Remember the melting point range of most rock?

Magma that is made up of Basalt with a low (50%) silica content.

What is Viscosity ?

The temperature and composition of the magma determines the viscosity of magma.

This volcano is a mountain with broad gently sloping sides and a nearly circular base.

The Hawaiian Islands - Kilauea is an example of a

These volcanoes are steep sided and generally small

(less than 500 meters high). They are formed when material ejected high into the air falls back to Earth and piles up around the vent.

—An example of this type of volcano is Paricutin in Mexico

These are larger than other volcanoes and their slopes are not as steep. They are formed when layers of volcanic fragments alternate with lava flows.

—EXAMPLES: Mount St. Helens and Mount Rainier of the Cascade Range in North America.

These are rock fragments that are thrown high into the air.

Clouds of hot (700° C) poisonous gas, ash and other tephra that moves down slope at speeds up to 200 km/hr.

The larger belt of convergent boundary volcanoes is called

—The kind of volcanic eruptions that occur at divergent boundaries are Rift zone eruptions.

These are unusually hot regions of Earth’s mantle where high temperature plumes of mantle material (magma) rise towards the surface

—Hot spots form a trail of progressively older volcanoes when the plates above them move laterally

An Example is

—The volcanoes that form over hot spots tell us the rate and direction of motion of the tectonic plates.