Class 11 Geography: Landforms and Their Evolution — Chapter Question Set

(a) Youth stage — This is the textbook-supported choice for the question.

(d) Canyon — This is the textbook-supported choice for the question.

(a) Humid region — This is the textbook-supported choice for the question.

(d) An irregular surface with sharp pinnacles, grooves and ridges — This is the textbook-supported choice for the question.

(b) Glacial valley — This is the textbook-supported choice for the question.

d) glaciers, waves perform erosion — The textbook states: LANDFORMS AND THEIR EVOLUTION A fter weathering processes have had their actions on the earth materials making up the surface of the earth, the geomorphic agents like running water, ground water, wind, glaciers, waves perform erosion.

c) already known to you that erosion causes chan — The textbook states: It is already known to you that erosion causes changes on the surface of the earth.

b) surface of the earth — The textbook states: Deposition follows erosion and because of deposition too, changes occur on the surface of the earth.

a) a landform? — The textbook states: As this chapter deals with landforms and their evolution ‘first’ start with the question, what is a landform?

d) called landforms — The textbook states: In simple words, small to medium tracts or parcels of the earth’s surface are called landforms.

c) a small to medium sized part of the surface o — The textbook states: If landform is a small to medium sized part of the surface of the earth, what is a landscape?

b) tracts of earth’s surface) — The textbook states: Several related landforms together make up landscapes, (large tracts of earth’s surface).

a) a result of the action of certain geomorphic — The textbook states: Each landform has its own physical shape, size, materials and is a result of the action of certain geomorphic processes and agent(s).

d) time to take shape — The textbook states: Actions of most of the geomorphic processes and agents ar e slow, and hence the r esults take a long time to take shape.

c) geomorphic processes and agents — The textbook states: Landforms once formed may change in their shape, size and nature slowly or fast due to continued action of geomorphic processes and agents.

b) modifications in the landforms — The textbook states: Due to changes in climatic conditions and vertical or horizontal movements of landmasses, either the intensity of processes or the processes themselves might change leading to new modifications in the landforms.

a) once formed — The textbook states: Evolution here implies stages of transformation of either a part of the earth’s surface from one landform into another or transformation of individual landforms after they are once formed.

d) and changes through time — The textbook states: That means, each and every landform has a history of development and changes through time.

c) mature and old age — The textbook states: A landmass passes through stages of development somewhat comparable to the stages of life — youth, mature and old age.

b) considered the most important of the geomorph — The textbook states: RUNNING WATER In humid regions, which receive heavy rainfall running water is considered the most important of the geomorphic agents in bringing about the degradation of the land surface.

a) associated with vigorous and youthful rivers — The textbook states: Most of the erosional landforms made by running water are associated with vigorous and youthful rivers flowing over steep gradients.

d) velocity, facilitating active deposition — The textbook states: With time, stream channels over steep gradients turn gentler due to continued erosion, and as a consequence, lose their velocity, facilitating active deposition.

c) flowing over steep slopes — The textbook states: Ther e may be depositional forms associated with streams flowing over steep slopes.

b) medium to gentle slopes — The textbook states: But these phenomena will be on a small scale compared to those associated with rivers flowing over medium to gentle slopes.

a) the deposition — The textbook states: The gentler the river channels in gradient or slope, the greater is the deposition.

d) CHAPTER — The textbook states: When the stream beds turn gentler due to continued erosion, downward CHAPTER cutting becomes less dominant and lateral erosion of banks increases and as a consequence the hills and valleys are reduced to plains.

c) high land mass possible? — The textbook states: Is complete reduction of relief of a high land mass possible?

b) narrow to wide paths — The textbook states: Depending upon irregularities of the land surface, the overland flow may concentrate into narrow to wide paths.

a) removed in the direction of flow and graduall — The textbook states: Because of the sheer friction of the column of flowing water, minor or major quantities of materials from the surface of the land are removed in the direction of flow and gradually small and narrow rills will form.

d) a network of valleys — The textbook states: These rills will gradually develop into long and wide gullies; the gullies will further deepen, widen, lengthen and unite to give rise to a network of valleys.

c) cascades will be removed — The textbook states: In the early stages, down-cutting dominates during which irregularities such as waterfalls and cascades will be removed.

b) valley sides becomes severe — The textbook states: In the middle stages, streams cut their beds slower , and lateral er osion of valley sides becomes severe.

a) reduced to lower and lower slopes — The textbook states: Gradually, the valley sides are reduced to lower and lower slopes.

d) likewise lowered until they are almost comple — The textbook states: The divides between drainage basins are likewise lowered until they are almost completely flattened leaving finally, a lowland of faint relief with some low resistant remnants called monadnocks standing out here and there.

c) called a peneplain (an almost plain) — The textbook states: This type of plain forming as a result of stream erosion is called a peneplain (an almost plain).

b) Youth Streams — The textbook states: The characteristics of each of the stages of landscapes developing in running water regimes may be summarised as follows: Youth Streams are few during this stage with poor integration and flow over original slopes showing shallow V-shaped valleys with no floodplains or with very narrow floodplains along trunk streams.

a) broad and flat with marshes — The textbook states: Streams divides are broad and flat with marshes, swamp and lakes.

d) these broad upland surfaces — The textbook states: Meanders if present develop over these broad upland surfaces.

c) themselves into the uplands — The textbook states: These meanders may eventually entrench themselves into the uplands.

b) exposed — The textbook states: Waterfalls and rapids may exist wher e local hard rock bodies are exposed.

a) plenty with good integration — The textbook states: Mature During this stage streams are plenty with good integration.

d) still V-shaped but deep — The textbook states: The valleys are still V-shaped but deep; trunk streams are broad enough to have wider floodplains within which streams may flow in meanders confined within the valley.

c) stream divides turn sharp — The textbook states: The flat and broad inter stream areas and swamps and marshes of youth disappear and the stream divides turn sharp.

b) few with gentle gradients — The textbook states: Old Smaller tributaries during old age are few with gentle gradients.

a) levees, oxbow lakes, etc — The textbook states: Streams meander freely over vast floodplains showing natural levees, oxbow lakes, etc.

d) broad and flat with lakes — The textbook states: Divides are broad and flat with lakes, swamps and marshes.

c) at or slightly above sea level — The textbook states: Most of the landscape is at or slightly above sea level.

b) give rise to valleys — The textbook states: EROSIONAL LANDFORMS Valleys Valleys start as small and narrow rills; the rills will gradually develop into long and wide gullies; the gullies will further deepen, widen and lengthen to give rise to valleys.

a) gorge, canyon , etc — The textbook states: Depending upon dimensions and shape, many types of valleys like V-shaped valley, gorge, canyon , etc.

d) wider at its top than at its bottom — The textbook states: In contrast, a canyon is wider at its top than at its bottom.

Incised or Entrenched Meanders In streams that flow rapidly over steep gradients, normally erosion is concentrated on the bottom of the stream channel. But very deep and wide meanders can also be found cut in hard rocks. Meanders In large flood and delta plains, rivers rarely flow in straight courses.

LANDFORMS AND THEIR EVOLUTION A fter weathering processes have had their actions on the earth materials making up the surface of the earth, the geomorphic agents like running water, ground water, wind, glaciers, waves perform erosion. When sink holes and dolines join together because of slumping of materials along their margins or due to roof collapse of caves, long, narrow to wide trenches called valley sinks or Uvalas form. Assuming sea level to be constant, two types of coasts are considered to explain the concept of evolution of coastal landforms: (i) high, rocky coasts (submer ged coasts); (ii) low, smooth and gently sloping sedimentary coasts (emerged coasts).

Because of the sheer friction of the column of flowing water, minor or major quantities of materials from the surface of the land are removed in the direction of flow and gradually small and narrow rills will form. The characteristics of each of the stages of landscapes developing in running water regimes may be summarised as follows: Youth Streams are few during this stage with poor integration and flow over original slopes showing shallow V-shaped valleys with no floodplains or with very narrow floodplains along trunk streams. Sinkholes are very common in limestone/ karst areas.

Another is linear flow as streams and rivers in valleys. Depositional Landforms Many depositional forms develop within the limestone caves. The faces of divides or spurs of such hanging valleys opening into main glacial valleys are quite often truncated to give them an appearance like triangular facets.

The wind action creates a number of interesting erosional and depositional features in the deserts. That means, the weathered debris in deserts is moved by not only wind but also by rain/sheet wash. List the erosional features carved out by wind action and action of sheet floods.

LANDFORMS AND THEIR EVOLUTION A fter weathering processes have had their actions on the earth materials making up the surface of the earth, the geomorphic agents like running water, ground water, wind, glaciers, waves perform erosion.

It is already known to you that erosion causes changes on the surface of the earth.

Deposition follows erosion and because of deposition too, changes occur on the surface of the earth.

As this chapter deals with landforms and their evolution ‘first’ start with the question, what is a landform?

In simple words, small to medium tracts or parcels of the earth’s surface are called landforms.

If landform is a small to medium sized part of the surface of the earth, what is a landscape?

Several related landforms together make up landscapes, (large tracts of earth’s surface).

Each landform has its own physical shape, size, materials and is a result of the action of certain geomorphic processes and agent(s).

Actions of most of the geomorphic processes and agents ar e slow, and hence the r esults take a long time to take shape.

Landforms once formed may change in their shape, size and nature slowly or fast due to continued action of geomorphic processes and agents.

Due to changes in climatic conditions and vertical or horizontal movements of landmasses, either the intensity of processes or the processes themselves might change leading to new modifications in the landforms.

Evolution here implies stages of transformation of either a part of the earth’s surface from one landform into another or transformation of individual landforms after they are once formed.

That means, each and every landform has a history of development and changes through time.

A landmass passes through stages of development somewhat comparable to the stages of life — youth, mature and old age.

What are the two important aspects of the evolution of landforms?

RUNNING WATER In humid regions, which receive heavy rainfall running water is considered the most important of the geomorphic agents in bringing about the degradation of the land surface.

One is overland flow on general land surface as a sheet.

Another is linear flow as streams and rivers in valleys.

Most of the erosional landforms made by running water are associated with vigorous and youthful rivers flowing over steep gradients.

With time, stream channels over steep gradients turn gentler due to continued erosion, and as a consequence, lose their velocity, facilitating active deposition.

LANDFORMS AND THEIR EVOLUTION A fter weathering processes have had their actions on the earth materials making up the surface of the earth, the geomorphic agents like running water, ground water, wind, glaciers, waves perform erosion. It is already known to you that erosion causes changes on the surface of the earth. Deposition follows erosion and because of deposition too, changes occur on the surface of the earth. RUNNING WATER In humid regions, which receive heavy rainfall running water is considered the most important of the geomorphic agents in bringing about the degradation of the land surface. Most of the erosional landforms made by running water are associated with vigorous and youthful rivers flowing over steep gradients. Alluvial fans in humid areas show normally low cones with gentle slope from head to toe and they appear as high cones with steep slope in arid and semi-arid climates. But in rocks like limestones or dolomites rich in calcium carbonate, the surface water as well as groundwater through the chemical process of solution and precipitation deposition develop varieties of landforms.

RUNNING WATER In humid regions, which receive heavy rainfall running water is considered the most important of the geomorphic agents in bringing about the degradation of the land surface. Alluvial fans in humid areas show normally low cones with gentle slope from head to toe and they appear as high cones with steep slope in arid and semi-arid climates. But in rocks like limestones or dolomites rich in calcium carbonate, the surface water as well as groundwater through the chemical process of solution and precipitation deposition develop varieties of landforms. EROSIONAL LANDFORMS Pools, Sinkholes, Lapies and Limestone Pavements Small to medium sized round to sub-rounded shallow depressions called swallow holes form on the surface of limestones through solution. Sinkholes are very common in limestone/ karst areas. Caves In areas where there are alternating beds of rocks (shales, sandstones, quartzites) with limestones or dolomites in between or in areas where limestones are dense, massive and occurring as thick beds, cave formation is prominent. EROSIONAL LANDFORMS Cliffs, Terraces, Caves and Stacks Wave-cut clif fs and terraces ar e two for ms usually found where erosion is the dominant shore process.

When the stream beds turn gentler due to continued erosion, downward CHAPTER cutting becomes less dominant and lateral erosion of banks increases and as a consequence the hills and valleys are reduced to plains. This load becomes too heavy for the streams to be carried over gentler gradients and gets dumped and spread as a broad low to high cone shaped Deltas Deltas are like alluvial fans but develop at a different location. Alluvial fans in humid areas show normally low cones with gentle slope from head to toe and they appear as high cones with steep slope in arid and semi-arid climates. Glaciers can cause significant damage to even un-weathered rocks and can reduce high mountains into low hills and plains. As glaciers continue to move, debris gets removed, divides get lowered and eventually the slope is reduced to such an extent that glaciers will stop moving leaving only a mass of low hills and vast outwash plains along with other depositional features. If three or more radiating glaciers cut headward until their cirques meet, high, sharp pointed and steep sided peaks called horns form. That’s how the high relief in desert areas is reduced to low featureless plains called pediplains.

LANDFORMS AND THEIR EVOLUTION A fter weathering processes have had their actions on the earth materials making up the surface of the earth, the geomorphic agents like running water, ground water, wind, glaciers, waves perform erosion. LANDFORMS AND THEIR EVOLUTION A fter weathering processes have had their actions on the earth materials making up the surface of the earth, the geomorphic agents like running water, ground water, wind, glaciers, waves perform erosion. It is already known to you that erosion causes changes on the surface of the earth. Deposition follows erosion and because of deposition too, changes occur on the surface of the earth.

It is already known to you that erosion causes changes on the surface of the earth. LANDFORMS AND THEIR EVOLUTION A fter weathering processes have had their actions on the earth materials making up the surface of the earth, the geomorphic agents like running water, ground water, wind, glaciers, waves perform erosion. It is already known to you that erosion causes changes on the surface of the earth. Deposition follows erosion and because of deposition too, changes occur on the surface of the earth. As this chapter deals with landforms and their evolution ‘first’ start with the question, what is a landform?

Deposition follows erosion and because of deposition too, changes occur on the surface of the earth. It is already known to you that erosion causes changes on the surface of the earth. Deposition follows erosion and because of deposition too, changes occur on the surface of the earth. As this chapter deals with landforms and their evolution ‘first’ start with the question, what is a landform? In simple words, small to medium tracts or parcels of the earth’s surface are called landforms.

As this chapter deals with landforms and their evolution ‘first’ start with the question, what is a landform? Deposition follows erosion and because of deposition too, changes occur on the surface of the earth. As this chapter deals with landforms and their evolution ‘first’ start with the question, what is a landform? In simple words, small to medium tracts or parcels of the earth’s surface are called landforms. If landform is a small to medium sized part of the surface of the earth, what is a landscape?