Engineering Geology Multiple Choice Questions on “Folds & Folding Basic Terms”.
1. The branch of geology which deals with the morphology, classification, mechanism and causes of development of these rock structures is called as ___________
a) Rock geology
b) Structural geology
c) Basic geology
d) Lithology
Answer: b
Clarification: The basic definition of structural geology is “the branch of geology which deals with the morphology, classification, mechanism and causes of development of these rock structures”. Hence the answer Structural Geology.
2. Stratification can be seen widely in which of the following rocks?
a) Igneous rocks
b) Metamorphic rocks
c) Sedimentary rocks
d) Fossil rocks
Answer: c
Clarification: Most sedimentary rocks are deposited under conditions which favour development of distinct layers piled up one above another, from bottom to top. These layers also called beds or strata.
3. Outcrop is seen on land everywhere on earth.
a) True
b) False
Answer: b
Clarification: Solid rocks are not exposed everywhere on the surface of the earth. These are mostly covered with a thick or thin layer of loose deposit called alluvium or in most common language as soil. Hence rock or the outcrop is not seen everywhere on earth.
4. Most widespread rock on earth is _____________
a) Igneous rock
b) Sedimentary rock
c) Metamorphic rock
d) All are in equal quantities
Answer: b
Clarification: It is said that sedimentary rocks are superficially the most widespread rocks, forming more than 75% of the exposed surface of the earth.
5. Which of the following about lamination is not true?
a) It is closely related to stratification
b) It is literally paper thin
c) It is a layered structure developed in extremely fine grained igneous rocks
d) It is a layered structure developed in extremely fine grained sedimentary rocks
Answer: c
Clarification: The term lamination is closely related to stratification. It is a layered structure developed in extremely fine grained sedimentary rocks made up of clay and silt. The layers are paper thin literally speaking.
6. The maximum angle of inclination of a layer of a rock with the horizontal is _____________
a) Dip
b) Heave angle
c) Strike
d) Depth
Answer: a
Clarification: The definition of dip is “The maximum angle of inclination of a layer of a rock with the horizontal”. It is expressed both in terms of degree of inclination and direction of inclination.
7. Angle of dip is measured using which instrument?
a) Compass
b) Theodolite
c) Tacheometer
d) Clinometer
Answer: d
Clarification: The direction of dip is determined with a simple compass whereas the angle of dip is determined with an instrument called clinometer, which comes built in with the compass.
8. Which among the following is not a type of dip?
a) Widespread dip
b) Primary dip
c) Secondary dip
d) Local and regional dip
Answer: a
Clarification: The types of dips are primary, secondary, local and regional. Widespread dip is not considered as a dip.
9. The term “intrusion” is basically associated with which type of rock?
a) Igneous rock
b) Sedimentary rock
c) Metamorphic rock
d) Not associated with any type of rock
Answer: a
Clarification: Igneous rocks are formed from cooling and crystallization of hot molten material called magma/lava depending on the place of occurrence. The magma gets intruded or injected into the pre-existing rocks of any type- called the host rocks and takes variously shaped forms on cooling. These forms are commonly termed as Intrusion.
10. The dip which involves tectonic forces is _____________
a) Primary dip
b) Secondary dip
c) Local and Regional dip
d) No dip involves tectonic forces
Answer: b
Clarification: Secondary dip is the inclination induced in the strata after its deposition due to the tectonic forces to which such strata have been subsequently subjected. Secondary dips may range in value up to vertical.
11. 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
Answer: d
Clarification: 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
12. 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
Answer: c
Clarification: Vertical thickness = Width of outcrop * tan (angle of inclination)
Vertical thickness = 240 * tan (25°) = 111.91 m
13. 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
Answer: d
Clarification: 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.
14. 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
Answer: c
Clarification: 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.
15. 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
Answer: a
Clarification: 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.