Rock Types - SS1 Agriculture Lesson Note

There are three primary rock types, each with distinct characteristics and formation processes:

Igneous Rocks:

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Igneous rocks form from the solidification of molten material, either magma (beneath the Earth's surface) or lava (on the Earth's surface).

They can be classified into two categories based on where they form:

Intrusive Igneous Rocks: These form below the Earth's surface as magma cools slowly, allowing large crystals to develop. Examples include granite and diorite.

Extrusive Igneous Rocks: These form on the Earth's surface as lava cools rapidly, resulting in smaller or no visible crystals. Examples include basalt and pumice.

 

Sedimentary Rocks:

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Sedimentary rocks are created from the accumulation and compression of sediments, which can include mineral grains, organic material, and even the remains of plants and animals.

They often preserve evidence of past environments and can contain fossils.

Common examples include sandstone, limestone, and shale.

 

Metamorphic Rocks:

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Metamorphic rocks form from the alteration of existing rocks (igneous, sedimentary, or other metamorphic rocks) due to high temperature and pressure.

This process, called metamorphism, leads to the development of new minerals and textures while maintaining the original rock's parent material.

Examples of metamorphic rocks include marble (from limestone), schist (from shale or slate), and gneiss (from granite).

Understanding these rock types and their properties is essential for geologists to decipher Earth's history, study geological processes, and locate valuable resources like minerals and fossil fuels. It also plays a crucial role in fields such as construction, engineering, and environmental science.