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What is/are the difference(s) between extrusive and intrusive rocks?
1. Extrusive rocks are formed from magma, whereas intrusive rocks are formed from lava.
2. Extrusive rocks arc fine-grained, whereas intrusive rocks arc coarse-grained.
3. Extrusive rocks form over a much longer duration of time compared to intrusive rocks.
Select the correct answer using the codes below:
  • a)
    2 only
  • b)
    1 and 3 only
  • c)
    3 only
  • d)
    1 only
Correct answer is option 'A'. Can you explain this answer?
Most Upvoted Answer
What is/are the difference(s) between extrusive and intrusive rocks? ...
Difference between Extrusive and Intrusive Rocks

Introduction
Extrusive and intrusive rocks are two types of igneous rocks that differ in their formation, texture, and the duration of their formation. Understanding these differences is important in the study of geology and helps in identifying and classifying various rock formations.

Formation
1. Extrusive Rocks: Extrusive rocks are formed from magma, which is molten rock that reaches the Earth's surface through volcanic activity. When magma erupts from a volcano, it cools rapidly and solidifies to form extrusive rocks. Examples of extrusive rocks include basalt, obsidian, and pumice.

2. Intrusive Rocks: Intrusive rocks, on the other hand, are formed from lava, which is magma that has reached the Earth's surface. Instead of erupting, lava flows out of the volcano and cools slowly beneath the surface. This slow cooling allows for the formation of large mineral crystals, resulting in coarse-grained textures. Examples of intrusive rocks include granite, gabbro, and diorite.

Texture
1. Extrusive Rocks: Extrusive rocks have a fine-grained texture due to their rapid cooling. As the magma cools quickly at the surface, there is insufficient time for large mineral crystals to form. Instead, small crystals or even glassy structures are observed in extrusive rocks.

2. Intrusive Rocks: Intrusive rocks have a coarse-grained texture because of their slow cooling process. As the magma cools slowly beneath the surface, there is ample time for large mineral crystals to develop. These crystals are often visible to the naked eye and contribute to the coarse-grained appearance of intrusive rocks.

Duration of Formation
1. Extrusive Rocks: Extrusive rocks are formed relatively quickly, as the magma reaches the surface and cools rapidly. This process typically takes place over a short duration of time, such as days or weeks.

2. Intrusive Rocks: In contrast, the formation of intrusive rocks occurs over a much longer duration of time. The slow cooling of lava beneath the surface can take thousands or even millions of years, allowing for the growth of large mineral crystals.

Conclusion
In summary, extrusive and intrusive rocks differ in their formation, texture, and the duration of their formation. Extrusive rocks are formed from magma, have a fine-grained texture, and are formed relatively quickly. In contrast, intrusive rocks are formed from lava, have a coarse-grained texture, and are formed over a longer duration of time. Understanding these differences is essential in the study of igneous rocks and helps in identifying and classifying various geological formations.
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Community Answer
What is/are the difference(s) between extrusive and intrusive rocks? ...
  • The key difference between intrusive and extrusive rocks is that the intrusive rocks are formed from magma whereas the extrusive rocks are formed from lava. Rest of the differences follow from the basic structure.
Intrusive rocks: With no air to cool the magma, these rocks are formed very slowly Composition of these rocks reflects the presence of large crystals. These crystals interlock to form the rock. These rocks take a very large amount of time to solidify and they remain buried deep inside the surface of the Earth being surrounded by country rocks that have been there already.
Extrusive rocks: Sometimes, molten rocks find a way to come out of the surface of the Earth through cracks and openings. This magma flows in the form of lava and cools down quickly as it comes into contact with air. Igneous rocks that are formed from the magma that pours out of the surface of the Earth arc called extrusive rocks. As these rocks cool down and solidify very quickly, they do not get sufficient time to form target crystals. Thus, they have small crystals and boast a fine texture.
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What is/are the difference(s) between extrusive and intrusive rocks? 1. Extrusive rocks are formed from magma, whereas intrusive rocks are formed from lava.2. Extrusive rocks arc fine-grained, whereas intrusive rocks arc coarse-grained.3. Extrusive rocks form over a much longer duration of time compared to intrusive rocks.Select the correct answer using the codes below: a) 2 onlyb) 1 and 3 onlyc) 3 onlyd) 1 onlyCorrect answer is option 'A'. Can you explain this answer?
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What is/are the difference(s) between extrusive and intrusive rocks? 1. Extrusive rocks are formed from magma, whereas intrusive rocks are formed from lava.2. Extrusive rocks arc fine-grained, whereas intrusive rocks arc coarse-grained.3. Extrusive rocks form over a much longer duration of time compared to intrusive rocks.Select the correct answer using the codes below: a) 2 onlyb) 1 and 3 onlyc) 3 onlyd) 1 onlyCorrect answer is option 'A'. Can you explain this answer? for UPSC 2024 is part of UPSC preparation. The Question and answers have been prepared according to the UPSC exam syllabus. Information about What is/are the difference(s) between extrusive and intrusive rocks? 1. Extrusive rocks are formed from magma, whereas intrusive rocks are formed from lava.2. Extrusive rocks arc fine-grained, whereas intrusive rocks arc coarse-grained.3. Extrusive rocks form over a much longer duration of time compared to intrusive rocks.Select the correct answer using the codes below: a) 2 onlyb) 1 and 3 onlyc) 3 onlyd) 1 onlyCorrect answer is option 'A'. Can you explain this answer? covers all topics & solutions for UPSC 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for What is/are the difference(s) between extrusive and intrusive rocks? 1. Extrusive rocks are formed from magma, whereas intrusive rocks are formed from lava.2. Extrusive rocks arc fine-grained, whereas intrusive rocks arc coarse-grained.3. Extrusive rocks form over a much longer duration of time compared to intrusive rocks.Select the correct answer using the codes below: a) 2 onlyb) 1 and 3 onlyc) 3 onlyd) 1 onlyCorrect answer is option 'A'. Can you explain this answer?.
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