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Types of Volcanoes
• Volcano - mountain formed of lava and/or pyroclastic material
• Conduit (pipe) - carries gas-rich magma to surface
Basic Anatomy of a Volcano
• Crater - depression at summit of volcano
Ship Rock, New Mexico, is a
volcanic neck. Ship Rock consists
of igneous rock that crystallized in
the pipe of a volcano that then was
eroded away.
Types of Volcanoes1) Shield Volcanoes - broad, gently sloping (built from fluid basaltic lavas)
Ex. Mauna Loa in Hawaii
-- Eruptions usually mild & can occur several times
-- Magma has a LOW viscosity
Shield Volcanoes
2) Composite Cones/Stratovolcano – built from both lava flows &
pyroclastic material. Large steep slopes
- Most near Pacific Ocean (Ring of Fire).
- Magma has HIGH viscosity
- Most violent Eruptions!
Pyroclastic Material: Hot
material (from ash size to
bombs size fragments) with
minimal lava that is thrown
from vent and results in the
formation of steep sides
Anatomy of a Composite Volcano
The Eruption of
Mt. St. Helens
Mount St. Helens Before and
After the May 18, 1980, Eruption
3) Cinder Cones - small size, steep slope, (built from pyroclastic material)
-- Tend to be active for a short time, then they go dormant
-- Explosive due to high gas content in Magma
Cinder Cones
Profiles of Volcanic Landforms
Other Volcanic Landforms Calderas - large depressions in volcanoes.
• Formed by collapse of the summit into the emptied magma chamber
• Nearly circular
• Size exceeds 1 km in diameter
Read 10.1 for more information to improve your knowledge of
the content in this lecture and to improve activity/test scores
Composite Cone: Lava Layers,
Crater, Magma Chamber,
Conduit, and Pyroclastic Flow
Layers (pg. 283)
Shield Volcano: Lava Layers,
Crater (summit), Magma
Chamber, and Conduit (pg. 284)
Cinder Cone: Crater, Conduit,
and Pyroclastic Flow Layers
(pg. 285)
DRAW AND LABEL THE THREE FOLLOWING VOLCANO TYPES: