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Landforms created by Lava & Ash - Coggle Diagram
Landforms created by Lava & Ash
Shield Volcanoes
At some places on Earth’s surface, thin layers of lava pour out of a vent and harden on top of previous layers.
An individual flow rarely exceeds 25 feet in thickness. Such lava flows gradually build a wide, gently sloping mountain called a shield volcano.
Shield volcanoes rising from a hot spot on the ocean floor created the Hawaiian Islands.
Cinder Cone
If a volcano’s lava has high viscosity, it may produce ash, cinders, and bombs.
These materials build up around the vent in a steep, cone–shaped hill or small mountain called a cinder cone.
Composite Volcano
Sometimes, lava flows alternate with explosive eruptions of ash, cinder, and bombs. The result is a composite volcano.
Composite volcanoes are tall, steep, cone-shaped mountains in which layers of lava alternate with layers of ash. Many composite volcanoes rise 10,000 feet or more from their base.
Lava Plateaus
Instead of forming mountains, some eruptions of lava form high, level areas called lava plateaus
First, lava flows out of several long cracks in an area. The thin, runny lava travels far before cooling and solidifying.
Again and again, floods of lava flow on top of earlier floods. After millions of years, these layers of lava can form high plateaus.
Caldera
The huge hole left by the collapse of a volcanic mountain is called a caldera.
The hole is filled with the pieces of the volcano that have fallen inward, as well as some lava and ash.
A caldera forms when enormous eruptions empty the main vent and the magma chamber beneath a volcano. The mountain becomes a hollow shell.
With nothing to support it, the top of the mountain collapses inward. Sometimes the caldera left behind fills with water from rain and snow.
Landforms Created by Magma
Dikes & Sills
Magma that forces itself across rock layers hardens like a dike.
Sometimes a dike can be seen slanting through bedrock along a highway cut. When magma squeezes between horizontal layers of rock, it forms a sill.
Volcanic Neck
A volcanic neck looks like a giant tooth stuck in the ground. A volcanic neck forms when magma hardens in a volcano's pipe.
The softer rock around the pipe wears away, exposing the hard rock of the volcano neck.
Batholith
Large rock masses called batholiths form the core of many mountain ranges.
A batholith is a mass of rock formed when a large body of magma cools inside the crust. When the softer rock around the batholith wears away it exposes it.
Dome Mountains
Other, small bodies of hardened magma can create dome mountains.
A dome mountain forms when uplift pushes a batholith or smaller body of hardened magma to the surface. The hardened magma forces the layers of rock to bend upward into a dome shape.
Eventually, the rock above the dome mountain wears away, leaving it exposed.
Fertile Volcanic Soil
People often settle close to a volcano to take advantage of the fertile volcanic soil.
The lava, ash, and cinders that erupt from a volcano are initially barren. Over time, however, the hard surface of the lava breaks down to form a very rich, fertile soil.
Some volcanic soils are among the richest soils in the world.