Geography Series - 7

Hey Guys, What’s up? Let’s study about Volcanoes and its landform today. 

Ø  Volcanoes – a place where gases, ashes and/or molten rock material-lava-escape to the ground.

(This picture must have reminded most of you about your childhood science project where you or your friends have actually made volcano, yes these are the ones we are discussing today. See UPSC is all about General Knowledge and basic Common Sense)

Ø  Types of Volcanoes :-

o   Shield Volcanoes – 2^nd largest after basalt flows Eg Hawaiian volcano, made of basalt – very fluid lava, not steep, explosive only if water enters.

o   Composite volcanoes – like mountains, more viscous lava; along with lava large quantities of pyroclastic materials & ashes find their way to the ground.

o   Caldera – most explosive, collapsed on themselves, collapsed depressions called caldera.

o   Flood Basalt Provinces – highly fluid lava flows for long distances. Eg. Deccan Trap, Maharashtra.

o   Mid-Ocean Ridge Volcanoes- volcanoes in oceanic areas. Length more than 70,000 kms stretching through all oceans.

Ø  Volcanic Landforms

§  Lava released during volcanic eruptions on cooling, forms igneous rocks.

§  Cooling may take place on surface or inside surface.

§  Depending on location of cooling, igneous rocks –

·         Plutonic (cooling beneath surface)

·         Volcanic (cooling at the surface)

Ø  Intrusive Landforms – lava cooling beneath surface.

o   Batholiths – large dome shaped

o   Lacoliths – large dome shaped with a level base & connected by a pipe-like conduit from below. Eg. Karnataka Plateau spotted with domal hills of granite rocks.

o   Lapolith- Saucer shaped, concave to sky body.

o   Phacoliths- wavy material

o   Sill or sheet – horizontal bodies; thinner ones are sheets & thicker ones are sills.

o   Dykes – perpendicular to ground. Eg. West Maharashtra areas.

This was about the Volcanoes and its landforms. In the next article, we will learn about Ocean & Continent distribution.

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