Daily Quiz #23 UPSC Prelims Marathon – July 26, 2019

Explanation: Metamorphic Rocks:
•Metamorphic rocks are formed through the transformation of pre-existing rocks in a process known as metamorphism. The original rock, or protolith, is subjected to heat and pressure which cause physical, chemical and mineralogical changes to the rock. Protoliths may be igneous, sedimentary or pre-existing metamorphic rocks.
•Metamorphic rocks are formed within the Earth’s crust. Changing temperature and pressure conditions may result in changes to the mineral assemblage of the protolith. Metamorphic rocks are eventually exposed at the surface by uplift and erosion of the overlying rock.
•There are two main types of metamorphism: regional metamorphism and contact, or thermal, metamorphism. Metamorphic rocks are categorised by texture and mineralogy.

Original Rock
Metamorphic Rock
•Limestone
•Sandstone
•Shale
•Coal
•Basalt
•Granite
•Dolomite/Chalk•Marble
•Quartzite
•Slate
•Graphite
•Schist
•Gneiss
•Marble

Explanation: The winds blowing almost in the same direction throughout the year are called prevailing or permanent winds. These are also called as invariable or planetary winds because they involve larger areas of the globe. On the other hand, winds with seasonal changes in their directions are called seasonal winds (e.g., monsoon winds).
On an averages, the location of high and low pressure belts is considered to be stationary on the globe (though they are seldom stationary). Conse¬quently, winds blow from high pressure belts to low pressure belts. The direction of such winds remains more or less the same throughout the year though their areas change seasonally.
Thus, such winds are called permanent winds. Since these winds are distributed all over the globe and these are related to thermally and dynamically induced pressure belts and rotation of the earth and hence they are called planetary winds. These winds include trade winds, westerlies and polar winds (fig. 35.7).

Westerlies:
•The permanent winds blowing from the subtropical high pressure belts (30°-35°) to the subpolar low pressure belts (60°-65°) in both the hemispheres are called westerlies (fig. 35.7).
•The gen¬eral direction of the westerlies is S.W. to N.E. in the northern hemisphere and N.W. to S.E in the southern hemisphere.
•The general characteristic features of the westerlies are largely modified due to cyclones and anticyclones associated with them.
•Because of the dominance of land in the northern hemisphere the westerlies become more com¬plex and complicated and become less effective during summer seasons and more vigorous during winter season.
•These westerlies bring much precipitation in the western parts of the continents (e.g., north-west European coasts) because they pick up much moisture while passing over the vast stretches of the oceans.
•The westerlies become more vigorous in the southern hemi¬sphere because of lack of land and dominance of oceans. Their velocity increases southward and they become stormy.

Explanation:
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.

Explanation: Guru Shikar is located at a height of 1772 meters above sea level. This mountain peak is located at a distance of 15 km from Mount Abu in the Aravalli range. It is the highest peak in the Aravali Range.