This set of Engineering Geology Multiple Choice Questions & Answers (MCQs) focuses on “Metamorphism and their factors”.
1. What is the term used to express the process responsible for all the changes that take place in an original rock under the influence of changes?
Explanation: Metamorphism is the term used to express the process responsible for all the changes that take place in an original rock under the influence of changes in the surrounding conditions of temperature, pressure and chemically active fluids.
2. The factor not affecting metamorphism is
a) Wind conditions
d) Chemically active fluids
Explanation: The factors affecting the metamorphism of the rocks are temperature, pressure and chemically fluids. Wind conditions do not affect the metamorphism in any way.
3. Factors are also called
a) Primary aspects
b) Agents of metamorphism
c) Agents of changes
d) Tertiary aspects
Explanation: Metamorphic changes in the rocks are primarily the result of three main factors that are also sometimes called agents of metamorphism: heat, pressure and chemically active fluids.
4. The temperature up to which minerals in rocks are stable is
a) 100° C
b) 50° C
c) 500° C
d) 200° C
Explanation: Rocks are made up of minerals that are normally stable at temperature below 200° C. However, when the temperature around these rocks changes due to one reason or the other, the mineral composition of the rocks undergoes some changes.
5. Any given rock at some depth below the surface is subjected to pressure from how many sources?
Explanation: Any given rock at some depth below the surface is subjected to pressure from two sources: first, load of the overlying burden and second, from crustal movements.
6. What is the pressure exerted during the crustal movements called?
a) Indirect pressure
b) Directed pressure
c) Secondary pressure
d) Primary pressure
Explanation: The pressure from orogenic activity is generally lateral or horizontal and is commonly termed as directed pressure.
7. What is the direction of pressure exertion in load metamorphism?
d) Horizontal or inclined
Explanation: The load of the overlying burden acts generally exerts pressure in a vertical direction and the process of change in the structure of the rock is often referred as load metamorphism.
8. Pore fluids play important role metamorphism. State true or false.
Explanation: Presence or absence of chemically active fluids within the body of the rocks (the pore fluids) or around them plays very important role in the process of all types of metamorphism.
9. Water in which form is considered as single most important agent?
d) Solid and liquid
Explanation: Water in the form of steam is considered the single most important agent. The water may be present in the minerals as water of crystallization or simply as pore fluid or it may be supplied externally by magmatic bodies.
10. Which rocks show severe degree of metamorphism?
a) Situated near the plate boundaries
b) Situated inside the boundaries
c) Situated at the centre of the plates
d) Irrespective of the place, the degree is same everywhere
Explanation: Rocks situated near the plate boundaries or within the geosynclinal belts are especially prone to directed pressure and often show severest degree of metamorphic changes.
11. Metamorphism can also happen about 850° C. State true or false.
Explanation: It is believed that most metamorphic changes induced by the heat factor take place between 300°-850° C, some components of rock may actually start melting and hence rocks formed from their resolidification shall be included in the category of igneous rocks.
Sanfoundry Global Education & Learning Series – Engineering Geology.
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