earth science 10.1

Chapter 10 section 1volcanoes and other igneous

activity

viscosity• A measure of a

fluid’s resistance to flow.

Pyroclastic materials• Wind will carry

small particles a long way.

• The fragments ejected during eruption range in size from very fine dust and ash to pieces that weigh several tons.

volcano • Anatomy of a volcano

–Activity often begins when a fissure or crack develops in the crust.

–A mountain formed of lava and/or pryoclastic material.

Shield volcanoes • Are produced by the

accumulation of fluid basaltic lava and have quiet eruptions

• Shape of broad slightly domed

• Most have grown from the deep of the ocean including the Hawaiian Islands and Iceland.

Cinder cones• Ejects lava which

hardens in the air and falls back down to form the volcano.

• Produce gas rich basaltic magma

• Short life span: Lasts only a couple of weeks to a couple of years and then it never erupts again.

Composite cones• A combination of

Shield and Cinder cone volcanoes

• Pyroclastic flows can move down the volcano at speeds up to 100 mph.

• Lahars are mudflows caused by melted mountain ice and snow mixed with lava and mud.

Calderas• A large depression

in a volcano caused by the collapse of the top of a volcano after eruption.

• Many lakes form in these depressions.

Volcanic necks and pipes

Lava plateaus

• Greatest volume of lava is excreted from fissures

• Columbia plateau was formed this way

• Numerous fissures erupted to form this large landform.

Key Concept

• What determines the type of volcanic eruption?–The primary factors that determine

whether a volcano erupts violently or quietly include magma composition, magma temperature, and the amount of dissolved gases in the magma.

Key Concept

• What other landforms are associated with volcanic eruptions?–Neck, pipes, and calderas.