1. Unit G1- Environmental Chemistry Rocks & Soils
Form Group 3G
27th November 2006

2. What is a Rock?
A rock is a naturally occurring aggregate of minerals. They are classified by mineral and chemical composition, by the texture of the constituent particles and by the processes that formed them.

3. Types of Rocks

5. Rock Types Type Examples Characteristics Sedimentary Sandstone
Limestone
Grainy and Crubly. They may contain fossils.
Metamorphic
Slate
Marble
-Small crystals in layers (or bands).
Hard and smooth.
Igneous
Basalt
Granite
-Small crystals due to fast cooling. Hard rocks.
-Large crystals due to slow cooling. Hard rocks.

6. Weathering?
Process of disintegration of rocks, soils and their minerals through direct, or indirect contact with the atmosphere.
Physical
Biological
Chemical

7. Physical Weathering Effect of the sun
During the day the rocks are warmed up and expand while...
...at night they cool down and contract.
Rocks cracking and eventually breaking up.
Effect of freezing water
Any water which gets into cracks in rocks will expand when it freezes.
Cracks will get bigger and bigger...
The rock will break up into smaller pieces

8. Chemical Weathering e.g. Acid Rain Due to chemical reactions between
substances in the rock and
acidic rainwater.
e.g. Acid Rain

9. Biological Weathering
Due to the actions of plants and animals.

10. About Soils... 6 different components: 1 – Rock Particles
Soils forms when the rocks are physically and chemically weathered over the years.
6 different components:
1 – Rock Particles
2 – Mineral Salts
3 – Humus
4 – Water
5 – Air
6 – Living organisms

11. Soil Types
Sandy
2. Clay
3. Loam or Silt