1. Weathering, Erosion, and Deposition

2. Weathering, Erosion, and Deposition
Weathering, erosion, and deposition are processes that act together to wear down and build up Earth’s surface. These processes have occurred for billions of years.

3. Weathering
Weathering: Any process that breaks down rocks and creates sediment.
Weathering acts slowly, but over time can break down large portions of rock.
There are two forms of weathering-chemical and mechanical (physical).

4. Chemical vs. Mechanical Weathering
Mechanical- also known as physical weathering, occurs when rock is physically broken down into smaller pieces.
Chemical-occurs when rock is broken down through chemical changes.

5. Mechanical Weathering
Freezing and Thawing
When water seeps into cracks then expands as it freezes making the crack bigger. As the water thaws, the cycle repeats itself.
Animals
Animals can break rock and ground up as they burrow/move.
Plant Growth
Roots of trees and other plants can grow between cracks in rock and move them apart.
Abrasion
When other rock particles grind and smooth other rock surfaces like sandpaper.

6. Chemical Weathering Water Oxygen Carbon Dioxide Living Organisms
Dissolves minerals in the rock as it is broken down into smaller pieces.
Oxygen
Rocks that contain iron (Fe) will oxidize (rust) from oxygen in the air.
Carbon Dioxide
Carbon dioxide mixes with water to make carbonic acid. This will dissolve certain rocks like marble and limestone.
Living Organisms
Plants produce weak acid that can slowly dissolve rock around its roots.
Acid Rain
The burning of fossil fuels for energy produces compounds that chemically react with the air to produce acid rain.

7. Factors that determine the rate of weathering…
Climate/Environment
Chemical Weathering happens faster in warm and wet climates
Mechanical weathering happens faster when temperatures change on a regular basis (freezing/thawing)
Type of Rock
Some minerals in the rock dissolve faster than others

8. Examples of Weathering
Mechanical Weathering
Chemical Weathering

9. Erosion
Erosion-process by which natural forces move weathered rock and soil from one place to another.
Gravity
Moving water
Wind
Ice (glaciers)

10. Factors that determine the rate of erosion…
Topography/Vegetation
How steep the elevation is and how covered it is with vegetation.
Weather
Type of Rock
Climate
Speed of water or wind

11. Deposition
Deposition: happens when agents of erosion (example wind or water) lay down or ‘deposit’ sediment.

12. Pulling it all together…
Weathering, erosion, and deposition are at work everywhere, all the time, on Earth.
Gravity pulls everything toward the center of Earth causing rock and other material to move downhill.
Water’s movement (both on land and underground) cause weathering and erosion, which change the land’s surface features and create underground formations.

13. Pulling it all together…
Some of the effects of those processes include:
Changes in shape, size, and texture of landforms (mountains, riverbeds, and beaches).
Landslides
Buildings, statues, and roads wearing away
Soil formation
Washes soil, pollutants, harmful sediments into water ways.
Causes metal to rust
Reduces beaches and shorelines
Forms new landforms (stalactites and stalagmites)