Science Lesson 1

refers to an opening or vent in a planet’s crust from which molten rock, ash (pulverized rock and pumice) and gases from below

what are the three classification of volcanoes

if it has erupted within the last 10,000 years . This definition would include approximately 1,500 active volcanoes worldwide.

• active

• inactive/dominant

• extinct

if it has not erupted in historical times.

• active

• inactive/dominant

• extinct

The Composition of Magma Determines whether it is explosive or not: High water content

• more likely to be

• unlikely

The Composition of Magma Determines whether it is explosive or not: High silica content

• more likely to be

• unlikely

Answer explanation

Silica has a thick, stiff consistency, Flows slowly– Tends to Harden in the volcano’s vent

magma that flows onto the Earth’s surface

Rock fragments created by eruptions, magma explodes from volcano and solidifies in the air, existing rock is shattered by powerful eruptions

A tall mountain with a crater on top from which pyroclastic (fire-broken)materials, gases and lava escape

almost flat and broad like a warrior’s shield