Various types of landforms are produced by the volcanoes. They can be grouped into
1. Extrusive landforms
2. Intrusive landforms
1. Extrusive landforms: The landforms which have been formed due to the accumulation and solidification of lava and other materials given out by volcanoes are known as extrusive landforms. The important extrusive land forms are:
a. Volcanic cones: volcanic cones are the most typical form of extrusive features or landforms.
The lava and other ejected materials that reach the surface of the earth are accumulated around the crater, and cones are formed. The formation of cones depends jupon the nature of explosion and the materials emitted out of it. There fore, cones are various types. They are:
- Cinder cones: A volcanic cone formed by volcanic cinder accumulated around the crates is called cinder cone.
- Ash cone: A cone shaped hill formed by of volcanic ash that is built up around a volcanic ent is called ash cone.
- Composite cone: A volcanic cone composed of alternative layers of ash, cinder and lava is called composite cone.
- Parasite cone: Some times, many smaller cones are developed in the neighborhood of the main cone. They are called parasite cone.
b. Crater: A crater is pit at the top of volcanic vent, during volcanic eruption, materials form the top of the cone are blown off and a bowl shaped depression is formed. It is known as crater. Caldera: Sometime a violent explosion blow away the original cone and forms a large basin-shaped depression called caldera
Volcanic spine: The acid lava, which is vicious, solidifies quickly and blocks the vent. This stands up as a steep-sided cone called spine or plug.
Lava dome: The shape of lava dome is determined by the nature of lava. The highly fluid basic lava builds up shield dome with gently rising slopes, and flattened top. The basic lava, which is highly viscous, builds up dome with a great height and steep slope
Lava plateau: An extensive elevated land made up of depositional lava called lava plateau.
2. Intrusive land forms: Intrusive landforms occur when lava solidifies with the earth’s. crust and gives rise to various shapes or forms. Intrusive landforms are formed along the bedding planes of sedimentary rocks. There are various forms of intrusive landforms. They are:
Dyke: The Magma from the interior of the earth finds its way towards the surface through a passage. When it is able to reach the surface, it cools and solidifies, and a vertical or highly inclined feature is formed, and such a features is called dyke.
Sill: A sheet of magma which lies along the bedding plan is called sill. Laccolith: Laccolith is a large mound of igneous rock formed along a bedding plane in the sedimentary rock layers.
Batholith: Batholith is a very large dome – shaped intrusion of igneous rock. It is exposed to the surface only after considerable erosion.
Hot springs or thermal spring’s are more common. The water sinks deep inside where the rocks are heated. The heated water rises to the surface without any explosion. Such springs contain dissolved minerals which are of medicinal value. They can be also used to generate electricity. Iceland has thousands of hot springs. A Geyser is a hot spring form which a column of hot water and stream are alternatively ejected to a great height.
