🌍 Conceptual Introduction (Rocks)
Rocks (igneous, sedimentary, metamorphic) form the foundation of Earth science MCQs in FPSC, CSS, PMS, and GAT examinations. Understanding classification, texture, and formation processes is essential for both theoretical and analytical questions.
Rocks are naturally occurring aggregates of minerals formed through geological processes such as magma cooling, sediment deposition, and metamorphism under heat and pressure.
One of the most important concepts is the rock cycle, which explains how any rock type can transform into another through Earth's internal and surface processes.
📌 In exams, focus on:
- ➤ Cooling rates → texture (fine vs coarse)
- ➤ Depositional environments → sedimentary rocks
- ➤ Pressure & temperature → metamorphic grade
- ➤ Rock transformations → rock cycle
👉 Key Insight: Focus on processes, not memorization — modern MCQs are concept-based.
Quick Navigation: Jump to any section instantly.
📚 Important Definitions
Understanding core terminology is essential for solving geology MCQs accurately in FPSC, CSS, PMS, and GAT exams. These definitions form the conceptual base for identifying rock types and interpreting geological processes.
🔥 Igneous Rocks
Rocks formed by the cooling and solidification of magma or lava.
🌍 Sedimentary Rocks
Rocks formed through deposition, compaction, and cementation of sediments.
⚡ Metamorphic Rocks
Rocks transformed due to heat, pressure, or chemically active fluids.
🔄 Rock Cycle
A continuous process through which rocks transform from one type to another.
📊 Foliation
Layered texture in metamorphic rocks caused by pressure alignment of minerals.
🌋 Rock Classification Table
Quick comparison for exams — memorize patterns, not just examples
| Rock Type | Formation Process | Texture | Common Examples |
|---|---|---|---|
| 🔥 Igneous | Cooling of magma or lava | Coarse or fine | Granite, Basalt |
| 🌍 Sedimentary | Deposition & cementation | Layered (strata) | Sandstone, Limestone |
| Heat & pressure alteration | Foliated / non-foliated | Marble, Slate |
⚠️ Examiner Trap Concepts
Examiners frequently design MCQs to confuse students using closely related concepts. Recognizing these traps can significantly improve your accuracy.
🚨 Warning: Most mistakes happen due to small conceptual misunderstandings!
Granite is intrusive, not extrusive.
Basalt is fine-grained due to rapid cooling.
Fossils are found only in sedimentary rocks.
Marble is non-foliated, despite being metamorphic.
Texture reflects cooling rate, not composition.
PART-1 — Rocks (Igneous, Sedimentary, Metamorphic) MCQs 1–10
1. Igneous rocks are formed by:
A. Cooling of molten magma
B. Compression of sediments
C. Biological accumulation
D. Chemical precipitation
Explanation:
Igneous rocks form when molten magma (below surface) or lava (above surface) cools and solidifies. Slow cooling underground produces coarse-grained rocks like granite, while rapid cooling at the surface forms fine-grained rocks like basalt. In exams, cooling rate is directly linked to crystal size, making this a frequently tested concept.
Igneous rocks form when molten magma (below surface) or lava (above surface) cools and solidifies. Slow cooling underground produces coarse-grained rocks like granite, while rapid cooling at the surface forms fine-grained rocks like basalt. In exams, cooling rate is directly linked to crystal size, making this a frequently tested concept.
2. Granite is classified as:
A. Intrusive igneous rock
B. Extrusive igneous rock
C. Sedimentary rock
D. Metamorphic rock
Explanation:
Granite forms below Earth’s surface with slow cooling producing large crystals, typical of intrusive rocks.
Granite forms below Earth’s surface with slow cooling producing large crystals, typical of intrusive rocks.
3. Fine-grained texture in igneous rocks indicates:
A. Rapid cooling
B. Slow cooling
C. High pressure metamorphism
D. Sediment compaction
Explanation:
Fine-grained texture indicates rapid cooling of lava at or near Earth’s surface. Because cooling happens quickly, crystals do not have enough time to grow large. This concept is important in distinguishing extrusive igneous rocks (fine-grained) from intrusive rocks (coarse-grained) in exam questions.
Fine-grained texture indicates rapid cooling of lava at or near Earth’s surface. Because cooling happens quickly, crystals do not have enough time to grow large. This concept is important in distinguishing extrusive igneous rocks (fine-grained) from intrusive rocks (coarse-grained) in exam questions.
4. Basalt is commonly:
A. Extrusive igneous rock
B. Sedimentary rock
C. Metamorphic rock
D. Organic rock
Explanation:
Basalt forms from lava cooling at the surface therefore belongs to extrusive igneous rocks.
Basalt forms from lava cooling at the surface therefore belongs to extrusive igneous rocks.
5. Layered structure is typical of:
A. Sedimentary rocks
B. Igneous rocks
C. Intrusive rocks
D. Lava glass
Explanation:
Sedimentary rocks typically form in layers called strata due to the gradual deposition of sediments over time. These layers often preserve fossils and provide clues about past environments. In exams, layering (bedding) is a key identifying feature of sedimentary rocks.
Sedimentary rocks typically form in layers called strata due to the gradual deposition of sediments over time. These layers often preserve fossils and provide clues about past environments. In exams, layering (bedding) is a key identifying feature of sedimentary rocks.
6. Sandstone forms by:
A. Compaction and cementation
B. Lava cooling
C. Metamorphism of granite
D. Chemical crystallization
Explanation:
Clastic sedimentary rocks like sandstone form from compressed and cemented sand particles.
Clastic sedimentary rocks like sandstone form from compressed and cemented sand particles.
7. Metamorphic rocks form due to:
A. Heat and pressure
B. Cooling magma
C. Deposition
D. Evaporation
Explanation:
Existing rocks change mineral structure under temperature and pressure forming metamorphic rocks.
Existing rocks change mineral structure under temperature and pressure forming metamorphic rocks.
8. Marble originates from:
A. Limestone
B. Granite
C. Basalt
D. Sandstone
Explanation:
Limestone recrystallizes under metamorphism forming marble, an example of rock transformation.
Limestone recrystallizes under metamorphism forming marble, an example of rock transformation.
9. Slate develops from:
A. Shale
B. Sandstone
C. Granite
D. Basalt
Explanation:
Low grade metamorphism converts shale into slate producing fine foliation.
Low grade metamorphism converts shale into slate producing fine foliation.
10. Fossils are commonly found in:
A. Sedimentary rocks
B. Igneous rocks
C. Metamorphic rocks
D. Lava rocks
Explanation:
Fossils are commonly found in sedimentary rocks because they form under low temperature and pressure conditions that preserve biological remains. In contrast, igneous and metamorphic processes usually destroy fossils due to extreme heat.
Fossils are commonly found in sedimentary rocks because they form under low temperature and pressure conditions that preserve biological remains. In contrast, igneous and metamorphic processes usually destroy fossils due to extreme heat.
PART-2 — Rocks (Igneous, Sedimentary, Metamorphic) MCQs 11–20
11. Obsidian forms due to:
A. Extremely rapid cooling of lava
B. Slow underground cooling
C. Sediment deposition
D. Regional metamorphism
Explanation:
Obsidian has a glassy texture because lava cools so rapidly that crystals cannot form in igneous rocks.
Obsidian has a glassy texture because lava cools so rapidly that crystals cannot form in igneous rocks.
12. Pumice is characterized by:
A. Vesicular texture with gas bubbles
B. Coarse crystals
C. Foliated layers
D. Cemented sand grains
Explanation:
Pumice forms when gas escapes during lava cooling producing vesicles, a diagnostic igneous rock texture.
Pumice forms when gas escapes during lava cooling producing vesicles, a diagnostic igneous rock texture.
13. Conglomerate is classified as:
A. Clastic sedimentary rock
B. Chemical sedimentary rock
C. Igneous rock
D. Metamorphic rock
Explanation:
Conglomerate forms from rounded gravel particles cemented together indicating transport and deposition processes.
Conglomerate forms from rounded gravel particles cemented together indicating transport and deposition processes.
14. Rock salt is formed by:
A. Evaporation of saline water
B. Magma cooling
C. Heat and pressure
D. Volcanic eruption
Explanation:
Evaporite sedimentary rocks such as rock salt form when dissolved minerals crystallize during evaporation.
Evaporite sedimentary rocks such as rock salt form when dissolved minerals crystallize during evaporation.
15. Coal forms from:
A. Accumulated plant remains
B. Cooling lava
C. Metamorphism of granite
D. Crystallization of minerals
Explanation:
Organic sedimentary rocks develop from buried plant material undergoing compaction over geological time.
Organic sedimentary rocks develop from buried plant material undergoing compaction over geological time.
16. Quartzite forms from metamorphism of:
A. Sandstone
B. Limestone
C. Shale
D. Granite
Explanation:
Sandstone recrystallizes under metamorphism forming quartzite, a non-foliated metamorphic rock.
Sandstone recrystallizes under metamorphism forming quartzite, a non-foliated metamorphic rock.
17. Gneiss texture indicates:
A. High-grade metamorphism
B. Rapid cooling
C. Sediment deposition
D. Chemical precipitation
Explanation:
Banded mineral arrangement in gneiss develops under intense heat and pressure during metamorphism.
Banded mineral arrangement in gneiss develops under intense heat and pressure during metamorphism.
18. The parent rock of slate is:
A. Shale
B. Sandstone
C. Basalt
D. Granite
Explanation:
Slate develops by low-grade metamorphism of shale producing fine foliation planes.
Slate develops by low-grade metamorphism of shale producing fine foliation planes.
19. Which rock is foliated?
A. Schist
B. Marble
C. Quartzite
D. Basalt
Explanation:
Schist displays aligned mineral layers produced by directed pressure during metamorphism.
Schist displays aligned mineral layers produced by directed pressure during metamorphism.
20. The rock cycle explains:
A. Transformation between rock types
B. Only formation of igneous rocks
C. Only sediment deposition
D. Only weathering processes
Explanation:
The rock cycle explains how rocks continuously transform between igneous, sedimentary, and metamorphic types through processes such as melting, cooling, weathering, and metamorphism. This concept is central in exams and often appears in conceptual or diagram-based MCQs.
The rock cycle explains how rocks continuously transform between igneous, sedimentary, and metamorphic types through processes such as melting, cooling, weathering, and metamorphism. This concept is central in exams and often appears in conceptual or diagram-based MCQs.
PART-3 — Rocks (Igneous, Sedimentary, Metamorphic) MCQs 21–30
21. Porphyritic texture indicates:
A. Two-stage cooling history
B. Uniform slow cooling
C. Sediment compaction
D. Metamorphic foliation
Explanation:
Large crystals form during slow cooling followed by rapid cooling of magma producing porphyritic igneous rocks.
Large crystals form during slow cooling followed by rapid cooling of magma producing porphyritic igneous rocks.
22. Diorite is compositionally intermediate between:
A. Granite and basalt
B. Sandstone and shale
C. Marble and quartzite
D. Coal and limestone
Explanation:
Diorite contains minerals intermediate between felsic granite and mafic basalt in igneous rock classification.
Diorite contains minerals intermediate between felsic granite and mafic basalt in igneous rock classification.
23. Shale forms mainly from:
A. Clay-sized particles
B. Gravel fragments
C. Lava fragments
D. Chemical crystals only
Explanation:
Shale is a fine-grained clastic sedimentary rock formed from compacted clay particles.
Shale is a fine-grained clastic sedimentary rock formed from compacted clay particles.
24. Limestone commonly forms in:
A. Marine environments
B. Volcanic vents
C. Desert lava flows
D. Deep mantle zones
Explanation:
Limestone accumulates from shells and calcium carbonate in shallow seas indicating depositional environment.
Limestone accumulates from shells and calcium carbonate in shallow seas indicating depositional environment.
25. Chalk is composed primarily of:
A. Microfossil shells
B. Volcanic ash
C. Sand grains
D. Iron oxides
Explanation:
Chalk is a biochemical sedimentary rock made of microscopic marine organism shells.
Chalk is a biochemical sedimentary rock made of microscopic marine organism shells.
26. Contact metamorphism occurs due to:
A. Heat from nearby magma
B. Surface weathering
C. River transport
D. Ocean evaporation
Explanation:
Rocks adjacent to magma bodies recrystallize due to high temperature forming contact metamorphic rocks.
Rocks adjacent to magma bodies recrystallize due to high temperature forming contact metamorphic rocks.
27. Regional metamorphism is associated with:
A. Mountain building processes
B. River deposition
C. Volcanic ash fall
D. Wind erosion
Explanation:
Large-scale pressure and temperature during tectonic activity produces regional metamorphic rocks.
Large-scale pressure and temperature during tectonic activity produces regional metamorphic rocks.
28. Marble texture is:
A. Non-foliated crystalline
B. Vesicular
C. Clastic layered
D. Glassy
Explanation:
Marble recrystallizes into interlocking calcite crystals without layering in metamorphic rocks.
Marble recrystallizes into interlocking calcite crystals without layering in metamorphic rocks.
29. The parent rock of quartzite is:
A. Sandstone
B. Limestone
C. Basalt
D. Shale
Explanation:
Sandstone recrystallizes under metamorphism forming hard quartzite rock.
Sandstone recrystallizes under metamorphism forming hard quartzite rock.
30. Hornfels is produced by:
A. Contact metamorphism
B. Sediment compaction
C. Lava eruption
D. Weathering
Explanation:
Hornfels forms when surrounding rocks bake near magma intrusion under high temperature.
Hornfels forms when surrounding rocks bake near magma intrusion under high temperature.
PART-4 — Rocks (Igneous, Sedimentary, Metamorphic) MCQs 31–40
31. A rock formed from volcanic ash is:
A. Tuff
B. Granite
C. Marble
D. Quartzite
Explanation:
Tuff forms when volcanic ash particles are compacted and cemented, representing pyroclastic igneous rocks.
Tuff forms when volcanic ash particles are compacted and cemented, representing pyroclastic igneous rocks.
32. Vesicular basalt indicates:
A. Escape of gas during cooling
B. High sediment pressure
C. Regional metamorphism
D. Chemical precipitation
Explanation:
Vesicles form when dissolved gases escape from lava as it solidifies in extrusive igneous rocks.
Vesicles form when dissolved gases escape from lava as it solidifies in extrusive igneous rocks.
33. Breccia differs from conglomerate because fragments are:
A. Angular
B. Rounded
C. Fine-grained
D. Crystalline
Explanation:
Breccia contains angular rock fragments indicating short transport before deposition in sedimentary rocks.
Breccia contains angular rock fragments indicating short transport before deposition in sedimentary rocks.
34. Rock formed from evaporation of gypsum solution is:
A. Chemical sedimentary rock
B. Igneous rock
C. Metamorphic rock
D. Organic sedimentary rock
Explanation:
Evaporite rocks form when dissolved minerals crystallize from evaporating water bodies.
Evaporite rocks form when dissolved minerals crystallize from evaporating water bodies.
35. Bituminous coal is produced by:
A. Increased burial and pressure
B. Lava cooling
C. Metamorphism of granite
D. Ocean evaporation
Explanation:
Progressive burial transforms peat into lignite and then bituminous coal in sedimentary rock processes.
Progressive burial transforms peat into lignite and then bituminous coal in sedimentary rock processes.
36. Index minerals are useful for determining:
A. Metamorphic grade
B. Sediment size
C. Cooling rate
D. Fossil age only
Explanation:
Minerals like garnet and kyanite indicate temperature and pressure conditions of metamorphic rocks.
Minerals like garnet and kyanite indicate temperature and pressure conditions of metamorphic rocks.
37. Schistosity develops due to:
A. Alignment of platy minerals
B. Rapid cooling
C. Cementation
D. Chemical precipitation
Explanation:
Schistosity forms when minerals align perpendicular to pressure during metamorphism.
Schistosity forms when minerals align perpendicular to pressure during metamorphism.
38. Migmatite represents:
A. Partial melting during metamorphism
B. Sediment compaction
C. Pure igneous rock
D. Chemical sedimentary rock
Explanation:
Migmatite represents a transitional rock showing both metamorphic and igneous features due to partial melting. It forms under extreme temperature conditions where rocks begin to melt but not completely. This is a high-level concept frequently tested in CSS and PMS exams.
Migmatite represents a transitional rock showing both metamorphic and igneous features due to partial melting. It forms under extreme temperature conditions where rocks begin to melt but not completely. This is a high-level concept frequently tested in CSS and PMS exams.
39. Amphibolite forms mainly from metamorphism of:
A. Basalt
B. Limestone
C. Sandstone
D. Coal
Explanation:
Mafic igneous rocks like basalt transform into amphibolite under regional metamorphism.
Mafic igneous rocks like basalt transform into amphibolite under regional metamorphism.
40. The rock cycle demonstrates that:
A. Rocks continuously change type
B. Only igneous rocks transform
C. Sedimentary rocks are permanent
D. Metamorphic rocks cannot melt
Explanation:
Geological processes allow igneous, sedimentary and metamorphic rocks to convert into one another.
Geological processes allow igneous, sedimentary and metamorphic rocks to convert into one another.
PART-5 — Rocks (Igneous, Sedimentary, Metamorphic) MCQs 41–50
41. Andesite is typically formed in:
A. Volcanic arcs at convergent boundaries
B. Mid-ocean ridges only
C. Desert basins
D. Deep ocean trenches only
Explanation:
Andesite commonly forms where oceanic plates subduct beneath continental plates producing intermediate magma.
Andesite commonly forms where oceanic plates subduct beneath continental plates producing intermediate magma.
42. Coquina is composed mainly of:
A. Shell fragments
B. Lava fragments
C. Clay particles
D. Iron minerals
Explanation:
Coquina is a biochemical sedimentary rock formed from cemented shell debris in marine environments.
Coquina is a biochemical sedimentary rock formed from cemented shell debris in marine environments.
43. Anthracite represents:
A. Highest grade coal
B. Lowest grade coal
C. Igneous rock
D. Chemical sediment
Explanation:
Anthracite forms under higher pressure and temperature indicating advanced coal metamorphism.
Anthracite forms under higher pressure and temperature indicating advanced coal metamorphism.
44. Metaconglomerate forms when conglomerate undergoes:
A. Metamorphism
B. Rapid cooling
C. Evaporation
D. Cementation only
Explanation:
Existing sedimentary rocks change into metamorphic rocks when subjected to heat and pressure.
Existing sedimentary rocks change into metamorphic rocks when subjected to heat and pressure.
45. Eclogite forms under:
A. Very high pressure
B. Surface cooling
C. Low temperature only
D. River deposition
Explanation:
Eclogite is a high-pressure metamorphic rock typically formed in subduction zones deep within Earth.
Eclogite is a high-pressure metamorphic rock typically formed in subduction zones deep within Earth.
Figure: High-pressure metamorphic rock showing garnet-pyroxene texture.
46. Pegmatite is characterized by:
A. Very large crystals
B. Fine glassy texture
C. Layered bedding
D. Fossil fragments
Explanation:
Pegmatite forms from late-stage magma cooling slowly allowing exceptionally large mineral crystals.
Pegmatite forms from late-stage magma cooling slowly allowing exceptionally large mineral crystals.
47. Laterite forms in:
A. Tropical weathering environments
B. Deep ocean basins
C. Volcanic vents
D. Polar glaciers
Explanation:
Laterite is a residual sedimentary rock formed by intense chemical weathering in warm humid climates.
Laterite is a residual sedimentary rock formed by intense chemical weathering in warm humid climates.
48. Greenschist facies indicates:
A. Low-grade metamorphism
B. High-temperature melting
C. Sediment deposition
D. Igneous crystallization
Explanation:
Greenschist facies minerals develop under moderate temperature and pressure during early metamorphism.
Greenschist facies minerals develop under moderate temperature and pressure during early metamorphism.
49. Arkose sandstone contains abundant:
A. Feldspar grains
B. Shell fragments
C. Iron oxide layers
D. Volcanic glass
Explanation:
Arkose forms near granitic sources where feldspar grains have not been fully weathered.
Arkose forms near granitic sources where feldspar grains have not been fully weathered.
50. The rock cycle ultimately depends on:
A. Earth’s internal and surface processes
B. Only volcanic eruptions
C. Only sedimentation
D. Only metamorphism
Explanation:
Heat, pressure, weathering and erosion collectively drive transformation among all rock types.
Heat, pressure, weathering and erosion collectively drive transformation among all rock types.
💡 Concept Reminder
Every rock tells a geological story.
Identifying the formation process
is the key to solving most exam questions correctly.
⚡ 5-Second Revision Flashcards
🌋 What forms igneous rocks?
Cooling of magma or lava
⏱️ What controls texture?
Cooling rate
🔥 Fast cooling = ?
Fine-grained texture
🐢 Slow cooling = ?
Coarse-grained texture
🌍 Where are fossils found?
Sedimentary rocks
⚡ What forms metamorphic rocks?
Heat & pressure
📊 What is foliation?
Mineral alignment due to pressure
🔄 What is rock cycle?
Transformation of all rock types
🌋 Granite type?
Intrusive igneous
🌋 Basalt type?
Extrusive igneous
🎯 Key Takeaways
- Rocks are classified based on formation process
- Texture indicates cooling or pressure conditions
- Sedimentary rocks preserve fossils
- Rock cycle explains transformation of all rocks
📘 Concluding Analytical Perspective
The study of rocks extends beyond simple classification; it reveals Earth’s dynamic processes and geological history. In competitive exams, success depends on connecting
texture,
formation, and
transformation rather than relying on memorization.
Candidates who develop a process-based understanding of igneous, sedimentary, and metamorphic rocks can solve both conceptual and analytical MCQs with greater accuracy and confidence.
❓ Frequently Asked Questions
What is the rock cycle?
The rock cycle is a continuous process where rocks transform between igneous, sedimentary, and metamorphic forms.
Why are fossils found in sedimentary rocks?
Sedimentary rocks form under low-temperature conditions, allowing preservation of biological remains.
What is the difference between intrusive and extrusive rocks?
Intrusive rocks cool slowly beneath Earth's surface, while extrusive rocks cool rapidly at the surface.
What is foliation?
Foliation is the alignment of minerals in metamorphic rocks due to pressure.
Disclaimer: These MCQs are created for educational and practice purposes only.
About the Author: This content is prepared by an academic MCQs specialist for competitive exam preparation.
Last Updated: March 22, 2026
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