Daily Quiz: UPSC Prelims Marathon (Geography & Environment)–October 16th,2020

Sedimentary rocks are formed by the accumulation of sediments. There are three basic types of sedimentary rocks.
•Clastic sedimentary rocks such as breccia, conglomerate, sandstone, siltstone, and shale are formed from mechanical weathering debris.
•Chemical sedimentary rocks, such as rock salt, iron ore, chert, flint, some dolomites, and some limestone, form when dissolved materials precipitate from solution.
•Organic sedimentary rocks such as coal, some dolomites, and some limestone, form from the accumulation of plant or animal debris.
Source: NCERT

Fold Mountains are created through a process called orogeny. An orogenic event takes millions of years to create a fold mountain.
•When a tectonic plate gets pressure from two sides, it gets folded. Some of its portion becomes elevated and forms the mountains.
•The depressions form the valleys. The Himalayas, the Rockies, the Andes and the Alps are examples of Fold Mountain.
•They are the young mountains of the world and hence they have some of the highest peaks of the world.
Source: NCERT

A caldera is a large depression formed when a volcano erupts and collapses.
•During a volcanic eruption, magma present in the magma chamber underneath the volcano is expelled, often forcefully.
•When the magma chamber empties, the support that the magma had provided inside the chamber disappears.
•As a result, the sides and top of the volcano collapse inward. Calderas vary in size from one to 100 kilometers (0.62 to 62 miles) in diameter.
•Some calderas form a lake as the bowl-shaped depression fills with water. A famous example is Crater Lake, in Oregon.
•This caldera formed about 7,000 years ago when a stratovolcano, Mt. Mazama, violently erupted.
•For several thousand years after this eruption, smaller volcanic eruptions continued inside the caldera.
•One of these eruptions was so large it formed an island in Crater Lake named Wizard Island.
Source: National Geographic Channel

The Great Lakes are, from west to east: Superior, Michigan, Huron, Erie and Ontario.
•They are a dominant part of the physical and cultural heritage of North America.
•Shared with Canada and spanning more than 750 miles (1,200 kilometers) from west to east, these vast inland freshwater seas provide water for consumption, transportation, power, recreation and a host of other uses.
Source: Majid Hussain

All waters in nature, whether rain water or ocean water, contain dissolved mineral salts. Salinity is the term used to define the total content of dissolved salts in sea water. Factors affecting ocean salinity are mentioned below:
•The salinity of water in the surface layer of oceans depends mainly on evaporation and precipitation.
•Surface salinity is greatly influenced in coastal regions by the fresh water flow from rivers, and in Polar Regions by the processes of freezing and thawing of ice.
•Wind, also influences salinity of an area by transferring water to other areas.
•The ocean currents contribute to the salinity variations. Salinity, temperature and density of water are interrelated. Hence, any change in the temperature or density influences the salinity of water in an area.
Source: NCERT

About 71 per cent of the planetary water is found in the oceans. The remaining is held as freshwater in glaciers and icecaps, groundwater sources, lakes, soil moisture, atmosphere, streams and within life.

Source: NCERT

Storm Surge.
•Storm surge is the abnormal rise in seawater level during a storm, measured as the height of the water above the normal predicted astronomical tide.
•The surge is caused primarily by a storm’s winds pushing water onshore.
•The amplitude of the storm surge at any given location depends on the orientation of the coast line with the storm track;
•The intensity, size, and speed of the storm; and the local bathymetry.
Source: NOAA

Oceanic and atmospheric Rossby waves — also known as planetary waves — naturally occur largely due to the Earth’s rotation. These waves affect the planet’s weather and climate.
•Waves in the ocean come in many different shapes and sizes.
•Slow-moving oceanic Rossby waves are fundamentally different from ocean surface waves.
•Unlike waves that break along the shore, Rossby waves are huge, undulating movements of the ocean that stretch horizontally across the planet for hundreds of kilometers in a westward direction.
•They are so large and massive that they can change Earth’s climate conditions.
Along with rising sea levels, King Tides, and the effects of El Niño, oceanic Rossby waves contribute to high tides and coastal flooding in some regions of the world.
Source: NOAA

Primitive subsistence agriculture or shifting cultivation is widely practised by many tribes in the tropics, especially in Africa, south and Central America and south East Asia.
The vegetation is usually cleared by fire, and the ashes add to the fertility of the soil. Shifting cultivation is thus, also called slash and burn agriculture.
It is prevalent in tropical region in different names, e.g. Jhuming in North eastern states of India, Milpa in Central America and Mexico and Ladang in Indonesia and Malaysia.
Source: NCERT

Collective farming.
•The basic principle behind collective farming is based on social ownership of the means of production and collective labour.
•Collective farming or the model of Kolkhoz was introduced in erstwhile Soviet Union to improve upon the inefficiency of the previous methods of agriculture and to boost agricultural production for self-sufficiency.
•The farmers used to pool in all their resources like land, livestock and labour.
Source: NCERT