The document discusses factors that affect the violence of volcanic eruptions including the composition, temperature, and dissolved gases of magma. More viscous magma produces more violent eruptions as gases cannot escape as easily. There are three main types of volcanoes - shield volcanoes formed from fluid basaltic lava, cinder cones formed from pyroclastic material from a single vent, and composite cones which are the most violent type formed from both lava and pyroclastic material. The document also briefly mentions plutons, which are intrusive igneous rocks that form from cooling magma underground.

1. Prentice Hall
EARTH SCIENCE
Tarbuck Lutgens

2. Chapter
10
Volcanoes and Other
Igneous Activity

3. Factors Affecting Eruptions
10.1 The Nature of Volcanic Eruptions
 Factors that determine the violence of an
eruption
• Composition of the magma
• Temperature of the magma
• Dissolved gases in the magma
 Viscosity
• Viscosity is the measure of a material's
resistance to flow.

4. Factors Affecting Eruptions
10.1 The Nature of Volcanic Eruptions
 Dissolved gases
• Violence of an eruption is related to how easily
gases escape from magma
- Gases escape easily from fluid magma.
- Viscous [THICKER] magma produces a
more violent eruptions.

5. Magma Composition

6. Pahoehoe (Ropy) Lava Flow

7. Volcanic Material
10.1 The Nature of Volcanic Eruptions
 Pyroclastic Materials
• Pyroclastic materials is the name given to
particles produced in volcanic eruptions.

8. Types of Volcanoes
10.1 The Nature of Volcanic Eruptions
 The three main volcanic types are shield
volcanoes, cinder cones, and composite
cones.

9. Anatomy of a “Typical” Volcano

10. Types of Volcanoes
10.1 The Nature of Volcanic Eruptions
 Shield Volcanoes
• Shield volcanoes are broad, gently sloping
volcanoes built from fluid basaltic lavas.
• Cinder cones are small volcanoes built primarily
of pyroclastic material ejected from a single vent.
 Cinder Cones

11. Shield Volcanoes

12. Cinder Cones

13. Types of Volcanoes
10.1 The Nature of Volcanic Eruptions
 Composite Cones
• Composite Volcanoes are volcanoes composed
of both lava flows and pyroclastic material.
- Most violent type of activity

14. Composite Cones

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

16. Profiles of Volcanic Landforms

17. Plutons
Plutons are intrusive igneous
structures that result from the cooling
and hardening of magma beneath the
surface of Earth.
10.2 Intrusive Igneous Activity

18. Types of Igneous Plutons