By Dr. Bryan Rithesh Miranda
Rocks are the foundation of Earth’s crust, formed over millions of years through natural processes. Understanding how rocks are made can help us appreciate their importance in everyday life, from the buildings we live in to the tools we use.
The Three Types of Rocks
Rocks are classified into three main types based on their formation process:
Igneous Rocks
Formation: These rocks form when molten magma or lava cools and solidifies.
Intrusive igneous rocks (e.g., granite) cool slowly beneath the surface, resulting in larger crystals.
Extrusive igneous rocks (e.g., basalt) cool quickly on the surface, forming smaller crystals.
Uses:
o Granite is used in countertops and construction.
o Basalt is a key material in road construction.
Sedimentary Rocks
Formation: These rocks form from layers of sediment—small particles of sand, silt, and organic material—compressed over time.
Common examples include limestone and sandstone.
Uses:
o Limestone is used to make cement and as a building material.
o Sandstone is used in decorative and structural construction.
Metamorphic Rocks
Formation: These rocks form when existing rocks (igneous, sedimentary, or other metamorphic rocks) are exposed to high pressure and temperature, altering their structure. Examples include marble and slate.
Uses:
Marble is prized for statues and flooring due to its aesthetic appeal.
Slate is used for roofing and flooring.
The Rock Cycle
Rocks do not stay the same forever. Through a continuous process called the rock cycle, rocks transform between types:
Igneous to Sedimentary: Erosion breaks down igneous rocks into sediments, which later form sedimentary rocks.
Sedimentary to Metamorphic: Under pressure and heat, sedimentary rocks become metamorphic rocks.
Metamorphic to Igneous: When metamorphic rocks melt into magma and cool again, they form igneous rocks.
Why Rocks Matter
Rocks are essential to human civilisation. They provide:
Construction materials: Cement, bricks, and tiles.
Industrial uses: Metals like iron and copper are extracted from rocks.
Energy resources: Fossil fuels, like coal and oil, are stored in sedimentary rocks.
Rocks are more than just pieces of Earth—they tell stories of millions of years of geological history. By understanding their formation, types, and uses, we can better appreciate their role in shaping our world.
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