JNTU
JNTU B.Tech III GENERAL GEOLOGY Previous Question Paper (February/March - 2022 - R18)
Answer any five questions. All questions carry equal marks.
Main
Discuss the classification and global distribution of volcanoes and describe various volcanic products.
Answer
Volcanoes are classified based on their mode of eruption, frequency of activity, and morphology. By activity, they are categorized as active (erupting currently or recently), dormant (not erupted in historical time but expected to erupt again), and extinct (no longer expected to erupt). Morphologically, they are classified as shield volcanoes (broad, gently sloping, formed by low-viscosity basaltic lava), composite volcanoes or stratovolcanoes (steep-sided, formed by alternating layers of lava and pyroclastic material), and cinder cones (small, steep conical hills formed by ejected pyroclasts).
The global distribution of volcanoes is primarily controlled by plate tectonics. Most volcanoes are located along plate boundaries: the Circum-Pacific Belt (the Ring of Fire) associated with subduction zones, the Mid-Ocean Ridge system where divergent plate boundaries allow magma to rise, and intraplate hotspots such as Hawaii, which occur away from plate boundaries due to mantle plumes.
Volcanic products are classified into three main types:
- Lava flows: Molten rock that reaches the surface. Basaltic lava is fluid and travels long distances, while rhyolitic or andesitic lava is viscous and forms thick, short flows.
- Pyroclastic materials: Fragmented material ejected during explosive eruptions, ranging from fine volcanic ash and lapilli to large volcanic bombs and blocks.
- Volcanic gases: Primarily water vapor, carbon dioxide, sulfur dioxide, and hydrogen sulfide, which are released during eruptions and influence atmospheric conditions.
Explain the major discontinuities within the Earth’s interior.
Answer
The Earth's interior is divided into distinct layers based on seismic wave velocity changes, which occur at specific boundaries known as discontinuities:
- Conrad Discontinuity: Located within the upper crust, separating the upper granitic layer from the lower basaltic layer.
- Mohorovicic (Moho) Discontinuity: The boundary between the Earth's crust and the underlying mantle. It is marked by a significant increase in the velocity of P-waves and S-waves.
- Repetti Discontinuity: Situated within the mantle, separating the upper mantle from the lower mantle at a depth of approximately 650-670 km.
- Gutenberg Discontinuity: The boundary between the lower mantle and the outer core at a depth of about 2,900 km. S-waves are completely blocked here, indicating the outer core is in a liquid state.
- Lehmann Discontinuity: Located within the core, separating the liquid outer core from the solid inner core at a depth of approximately 5,150 km.
Give a brief account on soil erosion and conservation.
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Explain briefly about ‘Land forms? Why it is necessary in Geological consideration?
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What do you understand by paleochannels? Discuss briefly.
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Describe in brief about the types of landforms produced by Rivers.
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What is a volcano? Briefly describe elevated and depressed volcanic landforms.
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Briefly explain the secondary structures of sedimentary rocks with suitable diagram.
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Write the mineral composition, texture and petrological characteristics of conglomerate and shale.
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Describe with suitable sketches four different types of structures/textures found in metamorphic rocks and brief notes on their origin.
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What is paleontology and give their role in petroleum exploration?
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What is the importance of fossils in oil exploration?
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Explain briefly methods of preparation of organic walled microfossils.
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Describe in detail the significance of trace fossils.
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