Textbook Connection:
Read Chapter 7
7.1 Volcanoes and Plate Tectonics
7.2 Volcanic Eruptions
Types of Volcanoes:
- Shield volcanoes
- Composite (Strato-) volcanoes
- Cinder cone volcanoes
Types of Lava:
Mafic:
- dark colored (when hardened), rich in Mg (magnesium) and Fe (iron). Forms oceanic crust.
- Mafic lava has a low viscosity and flows easily.
- Seen in slow erupting Shield Volcanoes and hardening into Basalt (extrusive) or Gabbro (instrusive).
- Dominant at Mid-Ocean ridges, Oceanic Hot Spots (Shield Volcanoes of Hawaii), Island Arcs and can be found at Rift Valleys, Continental Hot Spots (Yellowstone).
Felsic:
- lighter colored (when hardened), rich in Si (silica). Forms continental crust.
- Felsic lava has a high viscosity and DOES NOT FLOW EASILY.
- Seen in continental Composite or Stratovolcanoes and result in EXPLOSIVE eruptions. Ex. Cascade Mts. and Mt. St. Helens. Can harden into granite (intrustive) and less likely rhyolite (extrusive).
- Dominant at Oceanic: Continental Convergent plate boundaries/subduction zones and can be found at Continental Hot Spots (Yellowstone).
Volcano Class Resources:
Volcanoes and Other Igneous Activity.ppt
Volcanoes Interactive Lesson
Take an interactive dive to an active submarine volcano
Case of the Missing Rumbleometer
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