Rocks & its Types | Science for Grade 4 PDF Download

Introduction

Today, we're going to explore the fascinating world of rocks! Rocks are all around us, and they come in different shapes, sizes, and colors. They are an essential part of our planet Earth. Let's dive in and learn about the different types of rocks.

What are Rocks?

Rocks are solid materials that make up the Earth's crust. They can be found on mountains, in rivers, and even under the ground. Rocks are made up of different minerals and have different properties.

Types of Rocks

There are three main types of rocks: igneous, sedimentary, and metamorphic. Let's take a closer look at each of them.

Igneous Rocks
Igneous rocks are formed from molten lava or magma that cools and solidifies. When hot lava cools quickly, it forms rocks with tiny crystals. When it cools slowly, larger crystals form. Here are a few examples of igneous rocks:

• Granite: Granite is a hard rock that often has a speckled appearance due to its minerals. It is used to make kitchen countertops and buildings.
• Basalt: Basalt is a dark-colored rock that forms from lava cooling quickly. It can be found in volcanic areas and is used in construction and road building.

Sedimentary Rocks
Sedimentary rocks are formed by the accumulation of sediments over time. These sediments can be tiny pieces of other rocks, shells, or even plant and animal remains. Here are some examples of sedimentary rocks:

• Sandstone: Sandstone is made up of tiny grains of sand that have been compacted together. It is often used in building and as a paving material.
• Limestone: Limestone is formed from the remains of marine organisms like coral and shells. It is used to make cement and in construction.

Metamorphic Rocks
Metamorphic rocks are formed when existing rocks are subjected to high heat and pressure deep beneath the Earth's surface. This causes them to change and form new rocks. Some examples of metamorphic rocks are:

• Marble: Marble is a beautiful rock that forms from limestone. It is often used in sculptures and building materials.
• Slate: Slate is a smooth rock that can be easily split into thin layers. It is used for making roofs, blackboards, and billiard tables.

Fun Facts about Rocks

• Did you know that the Grand Canyon in the United States is made up of layers of sedimentary rocks?
• Some rocks, like pumice, can float on water because they are full of tiny air bubbles.
• Rocks can be different colors, including red, blue, green, and even rainbow colors!