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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
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
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.
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