1. 10.1 Types of Volcanoes Anatomy of a Volcano
• Volcano - mountain formed of lava and/or pyroclastic material
• Crater - depression at summit of volcano
• Conduit (pipe) - carries gas-rich magma to surface
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.

2. 10.1 The Nature of Volcanic Eruptions
Types of Volcanoes
1) Shield Volcanoes - broad, gently sloping (built from fluid
basaltic lavas)
-- Eruptions usually mild & can occur several times
--Magma has a LOW viscosity
- Ex. Mauna Loa in Hawaii

3. Shield Volcanoes

4. 2) Cinder Cones - small size, steep slope
Pyroclastic Material-- Hot ash & minimal lava thrown from vent forming steep sides
--Tend to be active for short time, then go dormant
-- Explosive due to high gas content in Magma
Ex: Paricutin in Mexico

5. Cinder Cones

6. 3) Composite Cones - composed of both lava flows & pyroclastic material. Large steep slopes
-most violent Eruptions!
- Magma has HIGH viscosity
- Most near Pacific Ocean (Ring of Fire).

7. Anatomy of a Composite Volcano

8. The Eruption of Mt. St. Helens
                                               

9. Mount St. Helens Before and After the May 18, 1980, Eruption

10. Profiles of Volcanic Landforms

11. Other Volcanic Landforms
Calderas - large depressions in volcanoes.
• Nearly circular
• Formed by collapse
• Size exceeds 1 km in diameter

12. Which type of volcano is the smallest and most abundant and tends to be active for short periods of time?
Shield
Composite
Cinder cone
Cinder cone volcanoes:
Smallest and most abundant
Large amount of trapped gas creating violent eruptions
Vast amounts of hot ash & lava are thrown from the vent
These particles fall to the ground around the vent forming the cone
Tend to be active for a short time and then go dormant