• Gems : Precious stones used to make jewellery and ornaments.

Practice Time

A. Choose the correct option.

1. Igneous rocks were formed due to_______.
a. tides b. volcanoes

c. storms d. earthquakes

122 Active Science-5