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MEV-012: Earth Processes

MEV-012: Earth Processes

IGNOU Solved Assignment Solution for 2023-24

If you are looking for MEV-012 IGNOU Solved Assignment solution for the subject Earth Processes, you have come to the right place. MEV-012 solution on this page applies to 2023-24 session students studying in MSCENV courses of IGNOU.

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Assignment Code: MEV-012/TMA-01/January 2023 to July 2024 session

Course Code: MEV-012

Assignment Name: Earth Processes

Year: 2023-2024

Verification Status: Verified by Professor

Q1) Describe weathering and its types with suitable examples.

Ans) Weathering is the process by which rocks and minerals on or beneath the Earth's surface break down or disintegrate over time due to various physical, chemical, and biological factors. Weathering is a critical part of the rock cycle and plays a fundamental role in shaping landscapes and creating soil.

There are two main types of weathering: mechanical (physical) weathering and chemical weathering.

a) Mechanical (Physical) Weathering: Mechanical weathering involves the physical breakdown of rocks into smaller fragments without altering their chemical composition. This type of weathering occurs through various processes:

1) Frost Wedging: In regions with freeze-thaw cycles, water seeps into cracks in rocks. When this water freezes, it expands and exerts pressure on the surrounding rock, causing cracks to widen. Upon thawing, the cracks contract. Over time, this repeated freezing and thawing can fragment the rock. An example is the formation of potholes in road surfaces due to freeze-thaw cycles.

2) Exfoliation (Onion-Skin Weathering): This occurs when the outer layers of rocks peel away due to changes in pressure and release of stress. This often happens in regions with significant temperature variations. The repeated expansion and contraction of rocks cause outer layers to flake off, resembling the peeling of an onion.

3) Abrasion: Rocks can undergo abrasion when they rub against one another due to factors like wind, water, ice, or the movement of sediment. This process can result in the smoothing or rounding of rock surfaces. For example, riverbed rocks are often polished and rounded by the constant action of water and sediment.

4) Biological Activity: Plant roots and burrowing animals can exert pressure on rocks, causing them to crack and break apart. For instance, trees can push apart rocks as their roots expand, leading to the mechanical breakdown of rock material.

b) Chemical Weathering: Chemical weathering involves the alteration of the mineral composition of rocks through chemical reactions. Some common forms of chemical weathering include:

1) Hydration: This occurs when minerals in rocks absorb water molecules, leading to expansion and weakening of the rock. An example is the hydration of anhydrite to form gypsum, causing the rock to swell and crack.

2) Oxidation: Oxidation is the reaction of minerals with oxygen, often leading to a change in the color and composition of the rock. Iron-bearing minerals, such as pyrite (iron sulphide), can rust and turn into iron oxides.

3) Carbonation: Rainwater and carbon dioxide in the atmosphere can combine to form carbonic acid, which can dissolve certain minerals in rocks, particularly carbonates like limestone. Over time, carbonation can erode limestone formations.

4) Hydrolysis: Hydrolysis is a chemical reaction where water reacts with minerals to alter their structure. Silicate minerals in rocks are particularly susceptible to hydrolysis, causing them to break down into clay minerals. Granite, for example, can undergo hydrolysis to form clay minerals.

5) Biological Activity: In addition to mechanical weathering, some biological organisms, like lichens and certain bacteria, can produce acids that contribute to chemical weathering. These organisms release substances that break down minerals in rocks.

Both mechanical and chemical weathering processes often work in tandem to break down rocks, leading to the formation of sediments, soils, and the creation of distinctive landforms over geological time scales.

Q2) Explain the distribution of water in the earth’s crust and the hydrological cycle.

Ans) Distribution of Water in the Earth's Crust:

Water is an essential component of the Earth's crust, and it is found in various forms and locations. The distribution of water in the Earth's crust can be categorized as follows:

a) Surface Water: Surface water includes all the bodies of water found on the Earth's surface. This includes oceans, seas, rivers, lakes, and reservoirs. Oceans hold the vast majority of the Earth's surface water, accounting for about 97.5% of all water on Earth. The remaining 2.5% is freshwater, with most of it locked in glaciers and ice caps.

b) Groundwater: Groundwater is the water that is stored beneath the Earth's surface in aquifers, porous rock formations, and underground reservoirs. It accounts for a significant portion of the Earth's freshwater resources. Groundwater is a vital source of drinking water and is used for irrigation and industrial purposes.

c) Ice and Snow: Glaciers, ice caps, and permanent snow cover significant land areas, particularly in polar regions. These areas contain a substantial amount of freshwater in the form of ice and snow.

d) Soil Moisture: Water is also present in the upper layers of soil, where it is essential for plant growth and ecosystem health. Soil moisture can be variable and is influenced by factors like rainfall and evaporation.

e) Atmosphere: Water vapor is present in the Earth's atmosphere. While it represents a small fraction of the planet's water, it plays a crucial role in the hydrological cycle, as it can condense to form clouds and precipitation.

f) Biosphere: Water is a vital component of living organisms, and it is found in plants, animals, and microorganisms. The biosphere, including all living things, plays a role in the movement of water within the Earth's ecosystems.

The Hydrological Cycle:

The hydrological cycle, also known as the water cycle, is a continuous, natural process that describes the movement and circulation of water on Earth. It involves the following key stages:

a) Evaporation: The cycle begins with the heating of the Earth's surface, which causes water from oceans, rivers, lakes, and even the soil to evaporate into water vapor. This water vapor rises into the atmosphere.

b) Condensation: As the water vapor ascends into the cooler upper atmosphere, it condenses to form tiny water droplets, creating clouds. These clouds are composed of water in its liquid or ice form.

c) Precipitation: When the water droplets in clouds grow large enough, they fall to the Earth's surface as precipitation. Precipitation can take the form of rain, snow, sleet, or hail and provides a vital source of freshwater for terrestrial ecosystems.

d) Infiltration and Runoff: Precipitated water can follow two main paths. It can infiltrate into the ground, replenishing groundwater reserves, or it can flow over the surface as runoff, eventually making its way into rivers, lakes, and oceans.

e) Transpiration: Plants take up water from the soil through their roots and release it into the atmosphere through a process called transpiration. This contributes to the movement of water from the land into the atmosphere.

f) Sublimation: In regions with permanent ice and snow cover, some of the ice can change directly into water vapor without melting in a process called sublimation.

The hydrological cycle is a dynamic and interconnected system, and it plays a crucial role in maintaining the Earth's climate, shaping landscapes, and sustaining life on the planet. It continually redistributes water resources, ensuring that water is available for various natural and human activities.

Q3) Explain the terms hazard and disaster. Describe the types of hazards with examples.

Ans) Hazard and Disaster are two related but distinct concepts in the field of disaster management and risk assessment.


A hazard is a situation, condition, or event that has the potential to cause harm, loss, or adverse effects to people, property, the environment, or a combination of these. Hazards can be natural or human-made, and they are categorized into different types based on their origin and characteristics. Some common types of hazards include:

a) Natural Hazards

1) Geological Hazards: These hazards are associated with the Earth's geological processes. Examples include earthquakes, volcanic eruptions, landslides, and tsunamis.

2) Meteorological Hazards: These hazards are related to weather and atmospheric conditions. Examples include hurricanes, tornadoes, floods, and severe storms.

3) Hydrological Hazards: Hydrological hazards are linked to water-related events, such as river floods, flash floods, and dam failures.

4) Climatological Hazards: These hazards are connected to long-term climate patterns, including heatwaves, cold spells, and droughts.

5) Biological Hazards: Biological hazards involve the outbreak of diseases and health-related events, such as pandemics, epidemics, and insect-borne diseases.

b) Human-Made Hazards:

1) Technological Hazards: These hazards result from technological or industrial processes and include events like chemical spills, nuclear accidents, and industrial explosions.

2) Sociopolitical Hazards: These hazards are associated with human actions, such as civil unrest, terrorism, political conflicts, and social unrest.

3) Environmental Hazards: Environmental hazards are a result of environmental degradation, deforestation, soil erosion, pollution, and climate change.

4) Structural Hazards: Structural hazards pertain to the potential failure of buildings, infrastructure, or other man-made structures due to issues like poor construction, aging, or lack of maintenance.


A disaster is an event or situation characterized by significant and often widespread harm, damage, or disruption caused by the impact of a hazardous event. A disaster typically overwhelms the capacity of the affected community or region to cope with it using its available resources and response mechanisms. Disasters can result from the occurrence of one or more hazards and can have severe consequences, including loss of life, injuries, property damage, and long-lasting social and economic impacts.

a) Natural Disasters:

1) A massive earthquake that causes buildings to collapse, leading to casualties and infrastructure damage.

2) A hurricane with strong winds and heavy rainfall that causes flooding and wind-related damage to homes and communities.

3) A flash flood in a mountainous region that results in rapid water flow, sweeping away homes and causing loss of life.

b) Human-Made Disasters:

1) A nuclear power plant accident that releases radioactive materials into the environment, affecting human health and the environment.

2) A chemical spill from a factory that contaminates a nearby river, causing harm to aquatic life and affecting the local population.

3) A large-scale industrial explosion that results in fire, destruction, and injuries in the surrounding area.

Q4) Describe the various types man-made hazards and their impacts on humans.

Ans) Anthropogenic risks, often known as man-made hazards or simply hazards produced by human activity, negligence, or conduct, are dangers and threats that are caused by humans. An additional name for them is the term "anthropogenic dangers." These threats have the potential to have a significant detrimental effect, not only on the health and safety of humans but also on the natural environment. The perils that are a direct result of human activity can be classified into a few various types, each of which possesses its own unique characteristics as well as a unique set of potential implications. Here are some common types of man-made hazards and their impacts on humans

a) Technological Hazards:

1) Industrial Accidents: These include incidents like chemical spills, explosions in factories, and nuclear accidents. They can lead to injuries, deaths, environmental contamination, and long-term health effects due to exposure to hazardous substances.

2) Infrastructure Failures: The failure of critical infrastructure, such as bridges, dams, and levees, can result in loss of life, property damage, and disruption of essential services.

3) Transportation Accidents: Accidents involving various modes of transportation, including train derailments, plane crashes, and shipwrecks, can cause fatalities, injuries, and environmental pollution.

b) Sociopolitical Hazards:

1) Terrorism: Acts of terrorism, including bombings, shootings, and chemical or biological attacks, can result in loss of life, injuries, psychological trauma, and social disruption.

2) Civil Unrest: Civil unrest, such as riots, protests, and uprisings, can lead to violence, property damage, injuries, and disruptions to daily life.

3) Political Conflicts: Armed conflicts, wars, and military interventions can result in large-scale casualties, displacement of populations, and extensive infrastructure damage.

c) Environmental Hazards:

1) Pollution: Pollution from sources like industrial emissions, improper waste disposal, and chemical runoff can lead to health problems, including respiratory issues, waterborne diseases, and contamination of ecosystems.

2) Deforestation: The destruction of forests has far-reaching environmental consequences, such as habitat loss, biodiversity decline, soil erosion, and changes in local climates.

3) Climate Change: Activities like the burning of fossil fuels and deforestation contribute to global climate change, leading to more frequent and severe natural disasters, displacement of communities, and health risks.

d) Structural Hazards:

1) Building Failures: Poor construction practices, inadequate maintenance, or substandard materials can result in building collapses, posing risks to residents, workers, and passersby.

2) Bridge Failures: The failure of bridges can lead to accidents, injuries, and fatalities, affecting transportation and communities.

3) Infrastructure Aging: Aging infrastructure, such as water and sewage systems, can result in breakdowns, water contamination, and service disruptions.

e) Health-Related Hazards:

1) Epidemics and Pandemics: The spread of infectious diseases, such as COVID-19, can lead to widespread illness, hospitalizations, and fatalities.

2) Biological Threats: Deliberate release of biological agents, such as bioterrorism or accidental exposure to pathogens, can result in serious public health emergencies.

3) Food Safety Issues: Contamination of food products or unsafe food handling practices can lead to foodborne illnesses and health risks.

Q5) Give a detailed account on the physical, chemical, and biological aspects of sea water.

Ans) Sea water is a complex and dynamic environment that exhibits a wide range of physical, chemical, and biological characteristics. Understanding these aspects is crucial for various scientific disciplines, including oceanography, marine biology, and environmental science. Here's a detailed account of the physical, chemical, and biological aspects of sea water:

a) Physical Aspects:

1) Salinity: Salinity refers to the concentration of dissolved salts in sea water and is typically expressed in parts per thousand (ppt). The average salinity of seawater is around 35 ppt, but it can vary in different regions and depths. Salinity is influenced by factors such as evaporation, precipitation, and the mixing of fresh and saltwater.

2) Temperature: The temperature of sea water varies with depth, location, and season. Surface water temperatures can range from near freezing in polar regions to warm tropical waters. Temperature influences ocean circulation, climate, and the distribution of marine species.

3) Density: Sea water density is affected by temperature and salinity. Cold, salty water is denser and tends to sink, while warm, less salty water is less dense and rises. Density differences drive ocean currents and vertical circulation patterns.

4) Turbidity: Turbidity in sea water refers to the cloudiness or haziness caused by the presence of suspended particles, such as sediments, plankton, and organic matter. High turbidity can reduce light penetration and affect marine ecosystems.

5) Wave and Tidal Movements: Waves are created by wind, and tides are primarily caused by the gravitational pull of the moon and the sun. They play a crucial role in shaping coastal environments, influencing erosion, sediment transport, and providing nutrients.

b) Chemical Aspects:

1) pH: Sea water is slightly alkaline, with a pH of around 8.1 on average. However, pH can vary due to natural processes and human activities. Changes in pH, such as ocean acidification, can impact marine life, particularly calcifying organisms like corals and mollusks.

2) Dissolved Gases: Oxygen and carbon dioxide are the most important dissolved gases in sea water. Oxygen levels vary with temperature and depth, affecting marine organisms' respiration. Carbon dioxide levels influence oceanic acidity and play a role in the global carbon cycle.

3) Nutrients: Sea water contains essential nutrients, including nitrate, phosphate, and silicate. These nutrients are essential for the growth of marine phytoplankton and form the basis of the marine food web.

4) Trace Elements: Sea water contains trace elements, such as iron, manganese, and copper, which are vital for various biological processes. These elements can limit primary production in some ocean regions.

5) Salts: Sea water contains a wide range of dissolved salts, including sodium, chloride, magnesium, calcium, and sulphate. These salts influence sea water's properties, including its freezing point and electrical conductivity.

c) Biological Aspects:

1) Phytoplankton: Phytoplankton are microscopic, photosynthetic organisms that form the foundation of the marine food web. They play a vital role in carbon fixation, oxygen production, and nutrient cycling.

2) Zooplankton: Zooplankton are small, drifting animals that feed on phytoplankton and serve as a food source for higher trophic levels, including fish and marine mammals.

3) Marine Fauna: The diversity of marine fauna is vast, ranging from fish and marine mammals to invertebrates like corals and mollusks. Adaptations to the marine environment vary widely among species.

4) Benthic Communities: Benthic communities inhabit the ocean floor and include organisms like seafloor bacteria, worms, and sessile filter feeders. They play a crucial role in recycling nutrients and supporting pelagic ecosystems.

5) Marine Ecosystems: Sea water sustains a wide range of ecosystems, including coral reefs, kelp forests, estuaries, and deep-sea hydrothermal vents. Each ecosystem is characterized by unique biological communities and interactions.

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