1. A coal seam is exposed on a horizontal ground. If it is 30° towards West. Its width of outcrop on a level ground is 360 m. What is its true thickness?
a) 120 m
b) 150 m
c) 160 m
d) 180 m
Explanation: The equation to calculate True thickness is given by
True thickness = Width of outcrop * Sin 30°
By substitution and calculation, we get 180 m.
True thickness = 360 * sin (30°) = 180 m
2. At a dam site, a bed of sandstone is exposed on horizontal ground. If it is 25° towards East. Its width of outcrop on a level ground is 240 m, what is its vertical thickness?
a) 101.9 m
b) 99.9 m
c) 111.9 m
d) 121.9 m
Explanation: Vertical thickness = Width of outcrop * tan (angle of inclination)
Vertical thickness = 240 * tan (25°) = 111.91 m
3. The study of outcrop dimensions doesn’t involve which of the following aspect?
a) Width
b) Thickness and depth
c) Dip and strike
d) Rock composition and type
Explanation: The study of rock composition and type of rock is not done under the outcrop dimensions whereas the rest are thoroughly studied under the topic.
4. Foliation is a primary structure of which type of rock?
a) Igneous rock
b) Sedimentary rock
c) Metamorphic rock
d) Not associated with any rock
Explanation: Stratification and lamination are the most common primary structures of sedimentary rocks; crystalline structure is typical of igneous rocks and foliation is a typical primary structure of metamorphic rocks.
5. The dip of a layer measured in the direction that is at the right angle to strike is _____________
a) True dip
b) Apparent dip
c) Straight dip
d) Normal dip
Explanation: When the dip of a layer is measured in a direction that is essentially at right angles to the strike of that particular layer, then it is called true dip. When the dip of a layer is measured in any other direction, which is not at right angles to its strike direction, it is called an apparent dip.
6. What are the undulations or bends developed in rocks called?
a) Faults
b) Joints
c) Folds
d) Uncomformity
Explanation: Folds may be defined as undulations or bends or curvatures developed in the rocks of the crust as a result of stresses to which these rocks have been subjected from time to time in the past history of the Earth.
7. Folds develop in which type of rock?
a) Igneous rock
b) Sedimentary rock
c) Metamorphic rock
d) Any type of rock
Explanation: The folds may develop in any type of rock and may be of any shape and flexures.
8. Which type of deformation is folding?
a) Brittle
b) Ductile
c) Tensile
d) Malleable
Explanation: In general, folding is a ductile type of deformation experienced by the rocks compared to the brittle deformation where the rocks actually get broken and displaced when stressed.
9. Folding is ________ process.
a) Very slow
b) Rapid
c) Quick
d) Moderate rate
Explanation: Folding is a very slow geological process and indicates an effort of the rocks in a particular environment to adjust themselves to the changing force fields operating on, within or around them.
10. Which among the following is not a part of fold?
a) Limbs
b) Hinge
c) Axis of fold
d) Height of fold
Explanation: Parts of a fold include, limbs, hinge, axis of a fold, plunge of a fold and crest & trough. Height of fold is not referred as its part.