The Classification of Rocks
- Earth's Crust = Made of Rocks:
The Earth's crust, that outer layer we talked about, is made up of lots of
different kinds of rocks.
- Rocks are Different:
Rocks are not all the same! They can be different in:
- Texture:
How they feel (rough, smooth, etc.).
- Structure:
How they are put together (layers, crystals, etc.).
- Color: Obvious!
- Permeability:
How easily water can pass through them (like a sponge or not).
- Mode of Occurrence:
How they are found in nature (layers, big masses, etc.).
- Resistance to Denudation:
How well they stand up to being worn away by weather and erosion.
- Why Study Rocks?
Important for:
- Geologists:
Scientists who study the Earth. They need to know rocks to understand:
- What the Earth is made of
(composition).
- How the Earth formed and changed over
time (physical history).
- Geographers:
People who study the Earth's surface and how we use it. They need to know
rocks to understand:
- How landforms are shaped (mountains,
valleys, etc.).
- Everyone!
We should know about rocks because:
- Rocks make soil:
Soil comes from broken down rocks.
- Soil affects plants:
Type of rock influences what plants can grow.
- Plants & Soil affect land use:
What we can do with the land (farming, building, etc.) depends on rocks
and soil.
- So, knowing rocks helps us understand
the world around us!
- Three Main Rock Types:
We can group all rocks into three main types based on how they are
made (origin) and what they look like (appearance):
- Igneous Rocks
- Sedimentary Rocks
- Metamorphic Rocks
In Simple Words: The
Earth's crust is rocky, but not all rocks are the same. They have different
properties that affect the land, soil, and even plants. Scientists study rocks
to understand the Earth. We can group all rocks into three main types: igneous,
sedimentary, and metamorphic, based on how they were formed.