UGC NET Environmental Science Unit-IV: Environmental Geosciences Syllabus

Unit-IV: Environmental Geosciences syllabus — full chapter and topic list

Expand any chapter to see its topics and sub-topics. This is the whole examinable outline for Unit-IV: Environmental Geosciences in UGC NET Environmental Science, not a summary of it.

1. 1

   Origin of Earth and Geochemical Differentiation

   3 topics

   • Primary geochemical differentiation and formation of core, mantle, crust, atmosphere and hydrosphere
   • Concept of minerals and rocks
   • Formation of igneous and metamorphic rocks
2. 2

   Landforms and Earth's Energy Budget

   6 topics

   • Controls on formation of landforms - tectonic including plate tectonic and climatic
   • Concept of steady state and equilibrium
   • Energy budget of the earth
   • Earth’s thermal environment and seasons
   • Coriolis force, pressure gradient force, frictional force, geo-strophic wind field, gradient wind
   • Climates of India, western disturbances, Indian monsoon, droughts, El Nino, La Nina
3. 3

   Natural Cycles and Weathering

   7 topics

   • Concept of residence time and rates of natural cycles
   • Geophysical fields
   • Weathering including weathering reactions, erosion, transportation and deposition of sediments
   • Soil forming minerals and process of soil formation
   • Identification and characterization of clay minerals
   • Soil physical and chemical properties, soil types and climate control on soil formation
   • Cation exchange capacity and mineralogical controls
4. 4

   Geochemical Processes and Water Distribution

   7 topics

   • Geochemical classification of elements, abundance of elements in bulk earth, crust, hydrosphere and biosphere
   • Partitioning of elements during surficial geologic processes, Geochemical recycling of elements
   • Paleoclimate
   • Distribution of water in earth, hydrology and hydrogeology, major basins and groundwater provinces of India
   • Darcy’s law and its validity, groundwater fluctuations, hydraulic conductivity, groundwater tracers
   • Land subsidence, effects of excessive use of groundwater, groundwater quality
   • Pollution of groundwater resources, Ghyben-Herzberg relation between fresh-saline water
5. 5

   Resource Exploration and Hazards

   4 topics

   • Natural resource exploration and exploitation and related environmental concerns
   • Historical perspective and conservation of non-renewable resources
   • Natural Hazards: Catastrophic geological hazards - floods, landslides, earthquakes, volcanism, avalanche, tsunami and cloud bursts
   • Prediction of hazards and mitigation of their impacts

Unit-IV: Environmental Geosciences flashcards for UGC NET Environmental Science

21 of 67 cards from the Unit-IV: Environmental Geosciences deck — real questions with worked answers.

1. What is primary geochemical differentiation of the Earth?

   The early process by which the initially homogeneous molten Earth separated into chemically distinct layers (core, mantle, crust) and degassed to form the atmosphere and hydrosphere, driven by density differences and gravity.

2. How did the Earth's core form, and what is its dominant composition?

   Dense molten iron-nickel sank to the centre during the 'iron catastrophe' (gravitational settling of metals), forming a Fe-Ni core with a solid inner core and liquid outer core.

3. What is a mineral?

   A naturally occurring, inorganic, homogeneous solid with a definite (or limited-range) chemical composition and an ordered internal crystalline (atomic) structure.

4. What is a rock?

   A naturally occurring solid aggregate of one or more minerals (or mineraloids) that forms a significant part of the Earth's crust.

5. How are igneous rocks formed, and what distinguishes intrusive from extrusive types?

   They form by cooling and solidification of magma/lava. Intrusive (plutonic) rocks cool slowly underground giving coarse grains (e.g., granite); extrusive (volcanic) rocks cool rapidly at the surface giving fine grains (e.g., basalt).

6. How are metamorphic rocks formed?

   By transformation of pre-existing rocks in the solid state through heat, pressure, and chemically active fluids, producing new mineral assemblages and textures (e.g., shale to slate, limestone to marble).

7. What are the two main controls on the formation of landforms?

   Tectonic (including plate tectonic) controls and climatic controls; endogenic forces build relief while exogenic/climatic processes sculpt it.

8. What are the three types of plate boundaries and an example landform of each?

   Divergent (mid-ocean ridges, rift valleys), convergent (mountains, trenches, volcanic arcs), and transform (fault zones such as the San Andreas Fault).

9. What is the concept of steady state in earth systems?

   A condition in which the inputs and outputs of a system are balanced so that the state variables (mass, energy) remain constant over time, even though material continuously flows through.

10. How does equilibrium differ from steady state?

    In true equilibrium there is no net flux and the system is at minimum energy/maximum entropy with no work; in steady state there is continuous throughput of matter/energy but constant storage.

11. What is the Earth's energy budget?

    The balance between incoming solar (shortwave) radiation absorbed by the Earth-atmosphere system and the outgoing longwave (terrestrial) radiation; over the long term these are equal, giving a stable mean temperature.

12. Approximately what is the Earth's average planetary albedo?

    About 30% (0.30) of incoming solar radiation is reflected back to space by clouds, aerosols, and the surface.

13. What value is the solar constant?

    About 1361-1366 W/m² (commonly cited ~1.36 kW/m²), the mean solar irradiance received at the top of the atmosphere on a surface perpendicular to the Sun's rays.

14. Why does the Earth experience seasons?

    Because of the tilt of the Earth's rotational axis (~23.5°) relative to its orbital plane, which changes the angle and duration of solar insolation at a given latitude over the year (not the varying Earth-Sun distance).

15. What is the Coriolis force and how does it deflect winds in each hemisphere?

    An apparent (pseudo) force due to Earth's rotation that deflects moving air to the right in the Northern Hemisphere and to the left in the Southern Hemisphere; it is zero at the equator and maximum at the poles.

16. What is the pressure gradient force (PGF)?

    The force that drives air from high to low pressure; it acts perpendicular to isobars and is the primary force initiating horizontal wind, with magnitude proportional to the pressure gradient.

17. What is geostrophic wind?

    A theoretical steady horizontal wind that blows parallel to straight isobars when the pressure gradient force is exactly balanced by the Coriolis force (above the friction layer).

18. What is gradient wind?

    Wind that flows along curved isobars where the pressure gradient force, Coriolis force, and centripetal (centrifugal) acceleration are balanced; it accounts for curvature around highs and lows.

19. How does frictional force affect surface wind direction?

    Friction with the surface reduces wind speed, weakening the Coriolis force, so surface winds cross the isobars at an angle blowing from high toward low pressure rather than parallel to them.

20. What are western disturbances and their significance for India?

    Extratropical low-pressure systems originating over the Mediterranean/Caspian region that travel eastward and bring winter rain and snow to northwest India, crucial for rabi (winter) crops like wheat.

21. What causes the Indian monsoon?

    Differential heating of land and sea creating a low-pressure zone over the Indian subcontinent in summer, reversing the pressure gradient and drawing moisture-laden southwest winds; the seasonal reversal of wind direction defines the monsoon.

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