Question 1

Multiple choice questions.

(i) In which of the following stages of landform development, downward cutting is dominated?

(a) Youth stage

(c) Early mature stage

(b) Late mature stage

(d) Old stage

(ii) A deep valley characterised by steep step-like side slopes is known as

(a) U-shaped valley

(c) Blind valley

(b) Gorge

(d) Canyon

(iii) In which one of the following regions the chemical weathering process is more dominant than the mechanical process?

(a) Humid region

(c) Arid region

(b) Limestone region

(d) Glacier region

(iv) Which one of the following sentences best defines the term 'Lapies'?

(a) A small to medium sized shallow depression

(b) A landform whose opening is more or less circular at the top and funnel shaped towards bottom

(c) A landform formed due to dripping water from surface

(d) An irregular surface with sharp pinnacles, grooves and ridges

(v) A deep, long and wide trough or basin with very steep concave high walls at its head as well as in sides is known as:

(a) Cirque

(c) Lateral Moraine

(b) Glacial valley

(d) Esker

Accepted Answer

1.(i) (a) Youth stage: In the youth stage of landform development, downward cutting or vertical erosion is dominant as rivers cut downwards to deepen their valleys.

(ii) (b) Gorge: A gorge is a deep valley characterized by steep step-like side slopes.

(iii) (a) Humid region: Chemical weathering is more dominant in humid regions due to abundant moisture facilitating chemical reactions.

(iv) (d) An irregular surface with sharp pinnacles, grooves and ridges: 'Lapies' refers to an irregular limestone surface with sharp pinnacles and grooves formed by chemical weathering.

(v) (a) Cirque: A cirque is a deep, long and wide trough or basin with very steep concave high walls at its head and sides formed by glacial erosion. — Step-by-step explanation:

(i) Youth stage rivers have high energy and erode vertically, creating deep valleys.

(ii) Gorges have steep, step-like side slopes formed by river erosion.

(iii) Chemical weathering requires moisture; hence humid regions favor it over mechanical weathering.

(iv) Lapies are distinctive karst features formed by dissolution of limestone creating sharp pinnacles and grooves.

(v) Cirques are amphitheater-like glacial basins with steep walls formed by glacier erosion.

Question 2

Answer the following questions in about 30 words.

(i) What do incised meanders in rocks and meanders in plains of alluvium indicate?

(ii) Explain the evolution of valley sinks or uvalas.
(iii) Underground flow of water is more common than surface run-off in limestone areas. Why?
(iv) Glacial valleys show up many linear depositional forms. Give their locations and names.
(v) How does wind perform its task in desert areas? Is it the only agent responsible for the erosional features in the deserts?

Accepted Answer

(i) Incised meanders in rocks and meanders in alluvial plains indicate the maturity of river systems and the presence of a stable base level allowing lateral erosion.

(ii) Valley sinks or uvalas evolve by the coalescence of several sinkholes due to continuous dissolution of limestone, forming larger depressions.

(iii) Underground flow is more common in limestone areas because limestone is highly permeable and soluble, allowing water to percolate and flow through underground channels.

(iv) Glacial valleys have linear depositional forms such as moraines and eskers; moraines are found at valley sides and ends, eskers are ridges formed by subglacial streams.

(v) Wind in deserts transports and deposits sediments, shaping erosional features like yardangs and dunes; however, water and temperature changes also contribute to desert erosion. — Each answer is concise and addresses the question directly:

(i) Meanders show river maturity and erosion patterns.
(ii) Uvalas form by merging sinkholes in karst terrain.
(iii) Limestone's permeability favors underground water flow.
(iv) Moraines and eskers are typical glacial deposits.
(v) Wind is a major but not sole erosional agent in deserts.

Question 3

Answer the following questions in about 150 words.

(i) Running water is by far the most dominating geomorphic agent in shaping the earth's surface in humid as well as in arid climates. Explain.

(ii) Limestones behave differently in humid and arid climates. Why? What is the dominant and almost exclusive geomorphic process in limestone areas and what are its results?

(iii) How do glaciers accomplish the work of reducing high mountains into low hills and plains?

Accepted Answer

(i) Running water is the most dominant geomorphic agent because it actively erodes, transports, and deposits sediments, shaping landscapes in both humid and arid climates. In humid climates, abundant rainfall leads to vigorous river systems that carve valleys and floodplains. In arid climates, although rainfall is scarce, episodic heavy rains cause flash floods that reshape desert landforms. Running water creates diverse features such as river valleys, canyons, and alluvial fans, making it a key agent in landscape evolution.

(ii) Limestones behave differently due to climate influence on weathering processes. In humid climates, chemical weathering dominates, leading to dissolution of limestone and formation of karst features like caves, sinkholes, and lapies. In arid climates, mechanical weathering is more prevalent, limiting karst development. The dominant geomorphic process in limestone areas is chemical weathering (solution), resulting in distinctive karst topography.

(iii) Glaciers reduce high mountains by processes of plucking and abrasion, eroding rock and transporting debris. They carve U-shaped valleys, cirques, and fjords, and deposit moraines and other glacial sediments. Over time, glaciers lower mountain heights and fill valleys with sediments, transforming rugged terrain into low hills and plains. — Detailed explanations:

(i) Running water's continuous movement shapes landforms by erosion and deposition.

(ii) Climate controls weathering type; chemical weathering in humid zones causes karst landscapes.

(iii) Glaciers erode mountains through mechanical action and deposit sediments, reducing elevation.

Question 4

Project Work

Identify the landforms, materials and processes around your area.

Accepted Answer

This project requires students to observe and identify local landforms such as hills, valleys, rivers, or any karst features. They should note the materials (rock types, soil) and geomorphic processes (erosion, deposition, weathering) active in their area. The project encourages practical understanding of geomorphology through field observation. — The project is designed to connect theoretical knowledge with real-world observation, enhancing learning by identifying natural features and processes locally.

Question 5

Which of the following best defines a natural hazard?

Accepted Answer

A natural event causing loss of life and property damage — Natural hazards are extreme natural events that can cause loss of life, property damage, and environmental degradation. They are part of Earth's natural processes but become disasters when they affect human life and property.

Question 6

Natural disasters occur due to the interaction between natural hazards and what other factor?

Accepted Answer

Vulnerable human populations — Disasters result from the interaction between natural hazards and vulnerable human populations. The hazard alone does not cause a disaster unless it impacts people and their property.

Question 7

Which of the following is NOT a correct category of natural hazards?

Accepted Answer

Technological hazards — Natural hazards are classified into geological, hydrological, meteorological, and biological hazards. Technological hazards are man-made and not part of natural hazard classification.

Question 8

Which natural hazard is caused by sudden release of energy in the Earth's lithosphere?

Accepted Answer

Earthquake — Earthquakes occur due to sudden release of energy in the Earth's lithosphere, generating seismic waves caused by tectonic plate movements along faults.

Question 9

The Richter scale is used to measure which aspect of an earthquake?

Accepted Answer

Magnitude — The Richter scale measures the magnitude of an earthquake, which quantifies the energy released at the source. The Mercalli scale measures intensity based on observed effects.

Question 10

Which of the following is an example of a geological hazard?

Accepted Answer

Volcanic eruption — Volcanic eruptions are geological hazards caused by magma reaching the Earth's surface, releasing lava, ash, and gases. Floods, heatwaves, and pest attacks belong to other hazard categories.

Question 11

Which of the following factors can trigger a landslide?

Accepted Answer

Heavy rainfall — Landslides involve downward movement of rock and soil on slopes, triggered by factors like heavy rainfall, earthquakes, or human activities. High temperatures and strong winds do not directly cause landslides.

Question 12

Avalanches are rapid flows of which material down mountain slopes?

Accepted Answer

snow — Avalanches are rapid flows of snow down mountain slopes, often triggered by fresh snowfall or vibrations such as earthquakes or human activity.

Question 13

Explain the difference between the Richter scale and the Mercalli scale used in measuring earthquakes.

Accepted Answer

The Richter scale measures the magnitude of an earthquake, which is the energy released at the source. The Mercalli scale measures the intensity based on observed effects and damage caused by the earthquake. For example, the Richter scale gives a numerical value while the Mercalli scale uses Roman numerals to describe intensity. — The Richter scale quantifies earthquake magnitude using seismograph data, while the Mercalli scale assesses intensity through human observations of damage and shaking. Both scales provide complementary information for earthquake analysis.

Question 14

Describe the causes and effects of volcanic eruptions.

Accepted Answer

Volcanic eruptions occur when magma from the Earth's mantle reaches the surface through volcanic vents. This releases lava, ash, and gases. The causes include tectonic plate movements and mantle plumes. Effects include destruction of nearby habitats, loss of life, air pollution from ash, and changes in climate due to released gases. For example, the eruption of Mount Pinatubo caused global temperature drops. — Volcanic eruptions result from internal Earth processes pushing magma upward. The effects are both local, such as lava flows destroying settlements, and global, such as climate impacts from aerosols. Understanding these helps in hazard assessment.

Question 15

Mapping earthquake-prone zones in India helps in which aspect of disaster management?

Accepted Answer

Risk assessment and preparedness — Mapping seismic zones identifies vulnerable areas, aiding in risk assessment and disaster preparedness. It does not prevent earthquakes or predict exact times but helps in planning and mitigation.

NATURAL HAZARDS AND DISASTERS: CAUSES, CONSEQUENCES AND MANAGEMENT

NATURAL HAZARDS AND DISASTERS: CAUSES, CONSEQUENCES AND MANAGEMENT — Study Notes

Introduction

Classification of Natural Hazards

Geological Hazards

Practice Questions — NATURAL HAZARDS AND DISASTERS: CAUSES, CONSEQUENCES AND MANAGEMENT

All 6 Chapters in India - Physical Environment