Landforms Made from Volcanoes

Lava Plateaus

Sometimes, lava does not form mountains

Lava flows out of crust and collects in one area, forming a high plateau

Calderas

Enormous eruptions can empty the magma chamber under the volcano

With nothing left for support, the mountain collapses

Caldera

The hole left over is a caldera

Soils from Lava

Initially, lava hardens and destroys plants.

Eventually, the lava breaks down and produces good soil that supports plants.

Landforms from Magma

Sometimes, magma does not leave the vent and gets trapped under ground.

Eventually, all the other rock around the lava wears away and leaves the hardened magma behind.

Landforms from Magma

Volcanic necks form from magma that hardens in the volcano pipe.

Landforms from Magma

A batholith is a large rock that forms when a large body of magma cools in the crust.

Landforms from Magma Dome mountains are formed when

magma is blocked by rocks.

The magma pushes rock layers up, making small mountains.

Volcanic Activity

How Does it Erupt?

Volcanoes are like cans of soda pop

Lots of gas is trapped inside the magma under pressure

During an eruption, the gases rush out and carry magma with them

Inside a Volcano

Volcanoes have a pocket of magma beneath is and cracks where magma can force through

Magma sits below the volcano in a magma chamber

Inside a Volcano

Magma travels to the surface through a pipe

Magma and gases leave through a volcano vent

Inside a Volcano

A lava flow is the area covered by the moving lava

A crater forms at the top of the volcano around the vent

Characteristics of Magma How forceful an explosion is

depends on: How much gas is in the magma How thick or thin the magma is? Temperature Silica content

Characteristics of Magma

Magma that is thick flows slowly.

The hotter the magma, the faster it flows.

Silica

Earth’s crust and mantle are mostly made of silica

The more silica in the magma, the thicker it is

Silica

Magma with a lot of silica makes light-colored lava that is very thick

When high silica lava cools, it makes rocks like rhyolite, pumice and obsidian

Silica

Magma that does not have much silica moves quickly and is thin.

Low silica magma is dark colored and makes rocks like basalt