Ch.7: Rocks and Rock Types

Rocks and Rock Types | Class 6 | Geography | Chapter 7 | Maharashtra State Board

In this video, viewers will learn about the fascinating world of rocks and their different types. The video provides an overview of three main types of rocks - Igneous Rocks / Primary Rocks, Sedimentary Rocks, and Metamorphic Rocks - and explores how they are formed and where they can be found. The video also delves into the topic of fossils and shares some interesting facts about rocks, such as how they are used in construction. Specifically, the video reveals which type of rocks were used to build iconic structures such as the Taj Mahal and Red Fort. This video is an excellent resource for those interested in geology or anyone looking to expand their knowledge about the world around them.

Questions & Answers

A. How is sand that flows in a river formed? Collect some information about where the sand comes from.

Ans. Whenever the river erodes, it erodes the rocks from the higher grounds. The river has immense energy to erode a bigger boulder. It erodes the bigger one and make it small, like pebble stones.

Further the river erode the pebbles to form sand and clay.

Most of the rocks and pebbles travels along with the water course where the sand and clay travels along with the water columns in a creamy form.

When the river loss its energy during the dry season the sand and clay gets sediment to the bottom on the river.

B. Which of the following monuments are built in igneous rock?

(1) The Taj Mahal

(2) Fort Raigad

(3) The Red Fort

(4) Ellora Sculpture

Ans. The Fort Raigad and the Ellora Sculpture are built in igneous rock.

C. Find the differences between.

1. Igneous and Sedimentary rocks.

Ans.

Igneous rocks	Sedimentary rocks
Igneous rocks are formed out of cooling down of magma and lava.	Sedimentary rocks are formed out deposition of layes of sediments and their compaction.
2. Igneous rocks are heavy.	2. Sedimentary rocks are lightweight.
Example: Granite, Basalt, Pumice.	Example: Sand stone, Lime stone, Shale.

2. Sedimentary and Metamorphic rocks

Ans.

Sedimentary rocks	Metamorphic rocks
Sedimentary rocks are formed out of deposition of layers of sediments and their compaction.	Metamorphic rocks are formed out of re-crystallization of the original rocks due to tremendous heat and pressure.
2. Sedimentary rocks are lightweight.	2. Metamorphic rocks are heavy.
Example: Sand stone, Lime stone, Shale	Example: Slate, Marble, Quartzite.

3. Igneous and Metamorphic rocks

Ans.

Igneous rocks	Metamorphic rocks
Igneous rocks are formed out of cooling down of magma and lava.	Metamorphic rocks are formed out of re-crystallization of the original rocks due to tremendous heat and pressure.
2. Igneous rocks are referred to as primary rocks.	2. Metamorphic rocks are not referred to as primary rocks.
Example: Granite, Basalt, Pumice	Example: Slate, Marble, Quartzite

D. Which types of rocks are predominantly found at the following locations ?

(1) Central Maharashtra

(2) South Konkan

(3) Vidarbha

Ans. Types of rocks are predominantly found at the following locations.

1. Central Maharashtra: Basalt rock

2. South Konkan: Laterite

3. Vidarbha: Granite

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E X T R A

A. Fill in the blanks with right alternative.

1. Basalt and Pumice are examples of Igneous rocks.

2. Sedimentary rocks are generally brittle and lightweight.

3. Coal gets metamorphosed when it undergoes heavy pressure and intense heat.

4. Marble is a metamorphic rock.

B. Answer in one sentence.

1. What is rock?

Ans. Rock is a mixture of different minerals formed by natural processes in the lithosphere.

2. Name the different types of rocks?

Ans. a) Igneous rocks/ primary rocks.

b) Sedimentary rocks.

c) Metamorphic rocks.

C. Answer in Brief.

1. What are igneous rocks? Explain main features of igneous rocks ?

Ans. When the molten material, known as magma within the crust and lava on the surface cools down it solidifies giving rise to rocks, these are known as igneous rocks.

1. As these rocks are formed out of the material from the interior of the earth, these are also referred to as primary rocks.

2. Mostly these rocks appear hard and homogeneous.

3. These are heavy as well.

4. We do not get fossils in these rocks.

D. Explain in Brief.

1. The distribution of major rocks in Maharashtra.

Ans.

1. Basalt rock formed out of volcanic eruption has spread over a vast region of Maharashtra state.

2. Granite rock is found in the eastern parts in South Konkan.

3. Laterite rock is found in South Konkan.

2. The formation of sedimentary rocks. Give examples.

Ans.

1. Weathered rock particles get transported by rivers, glaciers, wind etc. towards low lying areas and are deposited there.

2. One after the other, layers of sediments get deposited in this way.

3. The upper layers exert heavy pressure on the lower layers. This leads to compaction of material and development of sedimentary rocks.

4. Example: Sandstone and Limestone.

E. Give Reasons.

1. Mining activity is concentrated in South Konkan and eastern Maharashtra.

Ans. Because of thick and extensive layers of basalt, Maharashtra does not have large reserves of mineral wealth. Therefore, mining activity is concentrated in South Konkan and in eastern Maharashtra, which has rocks like granite.

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