[Q2] EarthSci - Endogenic Processes

• Endogenic Process - processes that is formed or occurring beneath the surface of the Earth
• Endogenic Forces - the forces within the Earth that cause the ground to move
• Main Endogenic Processes

  • Folding
  • Faulting
• Tectonic Movements (Folding and Faulting) take place mainly along the plate boundaries, which are the zones that are not stable.
• Folding - when two forces push towards each other from opposite sides; process by which folds are formed due to compressional forces
• Anticlines - folded rock formations that have an upwards convex shape
• Syncline - fold that arches downward to form a trough
• Anticlines and Synclines are usually made up of many rock units that are folded in the same pattern.
• Faulting - fracturing and displacement of more brittle rock strata along a fault plane either caused by tension or compression
• Fault - a break in rock along which a vertical or horizontal rock movement has occurred
• Faulting - process of forming a fault
• Fault Line - line of fault which appears on land surface; often lines of weakness that allows molten rock to rise up onto the Earth's surface when there is active volcanic activity nearby
• Types of Faults

  • Normal
  • Reverse
  • Tear
  • Rift Valley
  • Horst
• Normal Fault - when rocks move away from each other due to the land moving apart
• Reverse Fault - opposite of normal faults; rocks are compressed such that one plate moves up while the other descends below it
• Tear Fault - also known as a transform fault; when two tectonic plates slide in a lateral motion past each other; causes most severe earthquakes
• Rift Valley - when two normal faults occur parallel to each other and the land sinks between the faults
• Horst Fault - opposite of a rift valley; land between the parallel faults is forced upward because the two faults are being pushed together
• Other Endogenic Processes (Subsequent)

  • Volcanism (Volcanic Activity)
  • Metamorphism
  • Earthquake (Seismic Activity)
• Volcanism - magmatism (also known as volcanic activity or igneous activity); magma beneath the crust is under very great pressure
• Intrusive Volcanism - when magma is forced into the rocks that make up the Earth's crust; when it cools and become solid while still underground, different features called plutons are formed, rock formed is intrusive igneous rock
• Intrusive Rocks - form inside the Earth
• Extrusive Volcanism - volcanic activity that takes place above ground; on the exterior, outside of the Earth
• Result of Volcanism

  • Basalt
  • Andesite
  • Scoria
  • Obsidian
• Metamorphism - endogenic process which occurs when there is pressure and heat applied to geologic structures leading to the formation of metamorphic rocks
• Result of Metamorphism

  • Marble
  • Amphibolite
  • Slate
  • Schist
• Earthquake - seismic activity; sudden shaking or vibration in the Earth's crust
• Radioactive Decay - when these decay, they give off heat; keeps heat generation inside the Earth
• Magma - mixture of molten rock, suspended mineral grains, and dissolved gases that fuels all volcanoes
• Factors that effect Magma Formation

  • Temperature
  • Pressure
  • Water Content
  • Mineral Composition
• • Increasing pressure raises the melting point
  • Increasing water content lowers the melting point
• Center Temperature of the Planet - 5000 - 7000 °C
• Temperature where it is high enough to melt the rocks involved - 1400 - 2100 °F
• The asthenosphere which is between 100 to 350 km deep is so hot that most of the rock is melted.
• In the laboratory, most rocks melt between 800 - 1200 °C.
• Strain - when rocks deform they are said to this; a change in size, shape, or volume of a material
• Stress - forces acting on rock; force applied on a rock per unit area
• Types of Stress

  • Tensional
  • Compressional
  • Shear
• Tensional Stress - act in opposite directions, pulling rock apart or stretching it
• Compressional Stress - act toward each other, pushing or squeezing rock together