The Northern Plains

Correct answer: A. Alluvial deposition by Himalayan rivers

Direct answer: Option A, alluvial deposition by Himalayan rivers. The Northern Plains developed in a large low-lying basin south of the Himalaya. Rivers such as the Indus system, Ganga system, and Brahmaputra carry sediments eroded from mountains and deposit them over very long periods. Repeated deposition builds thick, extensive layers of alluvium, creating flat and fertile plains. Option A is correct because river-borne alluvium is the decisive long-term process. Option B is wrong because lava flows form volcanic igneous surfaces, not the broad alluvial Northern Plains. Option C is wrong because marine coral accumulation is limited to suitable shallow warm seas and is not the main origin of these plains. Option D is wrong because wind-blown desert sand is local and cannot explain the enormous river-built plain. Memory cue: Himalayan rivers bring sediment; sediment builds plains.

Correct answer: B. New alluvium brought by rivers

The direct answer is B: new alluvium brought by rivers. The Northern Plains were built mainly by the deposition of sediments carried by the Indus, Ganga and Brahmaputra river systems and their tributaries. Rivers bring sand, silt and clay from higher areas and spread these materials across the plains, especially during floods. Step by step: weathering produces rock particles; rivers transport them; the flow becomes slower on the plain; sediments are deposited; repeated deposition creates deep, fertile alluvial soil. Option B is correct because fresh alluvium continually adds mineral material and helps maintain fertility. Option A, black lava soil, is mainly associated with basaltic volcanic regions such as parts of the Deccan Plateau, not the main origin of the Northern Plains. Option C, dry sandy soil, generally has low moisture retention and is not the chief reason for fertility. Option D, rocky mountain soil, is not the thick deposited soil of the plains. Fertility may also depend on irrigation and cultivation, but the main geographical factor asked here is river-borne alluvium. Memory cue: Northern Plains = rivers plus alluvium plus fertile fields.

Correct answer: C. Combined deposition of three major river systems

This plain formed through long deposition by three major river systems. Remember the combined river systems for exams.

Correct answer: D. Pebbly porous deposits at the foot of Shiwalik

Bhabar is a belt of coarse pebbles at the foot of Shiwalik. In exams identify it as a porous belt.

Correct answer: A. It is wetter and marshy

In the Bhabar belt, streams disappear into porous deposits of coarse pebbles and boulders. In the Terai belt south of it, this water re-emerges near the surface, making the land very wet and marshy. Option B describes Bhabar, not Terai. Exam tip: remember Bhabar as the belt where water sinks, and Terai as the belt where it reappears.

Correct answer: B. Bhangar

Bhangar is the older alluvial deposit of the Northern Plains. It generally lies on higher terraces above the active floodplains and is not renewed by every annual flood. Because it is older, it may contain calcareous nodules called kankar. Khadar is different: it is newer alluvium found in lower floodplain areas and is more regularly renewed by river deposits.

The question gives two identifying clues: older alluvium and a higher part of the plains. Both point to Bhangar, so option B is correct. Khadar would be correct only for newer alluvium or active floodplain deposits. Terai is a wet marshy belt near the Himalayan foothills, while Bhabar is a porous belt where streams may disappear; neither term means higher older alluvium.

Correct answer: C. Khadar

Direct answer: Option C, Khadar. The Northern Plains have different alluvial surfaces. Khadar is the newer alluvium deposited by rivers, especially on the lower floodplain, and floods can add fresh layers of silt each year. Because the material is renewed, Khadar is generally more fertile. Option A, doab, means the land lying between two rivers; it is a location term, not specifically the name for new floodplain alluvium. Option B, Bhabar, is the pebbly belt along the Himalayan foothills where streams often disappear into porous deposits. Option D, Bhangar, is older alluvium, usually lying above the active floodplain and containing older deposits. Therefore the age and flood position are the deciding clues: new and regularly renewed = Khadar; old and higher = Bhangar. Memory cue: Khadar is “new,” while Bhangar is “old.”

Correct answer: A. Alluvial deposits

The Ganga plain has been formed mainly by alluvium deposited by the Ganga and its tributaries. This material includes sand, silt and clay carried from the Himalayas and other regions, making it a vast river-built plain. Glacial deposits are associated mainly with glacier-dominated areas, not with the main formation of the Ganga plain. Exam tip: Sediments carried and deposited by rivers are called alluvium.

Correct answer: B. Khadar floodplain

Khadar is the newer alluvial part of the Northern Plains. During repeated floods, rivers deposit fresh, fine and fertile silt in this area, so the Khadar floodplain is renewed regularly. The Shiwalik Hills are Himalayan foothills, not flood-deposited plains. Exam tip: associate fresh alluvium and flood renewal with Khadar.

Correct answer: C. Because water seeps through pebbly porous deposits

The direct answer is C, water seeping through pebbly porous deposits. Bhabar is a narrow belt along the foothills of the Himalayas. Rivers coming down from the mountains deposit large pebbles, stones, and coarse sediments there. Step by step: the streams reach the coarse deposit; the spaces between pebbles are large and connected; water enters these spaces and moves downward; therefore, many small streams disappear from the visible surface. Option C is correct because the deposits are highly porous and permeable. Option A is wrong because heavy snowfall may feed rivers but does not explain their disappearance into Bhabar deposits. Option B is wrong because Bhabar is inland and sea waves do not cause this process. Option D is wrong because melting lava is unrelated to the alluvial, pebble-rich formation of Bhabar. A key exam cue is: Bhabar means coarse, porous deposits where streams sink; Terai farther south is wetter and often brings water back near the surface.

Correct answer: D. High moisture, surface water and waterlogging

The Terai is a marshy, highly moist belt south of the Bhabar region. Streams that disappear into the porous Bhabar re-emerge here, producing surface water, waterlogging and marshes. These conditions support dense natural vegetation and provide suitable habitats for wildlife. Highly saline soil, by contrast, is generally unfavourable for forest growth. Exam tip: Link the Terai with re-emerging water, marshy land and dense forests.

Correct answer: A. Long river deposition and leveling

The direct answer is A: long-term river deposition and leveling. The Northern Plains are broad depositional plains formed from sediments carried by large river systems. When rivers leave the mountains and enter areas with a lower gradient, their speed decreases and they deposit sand, silt and clay. Repeated deposition over a long time fills low areas and produces a wide, relatively level surface. Option A is correct because it includes both the main process, deposition, and its long-term leveling effect. Option B is wrong because intense volcanic eruptions would create volcanic landforms and lava deposits, not the alluvial plain described here. Option C is wrong because permanent sea-water accumulation would produce a marine environment, not the inland river plain of northern India. Option D is wrong because the Himalayas have certainly been eroded, but “complete erosion” is false and is not the immediate process forming the level plain. The exact chain is mountain erosion, river transport, reduced slope, sediment deposition, repeated filling of depressions, and a level plain. Memory cue: a flat alluvial plain is built by rivers laying down sediments for a long time.

Correct answer: B. It indicates calcium carbonate deposits in older alluvium

Bhangar is the older alluvium of the Northern Plains and generally lies above the active floodplain. It contains kankar, which are hard deposits or nodules of calcium carbonate. Thus, kankar is an important indicator of Bhangar’s older alluvial nature. New alluvium is associated with Khadar, so option C is incorrect. Exam tip: Remember—Bhangar: old alluvium and kankar; Khadar: new and more fertile alluvium.

Correct answer: C. Because of soft alluvium and low slope

Rivers shift easily on low slopes and soft alluvium. Treat it as a feature of plain rivers in exams.

Correct answer: D. Braided flow and deposition

The Brahmaputra flows through a broad plain and carries a large quantity of sand, silt, and other sediments. Its channel often divides into several smaller channels and later joins again. Such a river pattern is called a braided channel. When the river’s speed decreases or its flow changes, the sediments are deposited between the channels. These deposited materials can gradually rise above the water and form temporary or permanent river islands.

Therefore, choice D is correct: braided flow and deposition. Desert winds, cooling lava, and sea-wave erosion do not explain the formation of islands in the Brahmaputra plain. The important sequence is that the river carries sediment, divides into several channels, deposits material, and leaves sedimentary bars or islands between the channels. This is why the Brahmaputra is especially known for river islands in its plain.

Correct answer: A. It is the final low depositional part of river deposition

A delta forms from final deposits carried by rivers. Link deltas with river deposition in exams.

Correct answer: B. Fertile alluvial soil and sufficient water

Alluvial soil and river water support agriculture. Mention both soil and water for agriculture in exams.

Correct answer: A. Very gentle slope in the plains

River speed depends greatly on the gradient, or slope, of the land. In the Northern Plains, the land is broad and almost level, so the river channel has only a gentle fall. Water therefore loses the strong downward pull that it has on a steep mountain slope, and the current becomes slower. This physical feature is the main reason for the slow flow mentioned in the question.

A river may still carry a large volume of water in the plains, but a large discharge does not automatically mean a very fast current. The low gradient reduces the component of gravity acting along the channel and encourages deposition of alluvium in suitable places. Thus option A, very gentle slope in the plains, is correct. Lack of water is not the general reason, and sea depth or the closeness of mountains does not explain the river's normal inland speed.

Correct answer: B. Due to low gradient and lateral erosion

The direct answer is B: low gradient and lateral erosion. A river flowing through mountains usually has a steep slope, strong downward cutting and a relatively narrow channel. In the Northern Plains the slope is gentle, so the river loses speed and has more opportunity to erode its banks sideways. The outer bank of a bend is eroded while sediment is deposited on the inner bank. Repeated unequal erosion and deposition make the channel curve into meanders. Option A is wrong because a hard mountain slope generally encourages vertical erosion and straighter, confined channels, not common wide meanders. Option B is correct because low slope plus lateral bank erosion produces bends. Option C is wrong because volcanic ash is not the controlling reason for ordinary river meanders. Option D is wrong because glaciers move as ice and do not explain the bends of alluvial plain rivers. The reasoning is low gradient, slower flow, side cutting, deposition, and increasing bends. Memory cue: steep mountains cut down; gentle plains cut sideways and meander.

Correct answer: A. The land lying between two rivers of the Indus river system

A doab is the fertile tract of land lying between two rivers. The Punjab Plain has many such tracts between rivers of the Indus system and their tributaries, so doabs are prominent there. Waves of the Bay of Bengal are associated with coastal areas, not the Punjab Plain. Exam tip: Remember doab as land between ‘two waters’ or two rivers.

Correct answer: A. General eastward increase in rainfall

Higher rainfall in the east increases humidity. Remember regional contrasts within the Ganga plain.

Correct answer: B. Level land fertile soil and water availability

Level land and fertile alluvium support living and farming. Mention land soil and water for settlement in exams.

Correct answer: B. Bhabar at the foot of Shiwalik and Terai south of it

Bhabar occurs near Shiwalik and Terai lies south of it. Remember the north to south sequence for exams.

Correct answer: C. Heavy rainfall and high sediment load

Heavy rainfall and sediment affect the river bed and increase floods. Treat Brahmaputra as flood prone in exams.

Correct answer: A. Khadar

Direct answer: Option A, Khadar. The Northern Plains contain different alluvial surfaces. Khadar is the newer alluvium deposited in the active floodplain. When a river overflows, it spreads fine silt and other fresh sediment across nearby land. If this happens repeatedly, a new layer is added after many floods, making the soil comparatively young and often fertile. Option A is correct because repeated fresh deposition is the defining clue for Khadar. Option B is wrong because Bhangar is older alluvium, generally above the active floodplain, and is not renewed by every flood. Option C is wrong because Bhabar is a narrow coarse-pebble belt near the Himalayan foothills where streams often disappear underground. Option D is wrong because a plateau is an elevated relatively flat landform, not a flood-deposited alluvial category. Memory cue: new alluvium means Khadar; old alluvium means Bhangar.