13 terms

Agents of Weathering

Mechanical Weathering
The process that breaks rock into different shapes and smaller pieces. (physical appearance)
Heating and cooling that cause rocks to expand and contract. Temperature changes cause outer layers of rock to crack.
When the outer layers of rocks crack and break off
Frost Action
Liquid water seeps into cracks and expands when frozen, causing small cracks to widen and open up
ORganic Activity
Animals scratch and dig on the surface breaking rocks. Plant roots break up soil, even asphalt and concret
Gravity can pull loosened rocks down hills or mountains in a landslide. When mixed with water it is a mudslide
Wind carrying particles smooth rocks on the surface. Water carrying particles smooth rocks in rivers and oceans
Chemical Weathering
The process that changes the mineral composition or chemical make up of the rocks
Water can dissolve most types of minerals that hold rocks together. These rocks are said to be soluble which means able to dissolve
Oxygen chemically combines with other elements such as iron making iron oxide or rust
When carbon dioxide dissolves into water it is called carbonic acid. This can dissolve rocks but is too weak to harm people or plants. It can dissolve limestone and soft rocks.
Sulfuric Acid
Sulfur dioxide is a product of burning fossil fuels and it combines with water to form acid rain, which affects marble statues, paint, and metal
Plant Acids
Plants produce weak acids that break down rocks. Lichens or mosses break down rocks and can form soil.