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Life Cycle of Volcanoes

Life Cycle of Volcanoes. Active Volcano. Erupting now Has erupted in the recent past Shows signs of erupting in the near future. Dormant Volcano. Volcano that has not erupted recently But has in recorded history It is expected to erupt again. Extinct Volcano.

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Life Cycle of Volcanoes

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  1. Life Cycle of Volcanoes

  2. Active Volcano • Erupting now • Has erupted in the recent past • Shows signs of erupting in the near future

  3. Dormant Volcano • Volcano that has not erupted recently • But has in recorded history • It is expected to erupt again

  4. Extinct Volcano • Has not erupted in recorded history • Is not expected to erupt again

  5. Volcanism Underground(subterranean)

  6. Igneous Intrusions • Flows of magma that cool and harden before they reach the surface • Intrusive rocks have a large grain or crystal size • The deeper the intrusion, the larger the crystal

  7. Volcanic Neck • Intrusive structure composed of cooled magma trapped in the vent or throat of a volcano

  8. Devil’s Tower, WY

  9. Steamboat Springs, CO

  10. Ship Rock, NM

  11. Dike • A tabular, mostly vertical intrusion • Vertical structures are called “DISCORDANT” in geology • Depth of intrusion determines the grain size • Dikes are often more resistant to erosion than surrounding rock; leave a dam-like structure on surface • There are ancient dikes in Wisconsin

  12. Ship Rock, NM Dike

  13. Dike in Alaska

  14. Sill • Relatively horizontal structure that is parallel to rock layers • Parallel w/ layers is called “CONCORDANT” in geology • Magma squeezes between layers and solidifies into a sill • Grain size is dependent on depth it is formed

  15. Purcell Sill, Montana Limestone Sill Diorite Limestone

  16. Laccolith • Close relative of the sill; concordant pluton • Slight dome or mushroomshape- middle thicker than sides • Often leaves a bulge at the surface • Can form smaller dome mountains

  17. Laccolith Before & After erosion

  18. Laccolith Sills

  19. Pluton (magma chamber) • Igneous body that has cooled and crystallized beneath the surface • Plutons typically have irregular shapes • Can cause doming at the surface

  20. Stock • Small, discordant pluton • Outcrop area of less than 100 km2

  21. Batholith • Large discordant pluton • Outcrop area is greater than 100 km2 • Most are granitic or felsic in composition

  22. Volcanism Underground(Subterranean Volcanism

  23. Structures you should know

  24. Structures you should know

  25. Another graphic of intrusions

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