ANSWER WRITING_1

1.Discuss the major soils of India. Critically evaluate the role of the Soil Health Card in the context of the changing pattern of cultivation.(250 words/15 Marks)

1. Introduce the importance of soil and fertility in India. (50 words)

2. Elaborate the major soils in India. (100 words)

3. Explain the role of the Soil Health Card. (50 words)

4. Write a brief conclusion stating its benefits and uses. (50 words)

 

Soil is the most important layer of the earth’s crust. It is a valuable resource. The bulk of our food and much of our clothing is derived from land-based crops that grow in the soil. The soil on which we depend so much for our day-to-day needs has evolved over thousands of years. Soil Health Card has a key role to enhance the land use and better crop pattern in the region.

 

India has varied relief features, landforms, climatic realms and vegetation types. These have contributed to the development of major soils in India, which are:

                                                       Fig: Soils of India

 

• Alluvial soils are widespread in the northern plains and the river valleys. It covers about 40% of the total area of the country. They are depositional soils, transported and deposited by rivers and streams. They are generally rich in potash but poor in phosphorous. In the Upper and Middle Ganga plain, two different types of alluvial soils have developed, viz. Khadar and Bhangar. Khadar is the new alluvium and is deposited by floods annually, which enriches the soil by depositing fine silts. Bhangar represents a system of older alluvium, deposited away from the flood plains. Both the Khadar and Bhangar soils contain calcareous concretions (Kankars).

 

• Black soil covers most of the Deccan Plateau which includes parts of Maharashtra, Madhya Pradesh, Gujarat, Andhra Pradesh, and some parts of Tamil Nadu. These soils are also known as the ‘Regur Soil’ or the ‘Black Cotton Soil’. The black soils are generally clayey, deep, and impermeable. They swell and become sticky when wet and shrink when dried. So, during the dry season, these soil develop wide cracks. Thus, they are also known as ‘self-ploughing’ soil.

 

• Red and Yellow Soil develops on crystalline igneous rocks in areas of low rainfall in the eastern and southern part of the Deccan Plateau. The soil develops a reddish colour due to a wide diffusion of iron in crystalline and metamorphic rocks. It looks yellow when it occurs in a hydrated form. They are generally poor in nitrogen, phosphorous, and humus.

 

• Laterite Soil Laterite has been derived from the Latin word ‘Later’ which means brick. The laterite soils develop in areas with high temperature and high rainfall. With rain, lime and silica are leached away, and soils rich in iron oxide and aluminium compound are left behind. Hence, laterites are not suitable for cultivation; however, the application of manures and fertilisers are required for making the soils fertile for cultivation.

 

• Arid Soils range from red to brown in colour. They are generally sandy in structure and saline in nature. Due to the dry climate, high temperature, and accelerated evaporation, they lack moisture and humus. When irrigation is made available, the soil moisture is readily available for sustainable plant growth. Arid soils are characteristically developed in western Rajasthan, which exhibits characteristic arid topography. These soils are poor and contain little humus and organic matter.

 

• Forest Soils are formed in the forest areas where sufficient rainfall is available. The soils vary in structure and texture depending on the mountain environment where they are formed. They are loamy and silty on valley sides and coarse-grained in the upper slopes. In the snow-bound areas of the Himalayas, they experience denudation and are acidic with low humus content. The soils found in the lower valleys are fertile.

 

2.The Ring of Fire is home to over more than 450 volcanoes and is affected by 90% of the earthquakes”. Discuss the formation of the Ring of Fire due to plate tectonics.(250 words/15 Marks)

Approach

1. Introduce the Ring of Fire by stating its location, shape, and characteristics. (20 words)

2. Discuss the formation of the Pacific Ring of Fire. (70 words)

3. Give some of the important geological features associated with it. (30 words)

4. Conclude by explaining the reason behind its active state due to which it hosts the largest number of active volcanoes of the world. (30 words)

The Ring of Fire is also referred to as the Circum-Pacific Belt. It is a path along the Pacific Ocean characterized by active volcanoes and frequent earthquakes. The majority of Earth’s volcanoes and earthquakes take place along the Ring of Fire. It comprises of 450 volcanoes and 90% of the earthquakes are recorded here. Three of four the world’s most active volcanoes such as Mt. Fuji of Japan, Mt. St. Helens of the USA, and Mt. Pinatubo of Philippines are located in it. Its length is approximately 40,000 kilometres and is horseshoe-shaped. It is entirely located in the Pacific ocean.

 

                                                      Fig: RING of FIRE

   

Formation of the Pacific Ring of Fire

• The Pacific Ring of Fire traces boundaries between several tectonic plates—including the Pacific, Juan de Fuca, Cocos, Indian-Australian, Nazca, North American, and Philippine Plates.

• The abundance of volcanoes and earthquakes along the Ring of Fire is caused by the amount of movement of tectonic plates in the area. Along much of the Ring of Fire, plates overlap at convergent boundaries called subduction zones.

• The plate that is underneath is pushed down, or subducted, by the plate above. As the rock is subducted, it melts and becomes magma.

• The abundance of magma so near to Earth’s surface gives rise to conditions ripe for volcanic activity. A significant exception is the border between the Pacific and North American Plates.

• This stretch of the Ring of Fire is a transform boundary, where plates move sideways past one another. This type of boundary generates a large number of earthquakes as tension in Earth’s crust builds up and is released.

• Series of volcanic eruption across the pacific ocean forms a horseshoe-shaped structure known as the Pacific Ring of Fire.

 

Some important geological structures in the Pacific Ring of Fire zone

• The most important feature of the Pacific Ring of Fire is the San Andreas Fault zone of California which is an active transform fault and offsets a portion of the East Pacific Rise under the south-western United States and Mexico. The motion of the fault generates numerous small earthquakes, multiple times a day, most of which are too small to be felt.

• The Queen Charlotte Fault is an active transform fault that marks the boundary of the North American and Pacific Plates. It is Canada’s right-lateral strike-slip equivalent to the San Andreas Fault to the south in California. It forms an important part of the Pacific Ring of Fire.

• Mount Fuji, Sakurajima, Krakatoa, Merapi, Taal, Mayon and Mauna Loa are some of the important volcanoes which are located on the Pacific Ring of Fire.

This zone is so active because it comprises of the tectonic plates which are moving at the highest velocity.

For example, the Pacific Plate is moving at the rate of 6 cm/year while the Cocos and Nazca plates are moving at the quickest pace at over 10 cm/yr. These rapidly drifting plates cause multiple collision and seduction with other plates in the Pacific Ring of Fire causing multiple volcanic eruption and earthquakes.

Hence, this region hosts the largest number of volcanoes and earthquakes and witnesses some of the most important geophysical phenomenon such as Tsunami.