World Geography Test 3

Answer – c

Answer – b

• The proportion of gases changes in the higher layers of the atmosphere in such a way that oxygen will be almost in negligible quantity at the height of 120 km.
• Similarly, carbon dioxide and water vapour are found only up to 90 km from the surface of the earth

Answer – d

• Waves are actually the energy, not the water as such, which moves across the ocean surface. Water particles only travel in a small circle as a wave passes. Wind provides energy to the waves.
• When a breeze of two knots or less blows over calm water, small ripples form and grow as the wind speed increases until white caps appear in the breaking waves. Waves may travel thousands of km before rolling ashore, breaking and dissolving as surf
• As a wave approaches the beach, it slows down. This is due to the friction occurring between the dynamic water and the sea floor. And, when the depth of water is less than half the wavelength of the wave, the wave breaks. The largest waves are found in the open oceans.

Answer – d

• Steep waves are fairly young ones and are probably formed by local wind. Slow and steady waves originate from far away places, possibly from another hemisphere
• The actual motion of the water beneath the waves is circular. It indicates that things are carried up and forward as the wave approaches, and down and back as it passes.

Answer – b

• The moon’s gravitational pull to a great extent and to a lesser extent the sun’s gravitational pull, are the major causes for the occurrence of tides. Another factor is centrifugal force, which is the force that acts to counter balance the gravity
• The tidal bulges on wide continental shelves, have greater height. When tidal bulges hit the mid-oceanic islands they become low.

Answer – a

• The highest tides in the world occur in the Bay of Fundy in Nova Scotia, Canada. The tidal bulge is 15 – 16 m. Because there are two high tides and two low tides every day (roughly a 24 hour period); then a tide must come in within about a six hour period. As a rough estimate, the tide rises about 240 cm an hour (1,440 cm divided by 6 hours).
• If you have walked down a beach with a steep cliff alongside (which is common there), make sure you watch the tides. If you walk for about an hour and then notice that the tide is coming in, the water will be over your head before you get back to where you started!

GS 1 – Important Geophysical phenomena

• All the above questions belong to this particular section in GS 1, which basically covers most of the Physical geography. Thus direct questions can be asked in Mains from here, hence static knowledge is significant there.

Answer – c

• In winter months, the weather conditions over India are generally influenced by the distribution of pressure in Central and Western Asia.
• A high pressure centre in the region lying to the north of the Himalayas develops during winter attracts winds from the Central Asia.
• Jet stream from the west Asia also influence the winter.

Answer – d

In winter, the surface winds blowing out of the high pressure centre over Central Asia reach India in the form of a dry continental air mass. These continental winds come in contact with tradewinds over northwestern India. The position of this contact zone is not, however, stable.

Occasionally, it may shift its position as far east as the middle Ganga valley with the result that

the whole of the northwestern and northern India up to the middle Ganga valley comes under the influence of dry northwestern winds.

Answer – C

Answer – B

The theory of plate tectonics proposes that the earth’s lithosphere is divided into seven major and some minor plates. Young Fold Mountain ridges, trenches, and/or faults surround these major plates

The major plates are as follows :

(i) Antarctica and the surrounding oceanic plate

(ii) North American (with western Atlantic floor separated from the South American plate along the Caribbean islands) plate

(iii) South American (with western Atlantic floor separated from the North American plate along the Caribbean islands) plate

(iv) Pacific plate

(v) India-Australia-New Zealand plate

(vi) Africa with the eastern Atlantic floor plate

(vii) Eurasia and the adjacent oceanic plate.

Some important minor plates are listed below:

(i) Cocos plate : Between Central America and Pacific plate

(ii) Nazca plate : Between South America and Pacific plate

(iii) Arabian plate : Mostly the Saudi Arabian landmass

(iv) Philippine plate : Between the Asiatic and Pacific plate

(v) Caroline plate : Between the Philippine and Indian plate (North of New Guinea)

(vi) Fuji plate : North-east of Australia.

Other minor plates can be seen in the map given in previous question.

Answer – B

Where new crust is generated as the plates pull away from each other. The sites where the plates move away from each other are called spreading sites. The best-known example of

divergent boundaries is the Mid-Atlantic Ridge. At this, the American Plate(s) is/are separated from the Eurasian and African Plates.

Answer – C

• The thickness of the crust varies under the oceanic and continental areas. Oceanic crust is thinner as compared to the continental crust. The mean thickness of oceanic crust is 5 km whereas that of the continental is around 30 km. The continental crust is thicker in the areas of major mountain systems. It is as much as 70 km thick in the Himalayan region.
• It is made up of heavier rocks having density of 3 g/cm3. This type of rock found in the oceanic crust is basalt. The mean density of material in oceanic crust is 2.7 g/cm3.

Answer – B

• Shield volcanoes are mostly made up of basalt, a type of lava that is very fluid when erupted. For this reason, these volcanoes are not steep.
• They become explosive if somehow water gets into the vent; otherwise, they are characterised by low-explosivity.
• The upcoming lava moves in the form of a fountain and throws out the cone at the top of the vent and develops into cinder cone.

Answer – b

• Calderas are the most explosive of the earth’s volcanoes.
• They are usually so explosive that when they erupt they tend to collapse on themselves rather than building any tall structure. The collapsed depressions are called calderas.
• Their explosiveness indicates that the magma chamber supplying the lava is not only huge but is also in close vicinity.

Answer – C

• Composite Volcanoes are characterised by eruptions of cooler and more viscous lavas than basalt. These volcanoes often result in explosive eruptions.
• Along with lava, large quantities of pyroclastic material and ashes find their way to the ground. This material accumulates in the vicinity of the vent openings leading to formation of layers, and this makes the mounts appear as composite volcanoes.

Answer – A

The Hawaiian volcanoes are the most famous  examples. These volcanoes are mostly made

up of basalt, a type of lava that is very fluid when erupted.

Answer – D

• Mid-Ocean Ridge Volcanoes occur in the oceanic areas. There is a system of mid-ocean ridges more than 70,000 km long that stretches through all the ocean basins.
• The central portion of this ridge experiences frequent eruptions.

Solution: a)

Many tribes live in savanna region. Tribes like the Masai tribes of the East African plateau are pastoralists whereas Hausa of northern Nigeria are settled cultivators.

Solution: c)

Norway has the second longest coastline in the World, and the longest in Europe. Canada has the longest coastline in the world.

Solution: b)

The Arctic Ocean is located within the Arctic Circle and surrounds the North Pole. It

is connected with the Pacific Ocean by a narrow stretch of shallow water known as berring strait.