75 Days Mains Revision Plan 2024 – World Geography
World Geography
Q1. What are the major tectonic plates involved in the formation of the Ring of Fire, and how do their movements affect seismic activity? 10M
Key demand of the question
Identify the major tectonic plates that contribute to the Ring of Fire and explain how their interactions and movements lead to significant seismic and volcanic activity.
Structure of the answer:
Introduction:
Introduce the Ring of Fire, noting its significance as a major area of volcanic and seismic activity encircling the Pacific Ocean. E.g. Taiwan Earthquake
Body:
- First mention the major tectonic plates involved in formation of ring of fire like pacific plate, north American plate, Eurasian plate etc.
- Afterwards mention how movements of these tectonic plates are responsible for the high levels of seismic activity in the Ring of Fire.
- Briefly mention its effect.
Conclusion
Highlight the importance of understanding these geological processes for disaster preparedness and risk mitigation.
Introduction
The Ring of Fire, also known as the Circum-Pacific Belt, is a horseshoe-shaped zone of intense seismic and volcanic activity that encircles the Pacific Ocean. This geologically active area is the result of plate tectonics, specifically the movement and interactions of several major and minor tectonic plates.
Body:
Tectonic plates involved in the formation of the Ring of Fire:
- Pacific Plate: The largest tectonic plate, it underlies the Pacific Ocean and is in constant motion, interacting with several other plates around its edges.
- North American Plate: This plate includes most of North America and part of the Atlantic Ocean. It interacts with the Pacific Plate along the western coast of North America.
- Eurasian Plate: Covers Europe and Asia, excluding India, the Arabian Peninsula, and the area east of the Chersky Range in Siberia. It interacts with the Pacific Plate to the east.
- Indo-Australian Plate: A major plate combining the Indian Plate and the Australian Plate, it interacts with the Pacific Plate to the northeast.
- South American Plate: Includes the continent of South America and part of the Atlantic Ocean. It interacts with the Pacific Plate along the western coast of South America.
- Nazca Plate: Located in the eastern Pacific Ocean, this plate interacts with the South American Plate.
- Philippine Sea Plate: Located east of the Philippines, it interacts with the Pacific Plate to the east.
- Cocos Plate: Located off the west coast of Central America, it interacts with the Pacific Plate and the North American Plate.
Movements and Seismic Activity: The movements of these tectonic plates are responsible for the high levels of seismic activity in the Ring of Fire:
- Subduction Zones: Many areas of the Ring of Fire are characterized by subduction zones, where one plate is forced below another. This process generates intense pressure and heat, leading to volcanic eruptions and earthquakes.
- g. the subduction of the Pacific Plate beneath the North American Plate (creating the Cascadia Subduction Zone) and the subduction of the Nazca Plate beneath the South American Plate (creating the Andes mountain range and associated volcanic activity).
- Transform Boundaries: At transform boundaries, plates slide past each other horizontally. The friction and stress from this movement can cause earthquakes.
- g. the San Andreas Fault in California, where the Pacific Plate and the North American Plate slide past each other.
- Divergent Boundaries: In some regions, plates move apart from each other, creating new crust as magma rises from below the Earth’s surface.
- While less common in the Ring of Fire, these boundaries can still contribute to volcanic activity and earthquakes.
- Plate Collisions: The collision of plates can also lead to significant seismic activity.
- For example, the collision of the Indian Plate with the Eurasian Plate has formed the Himalayan mountain range and caused frequent earthquakes in the region.
Conclusion
The complex interplay of these tectonic plates creates the dynamic and volatile nature of the Ring of Fire. This region is characterized by frequent earthquakes, volcanic eruptions, and the formation of deep ocean trenches and mountain ranges.
Q2. How do tropical and cold-water corals develop, and what anthropogenic factors have led to their deterioration? 15M
Key demand of the question
Explain the developmental processes of tropical and cold-water corals and to identify and analyze the human activities that have led to their deterioration.
Structure of the answer:
Introduction:
Introduce corals, mentioning their ecological importance and diversity. Briefly distinguish between tropical and cold-water corals.
Body:
- First, mention the conditions that are conducive for formation of tropical corals like tropical corals form in shallow, warm waters, primarily in the photic zone, their symbiotic relationship with zooxanthellae etc.
- Likewise mention the conditions for formation of cold water corals – develop in deeper, colder waters, often in the aphotic zone, lack of symbiotic algae, slower growth rates compared to tropical corals.
- Then, mention the anthropogenic factors that have led to their decline – climate change, pollution, destructive fishing practices, coral harvesting etc.
Conclusion
In conclusion, highlight the need for urgent action to mitigate anthropogenic impacts and to protect these vital marine ecosystems for future generations.
Introduction
Corals are invertebrate animals that belong to the Cnidaria phylum. They host algae called zooxanthellae within their tissues. Corals attach themselves to the ocean floor, much like plants rooting in the ground. This relationship with the algae enables corals to construct the world’s largest biological structures, the coral reefs, found in both tropical and cold ocean waters.
Body:
Development of Tropical Corals
- Location and Environment: Found in shallow, warm waters of the tropics, typically between 23°N and 23°S latitude. Prefer temperatures between 23-29°C.
- Require clear, sunlit waters to facilitate photosynthesis for their symbiotic algae (zooxanthellae).
- Formation Process: Coral polyps, tiny animals, secrete calcium carbonate to form hard skeletons.
- Symbiotic relationship with zooxanthellae: Polyps provide a home and carbon dioxide to the algae, which in return supply oxygen and organic compounds through
- Colonies grow as polyps divide and lay down new skeletal material, creating reef structures over thousands of years.
Cold-Water Corals
- Location and Environment: Found in deep, cold waters across the globe, including in the Arctic and Antarctic regions. Can thrive at depths ranging from 200 to over 2000 meters.
- Do not rely on sunlight, thus do not host symbiotic algae.
- Formation Process: Like tropical corals, cold-water corals secrete calcium carbonate to form their skeletons. They grow more slowly due to the colder, nutrient-rich waters.
- Form complex structures that provide habitats for various marine species.
Anthropogenic Factors Leading to Coral Deterioration:
- Ocean Warming: Elevated sea temperatures cause coral bleaching, where corals expel their symbiotic algae, leading to a loss of colour and essential nutrients.
- Prolonged bleaching can result in coral death.
- Ocean Acidification: Increased CO₂ absorption by oceans lowers pH levels, reducing the availability of carbonate ions needed for calcium carbonate skeleton formation, weakening corals.
- Pollution:
- Nutrient Runoff: Agricultural runoff containing fertilizers leads to algal blooms, which can smother corals and deplete oxygen in the water.
- Plastic Pollution: Corals ingest or get entangled in plastic waste, causing physical damage and introducing toxic substances.
- The Constitution permits state interference in the secular aspects of religion under certain conditions.
- Overfishing: Alters food webs and reduces the number of grazing fish, which helps control algal growth on corals. Blast fishing can also cause significant physical damage.
- Coral Harvesting: For the aquarium trade, jewellery, and curios can lead to overharvesting and habitat destruction.
Conclusion
Coral reefs are crucial for marine biodiversity, providing habitats for at least 25% of marine species. They also offer significant benefits to tourism, fisheries, and coastal protection. Therefore, their conservation is essential.
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