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.

Hope you guys are finding these series useful. Our endeavor is to make your preparation more simple and fun. If you have suggestions to make it better, please let us know.

Also, keep sharing your reviews.

Ciao !

Geography Series - 6

Hey Guys, today we will study about Types of Rocks.

Ø  98% earth’s crust composed of 8 elements – Oxygen, Silicon, Aluminium, iron, calcium, sodium, potassium & Magnesium.

Ø  Mineral – Naturally occurring organic & inorganic substance. Normally composed of 2 or more elements but sometimes single element minerals like Sulphur, Copper, Gold, etc are also present.

Ø  Basic source of mineral – magma in interior of earth.

Ø  Hardness of mineral is relative resistance to scratch. 10 minerals to measure degree of hardness are:

1.      Talc (Softest)                     6. Feldspar

2.       Gypsum                              7. Quartz

3.       Calcite                                8. Topaz

4.      Fluorite                               9. Corundum

5.      Apatite                                10. Diamond (Hardest)

o   Fingernail – 2.5

Ø  Major minerals are:

o   Feldspar – Silicon + Oxygen with Calcium, Aluminum, Sodium, Potassium may present in some variety. Half of earth’s crust is Feldspar. Used in ceramics & glass making.

o   Quartz – consists of silica. Used in radio & radar. Granite – quartz + Feldspar.

o   Pyroxene – Calcium + Aluminium + Magnesium + Iron + Silica; forms 10% earth’s crust; found in meteorites.

o   Amphibole – Aluminium + Calcium + Silica + Iron + Magnesium; 7% earth’s crust; Used in asbestos.

o   Mica – Potassium, Aluminium, Magnesium, Iron, Silica,etc. 4 % earth’s crust; used in electrical instruments.

o   Olivine – Magnesium + Iron + Silica; Used in jewellery.

Ø  Minerals are of two types:

o   Metallic-containing metal like gold, silver, platinum, iron, etc.

o   Non metallic- containing non-metals like sulphur, phosphates, and nitrates. Cement- mixture of non-metals.

o   (Metals are hard, opaque, shiny and generally good conductor of heat & electricity).

Ø  Rocks – aggregate of one or more minerals.

Ø  Types of Rocks

 

Ø  Rock Cycle

Ø  This was all about Rocks & mineral you need to remember. Please remember examples of different types of rocks and a bit of major mineral. If you are lucky, they may come directly in the exam. Study hard, get lucky.

Ø  In the next article, we will start with Landforms.

Ø  Ciao !