Geology Chapter: Lithosphere and Plate Tectonics

Lithosphere and Geological Processes

Plate Tectonics

• The lithosphere is broken into several large plates that float on the more fluid asthenosphere
• These plates move relative to each other, resulting in geological processes such as:
  • Seafloor spreading: creation of new oceanic crust at mid-ocean ridges
  • Continental drift: movement of continents relative to each other
  • Subduction: sinking of dense oceanic crust into the mantle at trenches

Volcanic Activity

• Volcanic activity occurs at the boundaries of tectonic plates, resulting in:
  • Volcanic arcs: formation of volcanic chains at subduction zones
  • Hotspots: volcanic activity at fixed points, creating volcanic chains as the plate moves
  • Flood basalts: large-scale volcanic eruptions that cover extensive areas

Earthquakes

• Earthquakes occur when there is a sudden release of energy as a result of:
  • Plate movement at faults, resulting in seismic waves
  • Stresses building up at plate boundaries, causing earthquakes
  • Volcanic activity, resulting in volcanic earthquakes

Mountain Building

• The process of mountain building occurs when:
  • Two plates collide, resulting in the formation of mountains (e.g. Himalayas)
  • The Earth's crust is thickened and deformed, resulting in the formation of fold mountains
  • Volcanic arcs collide with continents, resulting in the formation of mountain ranges

Weathering and Erosion

• The lithosphere is constantly being shaped by:
  • Weathering: breakdown of rocks into smaller particles through chemical and physical processes
  • Erosion: removal of weathered rocks through wind, water, and ice

Lithosphere and Geological Processes

Plate Tectonics

• Lithosphere is broken into several large plates that float on the more fluid asthenosphere
• Plate movement results in geological processes such as seafloor spreading, continental drift, and subduction
• Seafloor spreading creates new oceanic crust at mid-ocean ridges
• Continental drift involves the movement of continents relative to each other
• Subduction involves the sinking of dense oceanic crust into the mantle at trenches

Volcanic Activity

• Volcanic activity occurs at plate boundaries, resulting in volcanic arcs, hotspots, and flood basalts
• Volcanic arcs form at subduction zones
• Hotspots are fixed points of volcanic activity, creating volcanic chains as the plate moves
• Flood basalts are large-scale volcanic eruptions that cover extensive areas

Earthquakes

• Earthquakes occur due to sudden release of energy from plate movement at faults or stresses building up at plate boundaries
• Seismic waves are generated by plate movement at faults
• Volcanic activity can also result in earthquakes

Mountain Building

• Mountain building occurs through plate collision, resulting in formation of mountains (e.g. Himalayas)
• Thickening and deformation of the Earth's crust forms fold mountains
• Volcanic arcs colliding with continents form mountain ranges

Weathering and Erosion

• Weathering breaks down rocks into smaller particles through chemical and physical processes
• Erosion removes weathered rocks through wind, water, and ice
• Weathering and erosion shape the lithosphere continuously