Daily Quiz: UPSC Prelims Marathon – February 28, 2020

India is a vast country. Lying entirely in the Northern hemisphere the main land extends between latitudes 8°4’N and 37°6’N and longitudes 68°7’E and 97°25’E. The Tropic of Cancer (23° 30’N) divides the country into almost two equal parts. To the southeast and southwest of the mainland, lie the Andaman and Nicobar Islands and the Lakshadweep islands in Bay of Bengal and Arabian Sea respectively. The land mass of India has an area of 3.28 million square km. India’s total area accounts for about 2.4 per cent of the total geographical area of the world. It is clear that India is the seventh largest country of the world. India has a land boundary of about 15,200 km and the total length of the coast line of the mainland including Andaman and Nicobar and Lakshadweep is 7,516.6 km.

The Peninsular plateau is a tableland composed of the old crystalline, igneous and metamorphic rocks. It was formed due to the breaking and drifting of the Gondwana land and thus, making it a part of the oldest landmass. The Deccan Plateau is a triangular landmass that lies to the south of the river Narmada. The Satpura range flanks its broad base in the north while the Mahadev, the Kaimur hills and the Maikal range from its eastern extensions. Locate these hills and ranges in the physical map of India. The Deccan Plateau is higher in the west and slopes gently eastwards. An extension of the Plateau is also visible in the northeast– locally known as the Meghalaya, Karbi-Anglong Plateau and North Cachar Hills. It is separated by a fault from the Chotanagpur Plateau. Three Prominent hill ranges from the west to east are the Garo, the Khasi and the Jaintia Hills.

The Western Ghats are higher than the Eastern Ghats. Their average elevation is 900– 1600 metres as against 600 metres of the Eastern Ghats. The Eastern Ghats stretch from the Mahanadi Valley to the Nigiris in the south. The Eastern Ghats are discontinuous and irregular and dissected by rivers draining into the Bay of Bengal. The Western Ghats cause orographic rain by facing the rain bearing moist winds to rise along the western slopes of the Ghats. The Western Ghats are known by different local names. The height of the Western Ghats progressively increases from north to south. The highest peaks include the Anai Mudi (2,695metres) and the Doda Betta (2,637 metres). Mahendragiri (1,501 metres) is the highest peak in the Eastern Ghats. Shevroy Hills and the Javadi Hills are located to the southeast of the Eastern Ghats. Locate the famous hill stations of Udagamandalam, popularly known as Ooty and the Kodaikanal.

The Indian desest lies towards the western margins of the Aravali Hills. It is an undulating sandy plain covered with sand dunes. This region receives very low rainfall below 150 mm per year. It has arid climate with low vegetation cover. Streams appear during the rainy season. Soon after they disappear into the sand as they do not have enough water to reach the sea. Luni is the only large river in this region.

Earthquakes produce three types of seismic waves: primary waves, secondary waves, and surface waves. Each type moves through materials differently. In addition, the waves can reflect, or bounce, off boundaries between different layers. The waves can also bend as they pass from one layer into another. Scientists learn about Earth’s layers by studying the paths and speeds of seismic waves traveling through Earth.

• Primary Waves: The fastest seismic waves are called primary waves, or P waves. These waves are the first to reach any particular location after an earthquake occurs.
• Secondary Waves: Secondary waves are the second seismic waves to arrive at any particular location after an earthquake, though they start at the same time as primary waves. Secondary waves travel through Earth’s interior at about half the speed of primary waves. Secondary waves are also called S waves. As they pass through a material, the material’s particles are shaken up and down or from side to side. Secondary waves rock small buildings back and forth as they pass.
• Surface Waves: Surface waves are seismic waves that move along Earth’s surface, not through its interior. They make the ground roll up and down or shake from side to side. Surface waves cause the largest ground movements and the most damage. Surface waves travel more slowly than the other types of seismic waves.