Landforms

• External

  • Erosion: wearing away of the Earth’s surface due to wind, rain, and water

  • Rock Weathering

    • When rocks break apart and decay

    • 3 types:

      • Chemical

      • Breaking

      • Forceful

      • First step in soil formation

Chemical weathering

• Pollution in the atmosphere

  • Acid rain

• East coast has the most amount of acid rain

  • Plant and animal life struggle to survive

Breaking

• Tree roots

• Ice in cracks

  • forces rock to expand and break apart

Forceful

• Wind blowing sediment against rocks

• Sand blaster

  • Compressed air pushes against rock to reduce rust/erode

Glaciers

• Sheet glaciers - covers large masses of ice

  • Greenland and Antarctica

• Large amounts of land

• Ice ages

Examples of Erosion

• Mountain Glaciers

  • Compared to sheet glaciers these are smaller and more common

  • Mostly found in Alaska (NA)

  • Created by elevation

  • For every 100ft of snow = 1ft of glacial ice

  • Ice fields - gigantic areas of ice that feed the different glaciers

  • worms/grass

• Wind Erosion

  • Wears down surface and transports sediment

  • Areas with no vegetation - most prevalent

  • Beaches, deserts, open fields

• Water Deposition

  • Sediments transported and deposited by streams, rivers, lakes, and oceans

  • The Grand Canyon keeps getting deeper as the colorado river is present due to water erosion

  • Erodes and transports

  • Canyons, valleys, gullies

Secondary Landforms

• Created from the erosion of the primary landforms

• Erosion, weathering, water wind

Alluvial Fan

• Sediments deposited by water at the base of a mountain as it enters a plain

  • Rocky Mountains

Flood Plain

• Sediment deposited by a river prone to flooding

Delta

• Sediment deposited by a river as it enters an ocean

• Mississippi

• Amazon

Canyons

• Deep grooves in the Earth’s surface

• Caused by water and glaciers

Internal Activities 

• Changes the surface of the Earth by building up the surface

• Creates primary landforms

• 2 sources: heat and plate movements

• Heat: 12,000 F at center, heat currents melt upper parts if mantle

• Magma: melted rock found below the surface

• Lava: magma reaches the surface of the Earth

• Volcanoes: mountains of lava

• Plate movements: Plate tectonics

• Folds: when rock layers move and bend

  • Small mountains, hills, creases

• Faults: rock layers move and break

  • Can be caused by Earthquakes

Plate Tectonics

• Theory that the Earth is made of rigid, moving plates

• 7 major plates = continents

• Several smaller plates = ocean floors

Pangea

• Supercontinent

3 plate boundaries

• Describe movements along plate edges

• Convergent Boundaries

  • 2 plates collide

  • 2 ocean plates

    • Also called subduction zones

    • Where we have trenches on the ocean floors

    • 1 plate is smaller and is pushed under a large plate creating a trench

    • Largest trench is Mariana Trench

  • 2 continental plates

    • Smaller in size

    • Plate edges are forced upwards

    • Forms mountain ranges

• Transform Fault/movement

  • 2 plates slide pass each other

  • Energy is released from deep within the Earth

  • Earthquakes cause this

• Divergent Boundary

  • Known as sea floor spreading

  • Melting rocks fill opening

  • Creates new ocean floors

  • Ridges

  • Volcanoes

  • Mid Atlantic Ridge is the largest ridge on the planet

Primary Landforms

Described as large land masses created by uplifting forces

Plate tectonics and heat

• Volcanoes

• Mountains

• Trenches

• Bridges

• Plateaus

• islands

• Relief - distance between highest and lowest point in elevation

  • More relief in appalacians due to them being steeper