internal forces that shape the earth (plate actions)
TRANSCRIPT
Internal Forces that Shape the Earth (Plate Actions)
Plate Tectonics
• Continental Drift – plates move slowly across upper mantle
• “Pangaea” – supercontinent existed 250 million years ago
Divergent Boundary• Plates separate / spread apart
A. Mid ocean ridge• Two ocean plates separate
B. Rift Valley
• Two land plates separate
Convergent Boundaries• Plates collide
A. Mountains• Two land plates collide
B. Island Chains
• Two ocean plates collide
C. Ocean Trench and Mountains
• Land and ocean plates collide
Transform Boundary
• Two plates slide against each other
A. Fault
V. Earthquakes and volcanoes form along plate boundaries
External Forces that Shape the Earth
Weathering• The breaking down of rock into sediment
Physical Weathering
Chemical Weathering
Erosion
• The carrying away
of sediment
A. Water is the greatest agent of erosion
B. Wind
C. Glaciers / Ice
Landforms
1. Created by tectonic processes1. Mountains, valleys
2. Created by erosion1. Plateau, plains
3. Created by sediment deposition1. Sand dune, floodplain
Most regions have a combination of all three types
Example:
Mountain range formed by tectonic activity.
Erosion forms deep valleys between the mountains.
Sediment eroded from the mountains is deposited at the mountains’ bases.
Creates an alluvial fan.
Alluvial fan: fan-shaped deposit of mud and gravel often found at the base of mountains.
Stream erodes the sediment in the alluvial fan and carries them to a river mouth.
Sediment moves into the ocean and sinks, or it may accumulate and build a delta.