Day-567 | Daily MCQs | UPSC Prelims | GEOGRAPHY

Answer: B
Context:
• Statement 1 is correct: P- Waves can pass through air, solid and liquid while S-waves can pass through the solids only.
• Statement 2 is incorrect: P-waves are 1.7 times faster than S-waves.
• Statement 3 is correct: Rayleigh waves cause the maximum damage from an earthquake.
Additional Information
Earthquake Waves-
• Two main terms: Focus and Epicentre
• The rock rupture or sudden breakage of rocks deep within the crust at a point or place is known as focus or hypocenter, and the point on the Earth’s surface located vertically above the focus is termed as epicentre.
• The depth of focus from the epicentre, called as focal depth, is an important parameter in determining the potential damage of an Earthquake.
• The vibrations or seismic waves radiate from this point of rupture or focus, and are propagated up to the Earth’s surface.
There are two types of waves: Body waves and Surface waves released during an Earthquake.
Primary Waves:
• P wave is the fastest kind of seismic wave and first to arrive at a seismic station that can be recorded on the Seismograph.
• This can move through solid rock, liquids and gases.
• P waves are “push and pull” waves like sound waves, which pushes and pulls the air in each particle vibrating to and fro in the direction of propagation.
• These are also known as compressional or longitudinal waves.
• P-wave velocity in earthquakes is in the range 5 to 8 km/s.
• The precise speed varies according to the region of the Earth’s interior, from less than 6 km/s in the Earth’s crust to 13.5 km/s in the lower mantle, and 11 km/s through the inner core.
• P-waves are about 1.7 times faster than the S-waves.
Secondary Waves:
• The second type of body waves is the S wave or secondary wave which appears only after the P waves have arrived.
• These are transverse or shear waves, in which the motion of each particle is at right angle to the direction of propagation.
• S waves can pass only through solid rock and move rock particles up and down, or side-to-side-perpendicular to the direction of the wave travels.
• Both P and S waves travel through the body of the Earth hence, they are called as body waves.
• S-waves cannot pass through fluids (liquids and gases) as fluids do not support shear stresses.
Surface waves are two types: Love waves and Rayleigh waves.
Love wave:
It is the fastest surface wave and moves the ground from side-to-side in horizontal motion.
Rayleigh waves:
• They are much larger than the other waves move the ground up and down and side-to-side in the same direction of wave.
• It rolls along the ground just like a wave rolls across the ocean or lake.
• Most of the shaking and damage from an earthquake is due to the Rayleigh wave.

Answer: B
Explanation:
• Statement 1 is correct: In the desert, oases are the natural depressions of varying sizes. In these depressions, the underground water reaches the surface. So, statement 2 is incorrect.
• They are typically supplied by groundwater or springs and temporary rivers can also sustain some oases to desert depressions.
• Statement 3 is correct: Oases act as natural spring in the hostile desert and thus support a settled life. The oasis people live in mud-brick houses with flat roofs, closely packed together. A planned settlement with a suq (central market place), the mosque, school and shopping blocks. eg. Tafilalet Oasis in Morocco.

Answer: D
Explanation:
Pair 1 is matched incorrectly:
Rafah crossing:
• Rafah crossing is in news due to ongoing Israel-Hamas conflict.
• In the wake of Israel’s blockade of the Gaza Strip following the October 7 attack by Hamas, the Rafah border crossing with Egypt has become a crucial point for civilians seeking to enter or leave Gaza.
• This crossing, unlike others, is not controlled by Israel.
Pair 2 is matched incorrectly:
Zangezur corridor: In news due to ongoing Armenia-Azerbaijan conflict.
• Zangezur, which is currently part of southern Armenia, has been a disputed territory since World War I.
• Under the communist Soviet Union, the area, which is located between Baku’s Nakhchivan autonomous region and Azerbaijan, became part of the Armenian Soviet Socialist Republic (SSR). Today, Armenia considers the area its Syunik province.
• The Zangezur Corridor runs through Azerbaijan and Armenia territories reaching Nakhchivan, Azerbaijan’s autonomous region, which neighbours Türkiye.
• The corridor is part of a strategic transportation route extending from the Azerbaijani capital, Baku, to Kars, Türkiye’s eastern province, passing through Armenian territory near the country’s border with Iran.
Pair 3 is matched incorrectly:
• Darien gap is a geographic region in the Isthmus of Panama connecting the American continents within Central America.
• It is consisting of a large watershed, forest, and mountains in Panama’s Darién Province and the northern portion of Colombia’s Chocó Department.

Answer: A
Explanation:
Statement 1 is correct:
• The Ram Temple in Ayodhya is a much-awaited landmark in Hindu religion, with the idol of Lord Ram and Sita to be carved out of a special stone known as the Shaligram Stone.
• Anthropologist Holly Walters In her book, ‘Shaligram Pilgrimage in the Nepal Himalayas’,has written that shaligram stones are fossils of ammonite, which is a type of mollusc that lived between 400 million and 65 million years ago.
• Referring to a Geological Survey of India publication from 1904, Walters wrote that shaligram stones “date specifically from the Early Oxfordian to the Late Tithonian Age near the end of the Jurassic Period some 165-140 million years ago”.
Statement 2 is incorrect:
• These stones are mostly found in riverbeds or banks of the Kali Gandaki, a tributary of the Gandaki River in Nepal.
• These stones are revered by Hindus who believe it to be a representation of Lord Vishnu.
• According to Hindu mythology, Lord Vishnu was cursed to become the shaligram stone for “betraying the chastity of the goddess Tulsi”.

Answer: B
Explanation:
Statement 1 is incorrect:
Theri Desert:
• It is a small desert situated in the state of Tamil Nadu.
• It consists of red sand dunes and is confined to the Thoothukudi district.
• The red dunes are called theri in Tamil.
• They consist of sediments dating back to the Quaternary Period (which began 2.6 million years ago) and are made of marine deposits.
• They have very low water and nutrient retention capacity.
• The dunes are susceptible to aerodynamic lift. This is the push that lets something move up. It is the force that is the opposite of weight.
Statement 2 is correct:
Formation of Theri desert:
• Theory 1: Theri appear as gentle, undulating terrain. The lithology (the study of general physical characteristics of rocks) of the area shows that the area might have been a paleo (ancient) coast in the past. The presence of limestone in many places indicates marine transgression.
• Theory 2: The present-day theris might have been formed by the confinement of beach sand locally, after regression of the sea. When high velocity winds from the Western Ghats blew east, they induced migration of sand grains and accumulation of dunes.
• Theory 3: Another view is that these are geological formations that appeared in a period of a few hundred years.
• There is a lot of red sand spread over these theris.
• The red sand is brought from the surface of a broad belt of red loam in the plains of the Nanguneri region (about 57 kilometres from this area in Tirunelveli district) by south west monsoon winds during May-September.
Additional Information
Mineral Composition of Theri:
• The petrographical study (petrography is the study of composition and properties of rocks) and X-ray diffraction analysis (a method used to determine a material’s crystallographic structure) of the red sand dunes reveal the presence of heavy and light minerals.
• These include Ilmenite, Magnetite, Rutile, Garnet, Zircon, Diopside, Tourmaline, Hematite, Goethite, Kyanite, Quartz, Feldspar, and Biotite.
• The iron-rich heavy minerals like ilmenite, magnetite, garnet, hypersthene, and rutile present in the soil had undergone leaching by surface water and were then oxidized because of the favorable semi- arid climatic conditions.
• It was due to these processes that the dunes near Tiruchendur, a coastal town of the Thoothukudi district are red-colored.