Unit 4 Notes
4.1-Plate Tectonics
Plate boundaries - Earth is made of layers;
➢ Lithosphere (crust)
➢ Asthenosphere (upper mantle)
➢ Mesosphere (lower mantle)
➢ Plates are the less dense upper part of the crust floating on the denser lower portion
Convergent Plate Boundary
➢ Plates push towards each other
➢ Typically causes volcanoes
➢ Releases magma
➢ May cause earthquakes
Divergent Plate Boundary
➢ Plates push away from each other
➢ May have ridges or volcanoes
➢ Typically causes seafloor spreading
➢ May cause less frequent earthquakes
Transform Plate Boundary
➢ Plates push/slide past each other
➢ No ridges of volcanoes
➢ Shallow, more frequent earthquakes
Where Are The Plate Boundaries?
➢ Plates are moving in all directions
➢ Each plate may have all 3 different plate boundaries
➢ Movement of the plates can determine geological features at the boundary
➢ Type of plate, continental/oceanic, plays a factor
Convergent + Divergent Boundaries
➢ Continental plates are less dense, so "float" higher
➢ Leads to:
○ Volcanoes
○ Island arcs
○ Earthquakes
○ Hot spots
○ Faults
Earthquake Formation
➢ Occur at plate boundaries/fault lines.
➢ Fault lines lock up-building up stress-energy
➢ Energy releases, causing an earthquake
, Unit 4 Notes
Tectonic Plate Consequences
➢ Plates can have breaks in their surface, leading to volcanic island chains
○ Japan, Indonesia, Hawaii
Tsunamis
➢ Earthquakes →Tsunamis
➢ Tsunami: long sea wave, can also be caused by underwater landslides
➢ Ecological consequences
○ Destroys habitats
○ Drowns species
○ Uproots trees
○ Contaminates water with saltwater/debris
4.2-Soil Formation and Erosion
Soil Formation
Soil is formed when parent material is weathered, transported, and deposited
Parent material: Original rocks that were broken down to form the basis of the soil
Weathering: Mechanical breakdown of rock
Factors in Soil Formation
➢ Type of parent material- rocks are broken down by wind and rain; soil tends to retain
basic chemistry of these rocks
➢ Climate - average temperature and moisture change rate of weathering and leaching
(nutrients in water), wind redistribution
➢ Topography- slope of the land may affect erosion
➢ Biological factors- plants, animals, microorganisms
➢ Time- soil formation is continuous, there's no end
Soil Profile (Soil Horizons)
O-Horizon: Organic layer
A Horizon: Topsoil- most fertile layer
E-Horizon: Nutrient leaching
B-Horizon. Subsoil
C- Horizon: Parent material (Substrate)
B-Horizon: Bedrock
Soil Erosion
Soil erodes due to several factors
➢ Water
4.1-Plate Tectonics
Plate boundaries - Earth is made of layers;
➢ Lithosphere (crust)
➢ Asthenosphere (upper mantle)
➢ Mesosphere (lower mantle)
➢ Plates are the less dense upper part of the crust floating on the denser lower portion
Convergent Plate Boundary
➢ Plates push towards each other
➢ Typically causes volcanoes
➢ Releases magma
➢ May cause earthquakes
Divergent Plate Boundary
➢ Plates push away from each other
➢ May have ridges or volcanoes
➢ Typically causes seafloor spreading
➢ May cause less frequent earthquakes
Transform Plate Boundary
➢ Plates push/slide past each other
➢ No ridges of volcanoes
➢ Shallow, more frequent earthquakes
Where Are The Plate Boundaries?
➢ Plates are moving in all directions
➢ Each plate may have all 3 different plate boundaries
➢ Movement of the plates can determine geological features at the boundary
➢ Type of plate, continental/oceanic, plays a factor
Convergent + Divergent Boundaries
➢ Continental plates are less dense, so "float" higher
➢ Leads to:
○ Volcanoes
○ Island arcs
○ Earthquakes
○ Hot spots
○ Faults
Earthquake Formation
➢ Occur at plate boundaries/fault lines.
➢ Fault lines lock up-building up stress-energy
➢ Energy releases, causing an earthquake
, Unit 4 Notes
Tectonic Plate Consequences
➢ Plates can have breaks in their surface, leading to volcanic island chains
○ Japan, Indonesia, Hawaii
Tsunamis
➢ Earthquakes →Tsunamis
➢ Tsunami: long sea wave, can also be caused by underwater landslides
➢ Ecological consequences
○ Destroys habitats
○ Drowns species
○ Uproots trees
○ Contaminates water with saltwater/debris
4.2-Soil Formation and Erosion
Soil Formation
Soil is formed when parent material is weathered, transported, and deposited
Parent material: Original rocks that were broken down to form the basis of the soil
Weathering: Mechanical breakdown of rock
Factors in Soil Formation
➢ Type of parent material- rocks are broken down by wind and rain; soil tends to retain
basic chemistry of these rocks
➢ Climate - average temperature and moisture change rate of weathering and leaching
(nutrients in water), wind redistribution
➢ Topography- slope of the land may affect erosion
➢ Biological factors- plants, animals, microorganisms
➢ Time- soil formation is continuous, there's no end
Soil Profile (Soil Horizons)
O-Horizon: Organic layer
A Horizon: Topsoil- most fertile layer
E-Horizon: Nutrient leaching
B-Horizon. Subsoil
C- Horizon: Parent material (Substrate)
B-Horizon: Bedrock
Soil Erosion
Soil erodes due to several factors
➢ Water
