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Rocks, Weathering and Erosion - Physical Geography
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Through this lesson, Bhanwar has explained various rock types and also the phenomenon of weathering and erosion.

Bhanwar Singh
Ex- National Defence Academy (115 Course) Cleared Civil Services Examination, 2012

Unacademy user
Nice session but it would be much more better if you've dealt with things like: 1) role of REM sleep on long-term memory, 2) Memory Palace Technique. Thanks again for wonderful session :)
Materiel is good. No doubt about the expertise in the subject matter BUT.. But, difficult to follow or catch the explanation. Hard to make out whether reading or explaining a topic due to the same pitch and tone above all the cursor/marker in red is not helping. The marker never follow along the word while reading
Sir the lesson really good but lesson on earthquakes and volcanoes is incomplete
Mr. Sirohi any particular reason for not continuing with Military career ?
thank you sir !!@@!@
  1. CRASH COURSE-WORLD GEOGRAPHY Presented by - Bhanwar Singh Sirohi


  3. ABOUT ME BA. (Hons) in Law from Awadh University I Defence Academy (115 Course) Cleared Civil Services Examination, 2012 Hobbies - Writing Poetry Course Fee Contribute Follow me on Unacademy at:

  4. ELEMENTS Rocks are composed of various minerals and elements More than 1 10 elements are found in the earth crust Out of them only 8 are major rock forming minerals and they constitute about 98% of the earth crust In decreasing percentage of order, these 8 elements are 1. Oxygen 2. Silicon 3. Aluminium 4. Iron 5. Calcium 6. Sodium 7. Potassium 8. Magnesium

  5. MINERALS Number of minerals on the earth crust is more than 2000 Out these 24 minerals are called Rock Forming Minerals Out of these 24 minerals, 6 are found in large amount 1. Feldspar 2. Quartz 3. Pyroxine 4. Amphiboles 5. Mica 6. Olivine

  6. TYPES OF ROCKS (MODE OF ORIGIN) There are three types of Rocks on the basis of mode of origin IGNEOUS ROCKS . SEDIMENTARY ROCKS 2 METAMORPHIC ROCKS 3

  7. IGNEOUS ROCKS Also known as Primary or Basic rocks These are formed due to cooling and solidification of molten magma These rocks are granular and crystalline and no layers are found Igneous rocks can occur in two ways-either on the surface of the earth (Extrusive lgneous Rocks) or within the crust (Intrusive Igneous Rocks) The intrusive igneous rocks are coarse whereas the extrusive igneous rocks are fine-grained On the basis of mineral and chemical composition, these rocks may also be classified into - Felsic, Mafic or Ultramafic rocks

  8. SEDIMENTARY ROCKS Formed on the surface of the Earth due to erosion and deposition of igneous and metamorphic rocks Found over about 95% area of the Earth's crust but they contribute only 5% during the formation of the crust Contain fossils and are layered or stratified rocks They can be classified into three group on the basis of the nature of sediments Mechanical lly formed - sandstone,conglomerates, clay, etc a Organically formed- limestone,coal, peat, etc Chemically formed-chalk, gypsum, salt rock, etc

  9. METAMORPHIC ROCKS a Formed due to temperature and pressure o There is complete change in appearance and constitution of parent rock due to change in mineral composition and texture Hardest and do not contain fossils Metamorphic Rock Slate Quartzite Parent Rock Shale & Clay Sandstone & Conalomerate Granite Phyllite Metamorphic Rock Parent Rock Amphibolites & Schist Basalt Marble Limestone, Chalk & Dolomite Slate Gabbro Gneiss Phyllite Schist Serpentine

  10. ROCK CYCLE Rock Cycle Sedimentary Rock Magma Igneous Rock Metamorphic Rock Pressure a e a nd Temperature