1. Constructive and Destructive Landforms

2. Two Types of Forces
Destructive Forces: processes that destroy landforms.
2 types: Slow (weathering) and Fast (Erosion)
Ex. landslides, volcanic eruptions, earthquakes, floods
Constructive forces: forces that build up an existing landform or create a new one.
Caused by: water, gravity, wind and glaciers.
Ex: deposition, landslides, volcanic eruptions, floods

3. Weathering
Weathering is the breaking down of rocks into smaller pieces.
Rain, ice, and atmospheric gases cause this.

4. Physical/ Mechanical weathering
Rocks are broken into smaller pieces by physical agents.
Ice wedging.
Plant and animal actions.
Water

5. Chemical weathering
Breaking down of rocks due to the chemical change in their composition.
Air and water often cause this.
Oxidation (rust) and acid rain.

6. Erosion
The process that moves rock material at Earth’s surface and caries it away.
Movement of the rock particles.

7. Causes of erosion… Gravity-landslides/rockslides.
Running water-rivers form canyons
Groundwater-underground water forms caves/caverns
Glaciers-rocks are carried under a glacier.
Wind-rock particles are blown
Ocean currents-sand is moved along a beach by waves.

9. Constructive Landform Processes
Processes that build up Earth’s surface and cause the land surface to rise.

10. Deposition
The process by which eroded material is dropped off or deposited in a new area.
Gravity
Water
Wind
Glaciers
Ocean currents

11. Volcanic Eruptions Volcano: ???
an opening in the Earth’s crust through which steam, lava and ashes erupt.
Cause both destructive and constructive changes to landforms.

12. Volcanoes can be constructive, but also destructive…

13. Folding and Faulting
Forces in Earth’s surface caused by the movement of Earth’s plates squeezes and bends the surface of Earth.
Folding occurs when the crust is bent upward or downward.
Faulting occurs when the crust is actually broken.

14. Volcanic Activity
The movement of liquid rock underground and on earth’s surface.
Magma is hot liquid rock beneath the Earth’s surface.
Magma is less dense than solid rock so it rises to the surface.
This forms a volcano.

15. When volcano’s erupt, they release hot liquid rock called lava.
Lava will harden forming new landforms.

16. Mount St. Helens
Saint Helen’s Before
Saint Helen’s After

17. Earthquakes
Earthquakes: the shaking of Earth’s surface caused by the release of energy along a fault.
San Andreas Fault, California

18. Volcanoes & Earthquakes
Tectonic Plates, Volcanoes & Earthquakes

19. Landforms from Erosion
Canyons/valleys
Flowing water removes sediment.

20. Sea cliffs
Waves erode rock making steep cliffs.

21. Sea caves, arches, and stacks.

22. Landforms from Deposition
Flood plains
Sediments deposited when rivers overflow their banks.

23. Deltas and Alluvial Fans
When a stream flows into a large body of water (lake/ocean) or onto land, it deposits sediment in a fan shape.
Delta-fan shaped pattern in a lake or ocean.
Alluvial fan-fan shaped pattern on land.

25. Water Erosion & Deposition
River Delta- Deposits of sediment at the mouth of the Mississippi River creating new land called a delta.

26. Beaches
Area of shoreline made up of sediment deposited by ocean currents and waves.

27. Landforms from Folding and Faulting
Block mountains
Large areas of Earth are forced upwards in a fault.

28. Rift valley
When two pieces of Earth’s surface are separating from each other.

30. Folded mountains
When the surface of Earth is bent upward making a mountain.

31. Landforms from Volcanic Activity
Volcanoes

32. Dome mountain
Magma forces the surface of Earth up into a dome shaped mountain.

33. Plateau

34. Primetime What are two examples of destructive forces?
What are four examples of constructive forces?
Give an example where constructive and destructive forces work together to create a landform.