Geology Viva Voce

Useful for Engineering students for Engineering Geology Lab, Degeree and M.Sc in Geology, Applied Geology and GIS.

Geology viva questions and answers/ oral questions and answers prepared by: Tejashwini N.C, M.Sc; Asst. Prof. in Geology

1. The shape of the Earth is:
Answer: Geoid

2. Age of the Earth is
Answer: 4.6 billion years

3. Sial and Sima are separated by
Answer: Conrad discontinuity

4. Morhorovicic discontinuity is found between
Answer: Crust and Mantle

5. Mantle and Core are separated by
Answer: Gutenberg discontinuity

6. The term ‘NiFe’ refers to
Answer: Core of the Earth

7. The plastic layer of the mantle is called
Answer: Asthenosphere

8. The composition of Sial is
Answer: Granitic to grano dioritic

9. The composition of Sima is
Answer: Basaltic

10. The polar and equatorial diameter of the Earth is
Answer: 12,713 km and 12,756 km


11. The process of disintegration and decomposition is called
Answer: Weathering

12. The process of Erosion includes
Answer: Disintegration

13. Frost action takes place due to
Answer: Freezing of water

14. Which minerals are highly susceptible to chemical weathering
Answer: Ferromagnesian Minerals

15. Which are characteristic functions of the geomorphic agents
Answer: Erosion, Transportation and Depositional works

16. William Morris Devis has recognised the stages involves in a cycle of river erosion are
Answer: Initial stage, Youth stage, Mature stage and Old stage

17. In which stage of erosional cycle maximum changes occur
Answer: Mature stage

18. Waterfalls and Gorges are characteristic features of the river in
Answer: Initial stage

19. Pot holes are formed generally by
Answer: Abrassion or Corrosion

20. Chemical erosion by river water is known as
Answer: Corrosion

21. The transportation by Creeping and Rolling is known as
Answer: Traction

22. The plain land produced by the river action is
Answer: Peneplain

23. Deltas are formed in
Answer: Old Stage of the River

24. The transportation through lifts and falls of materials is known as
Answer: Saltation

25. Which type of drainage pattern develops in folded or tilted beds
Answer: Trellis pattern

26. Canyon is
Answer: A deep valley with steep near vertical sides

27. Pass is
Answer: An opening between the Mountains

28. Aeolian topography is created by the geological action of
Answer: Wind

29. Yardang topography associated with
Answer: Wind action

30. Which instrument is used to measure the wind velocity
Answer: Anemometer

31. Loess is
Answer: Homogeneous and unstratified deposit of silt

32. A Crescent shaped dune with two tapering arms is known as
Answer: Barchan

33. Wind ripples are generally formed by
Answer: Saltation movement of sand grains

34. A normal sand-dune is characterised by
Answer: Gentle windward and Steeper leeward sides

35. Blow-outs are
Answer: Broad shallow depression in desserts

36. When one wing of a Barchan is missing, then it is known as
Answer: Seif

37. The space between the dunes is known as
Answer: Gassis

38. Chinook is a local hot wind which flows mostly in
Answer: USA and Canada

39. Which abrasion is more effective in rounding the sand grains
Answer: Wind abrasion

40. “Lag-Gravel” is
Answer: The coarse sediments left behind where wind has removes the finer grain sizes

41. Glaciers are formed by
Answer: Compaction and Re-crystallisation of snow

42. Ne’ve’ or Flrn are
Answer: Granular ice mass

43. The polar glaciers are
Answer: Below the freezing point throughout the year

44. The Karst topography developed due to the action of
Answer: Groundwater

45. Which process is mainly responsible for development of the Karst topography
Answer: Chemical Process

46. The columns of limestone that hang from the ceiling downwards are known as
Answer: Stalactites

47. Stalagmites are
Answer: Rising up vertically from the floor of the cavern

48. Blind valleys are found in
Answer: Karst topography

49. Drip-stones are
Answer: Columns formed by joining of Stalactite and Stalagmite

50. ‘Terra rossa’ is
Answer: Residual red soil occurring on limestone in Karst region

51. The difference between lake and basin is
Answer: Lakes commonly occur above the mean-sea level while basins have their bottoms below the water table.

52. Dhands are
Answer: Small lakes of Aeolian origin

53. A narrow strip of water joining the two water bodies is called
Answer: Strait

54. The ocean which is between Africa and Australia
Answer: Indian Ocean

Crystallography & Mineralogy

55. The faces, edges and solid angles have a definite relationship with each other. This relationship is expressed by
Answer: Euler’s formula

56. Euler’s formula is
Answer: F+A = E+2

57. Centre of symmetry is
Answer: Repetition is with respect to a point

58. Axis of Symmetry
Answer: Repetition is with respect to a line

59. Plane of Symmetry
Answer: Repetition is with respect to a plane

60. Which instrument is used to measure the interfacial-angle of crystals
Answer: Goniometer

61. Which crystal system is having maximum of classes
Answer: Hexagonal system

62. In which crystal system majority of minerals crystallises
Answer: Monoclinic system

63. The Isometric system is characterised by
Answer: 4 axes of 3 fold symmetry

64. What is the normal interfacial angle in dodecahedron form of cubic system
Answer: 600

65. Gyroidal class belongs to
Answer: Isometric system

66. The cleavages in twinned crystals are
Answer: In different directions

67. Butterfly twinning is seen in
Answer: Gypsum

68. Pericline twin is found in
Answer: Plagioclase

69. The degree of transparency of a mineral is known as
Answer: Diaphaneity

70. Give an example of a mineral in which cleavage is absent
Answer: Quartz, Corundum

71. Hardness of human nail varies between
Answer: 1.5 to 2.5

72. Hardness is which kind of property
Answer: Anisotropic (A mineral may show different values in different directions.)

73. The tendency of a crystallized mineral to break along certain directions yielding more or less smooth, plane surface is
Answer: Cleavage

74. The behaviour of a mineral towards the forces that tend to destroy it is called
Answer: Tenacity

75. A Mineral is
Answer: Naturally occurring inorganic substance with definite chemical composition

76. The external appearance of a Mineral is known as
Answer: Habit/ Form

77. The powered form of a mineral is
Answer: Streak

78. Shining property of a Mineral is
Answer: Lustre

79. Form in which neither a crystal face nor a cleavage is seen in
Answer: Amorphous

80. Quartz shows which lustre
Answer: Vitreous

81. Which mineral shows silky lustre
Answer: Asbestos, Gypsum

82. Mica is
Answer: Flexible and elastic

83. Kyanite shows which form
Answer: Bladed

84. Structure or form which depicts leaf like sheets is
Answer: Lamellar

85. Muscovite mica shows which structure
Answer: Foliated

86. Which form resembles human kidney
Answer: Reniform

87. chromite shows which type of structure
Answer: Granular

88. Colour changing phenomenon which involves oxidation is
Answer: Tarnish (A phenomenon of change of original colours of minerals to some secondary colours at its surface due to oxidation at the surface)

89. Diamond shows which type of lustre
Answer: Adamantine

90. Streak is an important diagnostic property of
Answer: Coloured minerals

91. Generally which minerals give streak
Answer: Coloured and opaque

92. Hardness of a mineral depends upon
Answer: Chemical composition and atomic constitution

93. The scale of hardness is
Answer: Mohs (It was in 1822 that Austrian mineralogist F. Mohs proposed a relative, broadly quantitative “scale of hardness” of minerals assigning values between 1 to 10)

94. Which mineral group is abundantly found in the Earth’s crust
Answer: Feldspar group (Second abundant is Silicate or Quartz group)

95. Feldspar is found majority in which kind of rock
Answer: Igneous rocks

96. Acicular habit shown in
Answer: Natrolite

97. Violet colour of Amethyst is due to
Answer: MnO2

98. The mineral which can be cut and powdered are known as
Answer: Sectile

99. Opaque minerals indicate their origin from a
Answer: Rapidly cooled silicate melt

100. Orpiment and Realgar are Sulphides of
Answer: Arsenic

Optical Mineralogy

101. In natural light, the elctro-magnetic vibrations are:
Answer: Always perpendicular to the direction of light-wave prorogation

102. Refractive index depends upon
Answer: Nature of the substance and Kind of light used

103. The refractive index of Canada balsam is
Answer: 1.54

104. Plane polarised light can be produced by
Answer: Nicol prism, Reflections, Absorption

105. Backe-line method is used to determine the
Answer: Refractive index

106. Which property determines the colour
Answer: Wavelength

107. The wavelength varies from slightly more than …. at the red end to about …. at the violet end
Answer: 7000 Å and 4000 Å respecively

108. The isotropic substance has
Answer: A single refractive index

109. Double refraction phenomenon shown by
Answer: Anisotropic substance

110. The angle between the reflected and refracted ray is 900, stated by
Answer: Brewster’s law

111. Which crystal systems are optically uniaxial
Answer: Hexagonal and Tetragonal

112. Which crystal systems have two optic axis
Answer: Orthorhombic, Monoclinic and Triclinic

113. Uniaxial crystal are positive if
Answer: Ordinary ray has the greater velocity than the Extraordinary ray

114. The difference between the maximum and minimum indices of a particular mineral is known as
Answer: Birefringence

115. What is the birefringence of Quartz mineral
Answer: 0.009

116. Birefringence is used to determine
Answer: Thickness of section

117. Bereck compensator is an optical device which is made up of
Answer: Calcite

118. The order of interference colour is determined by
Answer: Quartz plate

119. A Polaroid is a
Answer: Light filter

120. Biaxial minerals show
Answer: Symmetrical extinction

121. Complete extinction occurs only when the section is
Answer: Perpendicular to optic symmetry

122. Which is also known as Glimmer plate
Answer: Gypsum plate

123. Amorphous substance are
Answer: Anisotropic

124. Orthoclase is distinguished from Quartz in thin section by
Answer: Low refractive index, Type of twinning and Negative sign

125. The Michael-Levy method is used to determine the extinction angle of
Answer: Plagioclase

126. Which plate is generally used to determine the optical sign of plagioclase
Answer: Selenite plate

127. The Orthopyroxenes show interference colour of
Answer: 1st order

128. Which type of extinction is often shown by Quartz mineral
Answer: Wavy

129. Calcite is characterised by
Answer: Rhombohedral cleavage, low interference colour and optically negative character

130. Calcite and Magnesite can be distinguished from one another in thin section
Answer: Magnesite is never twinned