Engineering Geology Questions and Answers – Classification of Sedimentary Rocks

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This set of Engineering Geology Multiple Choice Questions & Answers (MCQs) focuses on “Classification of Sedimentary Rocks”.

1. The process not contributing to clastic rocks is _____________
a) Weathering
b) Oxidation
c) Erosion
d) Deposition
View Answer

Answer: b
Explanation: The mechanically formed sedimentary rocks undergo processes like- weathering, erosion, transport, deposition and diagenesis. Oxidation is considered under to be a non-clastic cause.
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2. What is the size required for a particle to be called gravel?
a) Greater than 1 mm
b) Lesser 1 mm
c) Greater than 2 mm
d) Lesser than 1 mm
View Answer

Answer: c
Explanation: All sediments and clastic fragments of rocks above the size of 2 mm irrespective of their composition and shape are broadly termed as gravels.

3. What is not true about silts?
a) They are coarser than sand
b) They are finer than sand
c) They are further divided into fine, medium and fine silts
d) They are major constituents of shale
View Answer

Answer: a
Explanation: Silts are very fine-sized particles of varying composition lying in the range 1/16 mm and 1/256 mm. they are further divided into three categories, fine, medium and coarse. The silts are the major constituents of rocks known as shales.

4. What is the average grain size of rudaceous rocks?
a) Greater than 1 mm
b) Lesser 1 mm
c) Greater than 2 mm
d) Lesser than 1 mm
View Answer

Answer: c
Explanation: Rudites or rudaceous rocks include all coarse-grained rocks of heterogeneous composition. The average grain size of the constituents in rudites is greater than 2 mm.

5. Give an example for rudaceous rock.
a) Breccia
b) Shale
c) Limestone
d) Sandstone
View Answer

Answer: a
Explanation: In rudaceous rocks gravels are held together in the form of a rock by natural cementing material. Breccias and conglomerates are important examples of rudites.
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6. Rudites are also called as ____________
a) Arenites
b) Psamites
c) Lutites
d) Psephites
View Answer

Answer: d
Explanation: Rudites or rudaceous rocks are also called as psephites. Rudites are made up of boulders, cobbles and pebbles collectively known as gravels.

7. The arenaceous rocks have the grain size equal to ____________
a) Gravel
b) Sand
c) Silt
d) Clay
View Answer

Answer: b
Explanation: The arenites are also called as arenaceous rocks. These are made up of sediments of sand grade (2mm-1/16 mm).

8. An example for arenite would be ____________
a) Breccia
b) Shale
c) Limestone
d) Sandstone
View Answer

Answer: d
Explanation: In a particular rock, the sand grains of a particular size range may be predominating giving rise to coarse, medium and fine arenites. Sandstones, greywackes and arkoses are common types of arenites.

9. Which of the following are finest grain sized?
a) Rudaceous rocks
b) Arenaceous rocks
c) Argillaceous rocks
d) Psephites
View Answer

Answer: c
Explanation: Argillaceous rocks are also called as lutites. Lutites may be defined as sedimentary rocks of the finest grain-size. They are made up of silt and clay grades.
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10. A clastic rock might not have more than one grade.
a) True
b) False
View Answer

Answer: b
Explanation: Many times a clastic rock may be made of sediments of more than one grade. It is the dominant grade that is taken into consideration while classifying the rock.

11. Non-detrital rocks refer to ____________
a) Clastic rock
b) Non-clastic rock
c) Residual rock
d) None of the types
View Answer

Answer: b
Explanation:The non-clastic rocks are also called non-detrital rocks. They are generally homogeneous in character, fine-grained in particle size and varying in chemical composition.

12. Pick the type of sedimentary not belonging to chemically formed rocks.
a) Oxide rocks
b) Carbonaceous rocks
c) Ferruginous deposits
d) Siliceous deposits
View Answer

Answer: d
Explanation: The sedimentary rocks under the chemically formed deposits are Siliceous deposits, carbonate deposits, ferruginous, phosphatic and evaporites.

Sanfoundry Global Education & Learning Series – Engineering Geology.

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To practice all areas of Engineering Geology, here is complete set of 1000+ Multiple Choice Questions and Answers.

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Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He is Linux Kernel Developer & SAN Architect and is passionate about competency developments in these areas. He lives in Bangalore and delivers focused training sessions to IT professionals in Linux Kernel, Linux Debugging, Linux Device Drivers, Linux Networking, Linux Storage, Advanced C Programming, SAN Storage Technologies, SCSI Internals & Storage Protocols such as iSCSI & Fiber Channel. Stay connected with him @ LinkedIn