Q. 1. What is a rock ?
Ans. Solid materials of lithosphere.
Q. 2. Name the three main types of rocks.
Ans. (i) Igneous rocks (ii) Sedimentary rocks (iii) Metamorphic rocks.
Q. 3. What does the word Igneous stand for ?
Ans. Derived from the Latin word ‘Igins’, it means fire.
Q. 4. Why does lava cool rapidly on the surface of earth ?
Ans. Due to contact with atmosphere.
Q. 5. State one example of extrusive Igneous rocks.
Q. 6. On the basis of location, name two types of Igneous rocks.
Ans. Extrusive and Intrusive rocks.
Q. 7. Name the three types of Igneous rocks on the basis of origin.
Ans. Volcanic rocks, Hypabyssal rocks and Plutonic rocks.
Q. 8. From which word, the term Plutonic is derived ?
Ans. From Pluto (the God of underworld)
Q. 9. State one example of Plutonic rocks.
Q. 10. What does the term ‘Batholith’ mean ?
Ans. Batholith is a dome-shaped granitic mass of intrusive Igneous rocks.
Q. 11. What are laccoliths ?
Ans. Laccoliths are mounds of magma forced from below.
Q. 12. Name an extensive area in Western India covered with Basalt.
Ans. Deccan trap.
Q. 13. Name three types of sedimentary rocks according to mode of formation.
Ans. (i) Mechanically formed
(ii) Chemically formed
(iii) Organically formed.
Q. 14. Name three examples of mechanically formed sedimentary rocks.
Ans. Sandstone, Grit, Clay.
Q. 15. What is Grit ?
Ans. Coarser sandstone is known as Grit.
Q. 16. What is Conglomerate ?
Ans. When large rounded pebbles are cemented together conglomerate is formed.
Q. 17. Name one example of Carbonaceous rocks.
Q. 18. Name the different types of coal.
Ans. Peat, Lignite, Bituminous and Anthracite.
Q. 19. Name two examples of calcareous rocks.
Ans. Chalk and limestone.
Q. 20. Name two fossil fuels found in sedimentary rocks.
Ans. Coal and petroleum.
Q. 21. Name two examples of chemically formed rocks.
Ans. Gypsum and Rock salt.
Q. 22. To which rock are granite and basalt changed ?
Ans. Granite to gneiss. Basalt to schist.
Q. 23. To which rocks are shale and coal changed ?
Ans. Shale to slate; coal to graphite.
Q. 24. What does ‘lithosphere’ mean ?
Ans. A sphere of rocks.
Q. 25. Who is a Petrologist ?
Ans. A scientist who studies rocks.
Q. 26. Why is the knowledge of rocks necessary ?
Ans. As there is a close relation between rocks and land-forms and between rocks and soils, it is necessary for a geographer to have basic knowledge of rocks.
Q. 27. Classify rocks on the basis of their mode of formulation.
Ans. Rocks are grouped under three families on the basis of their mode of formation. (i) Igneous rocks solidified from Magma and Lava. (ii) Sedimentary rocks—The result of deposition of fragments of rocks of external agents. (iii) Metamorphic rocks—formed in recrystallisation.
Q. 28. What do you mean by Petrology ?
Ans. Petrology is the science of rocks. A petrologist studies rocks in all their aspects viz. mineral composition, texture, structure, origin occurrence, alteration and relationship with other rocks.
Q. 29. What do you mean by lithifiction ?
Ans. Rocks are broken into various sizes of fragments. These are deposited. These deposits through compaction or cementation turn into rocks.
Q. 20. What is meant by PVT ?
Ans. It is a brief form of metamorphism.
P = pressure V = volume T = temperature.
These three are included in this process.
Q. 21. What is meant by metamorphism ?
Ans. Metamorphism means change of form. It is a process by which already consolidated rocks undergo recrystallisation and reorganisation of materials within original rocks.
Q. 22. What is meant by Rock Cycle ?
Ans. Rock cycle is a continuous process through which old rocks are transformed into new ones.
Q. 23. Define Rocks. Name the main types of rocks.
Ans. Any natural, solid inorganic or organic material out of which the crust is formed is called a rock. It may be hard as granite or soft as clay. Clay, chalk, coal, gravel, etc. are examples of rocks.
Lithosphere is made up of rocks. On the basis of their mode of formation, rocks are divided into three types : (i) Igneous rocks.
(ii) Sedimentary rocks.
(iii) Metamorphic rocks.
Q. 24. How are Sedimentary rocks formed ?
Ans. Sedimentary rocks have been formed by the deposition of sediments brought by wind, ice and river. The sediments are deposited in depressions, lakes and sea. Loose sediments are deposited on horizontal layers. These layers are parallel to one another. These sediments are bonded together by the pressure of upper layers and some cementing material such as silica, calcite, etc.
Q. 25. Why are the Igneous rocks called Primary Rocks ?
Ans. It is believed that the earth was in a molten state in the beginning. Igneous rocks were the first rocks to be formed due to cooling and solidification of molten matter. Hence, these are called Primary Rocks.