External Land Forming Processes

Introduction and Definition of Weathering

By the end of the lesson, the learner should be able to:
Define weathering as process of rock breakdown in situ
Explain denudation as collective term for external processes
Distinguish between weathering and other external processes
Identify weathering agents: heat, water, dissolved substances, plants and animals

Q/A session reviewing internal land forming processes from Form Two; Exposition of denudation concept and external processes; Definition of weathering and regolith formation; Discussion of weathering agents and their effects on rocks

Charts showing external vs internal processes, Rock samples showing weathering effects, Diagrams of weathering agents

Secondary Geography Form 3 Student's Book, Pages 41-42

External Land Forming Processes

Agents of Weathering
Factors Influencing Weathering

By the end of the lesson, the learner should be able to:
Explain how heat acts as weathering agent through temperature fluctuations
Describe water as weathering agent including dissociation into hydrogen and hydroxyl ions
Identify role of dissolved substances in increasing weathering ability
Analyze how plants and animals contribute to weathering processes

Detailed discussion of heat effects on rock surfaces and permafrost formation; Explanation of water dissociation and carbonic acid formation; Study of dissolved substances: pollutants, sulphur dioxide, organic compounds; Analysis of plant root penetration and animal burrowing effects

Rock samples, Temperature demonstration materials, Water pH testing materials, Examples of plant root damage to rocks
Climate charts, Relief diagrams, Rock samples of different colors and compositions, Examples from highland and lowland areas

Secondary Geography Form 3 Student's Book, Pages 42-44

External Land Forming Processes

Rock Structure, Texture and Physical Weathering Introduction

By the end of the lesson, the learner should be able to:
Explain rock structure as mode of jointing and planes of weakness
Describe texture as crystal size and its weathering effects
Define mechanical weathering as disintegration without chemical changes
Identify areas where physical weathering is common

Exposition of rock structure using Figures 3.1(a), (b) showing spheroidal weathering; Discussion of jointing patterns and resulting weathering types; Analysis of crystal size effects on weathering rates; Introduction to mechanical weathering in vegetation-free areas

Figures 3.1(a), (b), Rock samples showing different crystal sizes, Examples from Bunyore, Seme Hills, Sang'alo areas

Secondary Geography Form 3 Student's Book, Pages 45-47

External Land Forming Processes

Physical Weathering Processes - Block Disintegration and Exfoliation

By the end of the lesson, the learner should be able to:
Describe block disintegration through temperature changes and diurnal ranges
Explain exfoliation as peeling off of rock surfaces
Identify formation of exfoliation domes
Analyze conditions leading to these weathering processes

Detailed discussion of block disintegration using Figure 3.3; Analysis of desert temperature conditions and rock expansion/contraction; Study of exfoliation process using Figure 3.4; Examination of exfoliation dome formation using Figure 3.5

Figure 3.3 rock blocks, Figures 3.4 and 3.5 exfoliation examples, Temperature demonstration materials, Examples from desert regions

Secondary Geography Form 3 Student's Book, Pages 47-48

External Land Forming Processes

Physical Weathering - Granular Disintegration, Frost Action and Crystal Growth

By the end of the lesson, the learner should be able to:
Explain granular disintegration in heterogeneous rocks
Describe freezing and thawing effects in tundra and mountain regions
Identify frost action results: congelifraction, scree, talus
Analyze crystal growth in dry climates leading to alveoli and taffoni formation

Exposition of granular disintegration using Figure 3.6; Detailed discussion of frost action using Figure 3.7; Analysis of congelifraction and angular fragment formation; Study of crystal growth and crystallisation processes; Examples from Mounts Kenya, Kilimanjaro, Rwenzori and Ol Njorowa Gorge

Figure 3.6 granular disintegration, Figure 3.7 frost action, Figure 3.8 Ol Njorowa Gorge, Examples from East African mountains

Secondary Geography Form 3 Student's Book, Pages 48-50

External Land Forming Processes

Physical Weathering - Slaking and Pressure Release

By the end of the lesson, the learner should be able to:
Describe slaking as water uptake and loss in clay-containing rocks
Explain pressure release or unloading in exposed rocks
Identify areas experiencing these weathering processes
Analyze sheeting effects in granitic rocks

Discussion of slaking process in clay rocks during wet and dry seasons; Analysis of coastal Jurassic rocks examples: Miritini, Tudor, Port Reitz; Explanation of pressure release as denudation removes overlying rocks; Study of sheeting in granitic areas: Nyika plateau, Machakos, Maragoli, Bunyore

Examples from coastal Kenya, Granitic rock samples, Areas experiencing pressure release, Activity 3.4 practical demonstration

Secondary Geography Form 3 Student's Book, Pages 50-51

External Land Forming Processes

Chemical Weathering Processes - Solution and Hydrolysis
Chemical Weathering - Oxidation, Carbonation and Hydration

By the end of the lesson, the learner should be able to:
Define chemical weathering as actual decay involving chemical reactions
Explain solution affecting rocks with soluble minerals
Describe hydrolysis as major process in feldspar decay
Analyze chemical equations and products of hydrolysis

Exposition of chemical weathering in humid climates; Discussion of solution process and salt pan formation; Detailed analysis of hydrolysis chemical equation; Study of feldspar breakdown products: clay minerals, potassium carbonate, silica; Examples from North Eastern Kenya, Etosha Pan, Makgadikgadi

Chemical equation charts, Examples of salt pans, Rock samples containing feldspar, Areas showing hydrolysis: Wundanyi, Bunyore
Chemical equation demonstrations, Rock samples showing oxidation effects, Limestone samples, Examples of spheroidal weathering in basalt

Secondary Geography Form 3 Student's Book, Pages 51-53

External Land Forming Processes

Chemical Weathering Results and Biological Weathering

By the end of the lesson, the learner should be able to:
Identify formation of tors through deep weathering processes
Explain biological weathering through plant action
Describe animal contributions to weathering
Analyze human activities causing weathering

Analysis of tor formation using Figure 3.9; Study of examples: Bunyore, Maragoli, Amukura, Taita Hills, Lukenya, Mavoloni; Detailed discussion of tree root action using Figure 3.10; Examination of plant chemical contributions: algae, mosses, lichen; Analysis of animal effects: cattle pressure, burrowing, chemical excretions

Figure 3.9 tors examples, Figure 3.10 tree root action, Examples of biological weathering in local environment, Human activity examples

Secondary Geography Form 3 Student's Book, Pages 56-58

External Land Forming Processes

Biological Weathering - Human Activities and Significance of Weathering

By the end of the lesson, the learner should be able to:
Identify human activities causing weathering: deforestation, blasting, industrialisation
Explain acid rain effects from industrial emissions
Analyze burning and irrigation contributions to weathering
Discuss significance of weathering in soil formation, construction, tourism and economics

Study of human weathering activities using Figure 3.11 quarrying; Discussion of industrialisation effects: Carbon IV Oxide, sulphur dioxide emissions; Analysis of acid rain formation and corrosive effects; Examples from Copper Belt Zambia, Webuye Kenya; Study of agricultural burning and irrigation effects

Figure 3.11 quarrying, Examples of industrial weathering, Acid rain demonstration materials, Local examples of human-induced weathering

Secondary Geography Form 3 Student's Book, Pages 58-60

Mass Wasting

Introduction, Definition and Factors Influencing Mass Wasting

By the end of the lesson, the learner should be able to:
Define mass wasting as downward movement of weathered material under gravity
Distinguish between mass wasting and mass movement
Explain factors influencing mass wasting: slope, material nature, climate, vegetation
Analyze crustal forces and human activities effects

Q/A session reviewing weathering from previous chapter; Exposition of mass wasting concept and gravity influence; Discussion of water's role in overcoming resistance; Brain storming on factors affecting movement: slope angle, rock types, climate effects, vegetation role, human activities

Charts showing gravity effects, Slope demonstrations, Rock samples, Climate charts, Examples of human activities

Secondary Geography Form 3 Student's Book, Pages 53-54

Mass Wasting

Slow Mass Wasting Processes

By the end of the lesson, the learner should be able to:
Define soil creep as slow movement involving fine soil particles
Describe scree (talus) creep as angular waste rock movement on mountains
Explain solifluction as gravitational flow of water-saturated materials
Identify triggers, evidence and effects of slow mass wasting processes

Exposition of soil creep using Figure 4.1 showing effects and evidence; Discussion of triggering factors and infrastructure impacts; Study of scree creep using Figure 4.2 from mountain examples; Analysis of solifluction using Figure 4.3 in cold climates; Examples from Mount Kenya, Kilimanjaro, and local areas

Figures 4.1, 4.2, 4.3, Examples from mountains, Soil movement demonstrations, Cold climate examples

Secondary Geography Form 3 Student's Book, Pages 54-56

Mass Wasting

Rapid Mass Wasting - Earthflows, Mudflows and Avalanches
Landslides - Types and Characteristics

By the end of the lesson, the learner should be able to:
Describe earthflows in humid areas with shallow scars and terminal points
Explain mudflows as super-saturated material with high water content
Define avalanches as gravitational fall of ice and rock material
Analyze factors influencing rapid movements and compare characteristics

Study of earthflows using Figure 4.4; Analysis of mudflow formation, factors and examples from North Eastern Kenya; Discussion of avalanche characteristics in temperate regions; Comparison of movement speeds, water content and locations; Examples from volcanic slopes and arctic regions

Figure 4.4 earthflows, Mudflow examples, Avalanche examples from temperate regions, Factor comparison charts
Figures 4.5, 4.6 slump examples, Road cutting examples, Rock samples, Examples from Uganda and Kenya

Secondary Geography Form 3 Student's Book, Pages 56-57

Mass Wasting

Effects of Mass Wasting on Physical and Human Environment

By the end of the lesson, the learner should be able to:
Explain positive effects: soil fertility enhancement, tourist attractions, lake creation
Analyze negative effects: property damage, loss of life, soil erosion, permanent scars
Identify research centers and environmental awareness benefits
Study specific disaster examples and environmental conservation strategies

Comprehensive analysis using Figure 4.9 summary of mass wasting types; Discussion of positive effects: Miwa, Chemelil-Muhoroni soil fertility from Nandi Hills; Study of negative effects using Figure 4.10 Murang'a landslide; Analysis of major disasters: Kiina College 1968, Nyeri 1985, Murang'a 2000-2018; Environmental conservation strategies and research opportunities

Figures 4.9, 4.10, Soil fertility examples, Disaster case studies, Environmental conservation examples

Secondary Geography Form 3 Student's Book, Pages 60-61

The Hydrological Cycle

Introduction and Definition

By the end of the lesson, the learner should be able to:
Define hydrological cycle as endless circulation of water from oceans to atmosphere to land
Explain role of sun as energy source driving the cycle
Identify components: inputs, outputs, transfers and storages
Describe hydrological cycle as complete balanced system

Q/A session using questions about water disappearance and return; Discussion of water circulation from sky to land to ocean; Exposition of hydrological cycle definition; Analysis of Figure 5.1 showing complete cycle; Study of system components and energy source

Figure 5.1 hydrological cycle diagram, Water circulation demonstrations, System component charts

Secondary Geography Form 3 Student's Book, Pages 63

The Hydrological Cycle

Input and Output Processes

By the end of the lesson, the learner should be able to:
Identify precipitation as main input in various forms: dew, rainfall, mist, snow, fog
Explain evaporation as physical process of moisture loss to atmosphere
Describe transpiration as biological process of water loss from plants
Analyze factors affecting evaporation and transpiration rates

Exposition of precipitation forms and conditions for occurrence; Detailed discussion of evaporation process and factors: humidity, temperature, wind, sunshine hours, water characteristics; Analysis of transpiration through stomata and lenticles; Study of evapotranspiration as combined process

Precipitation examples, Evaporation demonstration materials, Plant samples showing stomata, Factor analysis charts

Secondary Geography Form 3 Student's Book, Pages 63-65

The Hydrological Cycle

Internal Transfer Processes

By the end of the lesson, the learner should be able to:
Explain interception as first contact of rain with vegetation
Describe runoff as overland flow when ground cannot absorb water
Define infiltration as vertical water absorption through soil pores
Distinguish percolation as movement through underlying rock layers

Study of interception storage and through fall processes; Analysis of surface storage and ground saturation; Discussion of runoff conditions and overland flow; Examination of infiltration capacity and factors; Study of percolation leading to underground water storage

Vegetation interception examples, Runoff demonstration materials, Soil infiltration samples, Percolation process diagrams

Secondary Geography Form 3 Student's Book, Pages 65-66

The Hydrological Cycle
ACTION OF RIVERS
ACTION OF RIVERS

Storage Processes and Significance
Definition of Terms Related to Rivers
River Erosion Processes

By the end of the lesson, the learner should be able to:
Identify surface water storage: seas, oceans, lakes, swamps
Describe ground water storage above impermeable rocks creating water table
Explain cryosphere as water stored in ice-covered regions
Analyze significance of hydrological cycle in ecological balance and distribution

Discussion of surface water storage through rivers to seas and lakes; Analysis of ground water formation through percolation and infiltration; Study of cryosphere as fresh water store; Examination of cycle significance: ecological balance, rainfall formation, atmospheric unity, oxygen-carbon cycle, water distribution

Water storage examples, Ground water table diagrams, Ice storage examples, Significance analysis charts
Maps of Kenya, river system charts, textbooks
Water containers, sand, rock samples, demonstration materials

Secondary Geography Form 3 Student's Book, Pages 66-67

ACTION OF RIVERS

River Transportation and Deposition
Youthful Stage Features

By the end of the lesson, the learner should be able to:
Describe transportation processes: solution, suspension, saltation, traction. Explain deposition factors and conditions.

Practical demonstration of transportation methods. Discussion of deposition conditions when river energy decreases. Group activity on load classification.

Containers, different sized particles, water, magnifying glasses
Clay/plasticine, topographical maps, pictures of waterfalls, drawing materials

KLB Secondary Geography Form 3, Pages 72-73

ACTION OF RIVERS

Mature Stage Features
Old Stage Features - Alluvial Fans and Flood Plains
Old Stage Features - Meanders and Ox-bow Lakes

By the end of the lesson, the learner should be able to:
Describe wider valleys, gentler gradients, river bends, bluffs. Explain lateral erosion becoming dominant over vertical erosion.

Comparison of youthful and mature features. Drawing cross-sections showing valley widening. Discussion of transitional characteristics.

Comparison charts, cross-section diagrams, colored pencils
Sand, water, modeling trays, maps showing flood plains, diagrams
Stream tables, sand, water, sequential diagrams, pictures of ox-bow lakes

KLB Secondary Geography Form 3, Page 81

ACTION OF RIVERS

Old Stage Features - Levees, Braided Channels, and Deferred Tributaries
Delta Formation and Types

By the end of the lesson, the learner should be able to:
Describe natural levee formation during floods. Explain braided channel development and deferred tributary formation.

Drawing levee cross-sections. Discussion of raised river beds and flooding problems. Analysis of braided patterns during dry seasons.

Cross-section diagrams, aerial photographs, flood plain maps
Maps of river deltas, diagrams of delta types, aerial photographs

KLB Secondary Geography Form 3, Pages 84-85

ACTION OF RIVERS

River Profile Summary

By the end of the lesson, the learner should be able to:
Summarize features along youthful, mature, and old stages. Compare dominant processes and resultant landforms at each stage.

Creating comprehensive river profile diagrams. Consolidation exercise comparing all stages. Tabulation of features by river stage.

Large drawing paper, colored pencils, summary charts, profile diagrams

KLB Secondary Geography Form 3, Page 89

ACTION OF RIVERS

River Capture

By the end of the lesson, the learner should be able to:
Define river capture, pirate river, misfit river, elbow of capture, wind gap. Describe capture process and conditions. Explain Kenyan examples: Tiva-Galana and Sondu-Miriu captures.

Drawing river capture process step-by-step. Detailed case study of Kenyan river captures. Map analysis of capture sites and resultant features.

Maps of Kenya, capture process diagrams, case study materials

KLB Secondary Geography Form 3, Pages 85-86

ACTION OF RIVERS

River Rejuvenation

By the end of the lesson, the learner should be able to:
Define river rejuvenation and distinguish dynamic vs static rejuvenation. Describe resultant features: river terraces, incised meanders, rejuvenation gorges, knick points.

Discussion of rejuvenation causes (base level changes, increased discharge). Drawing rejuvenation features with examples from coastal Kenya rivers.

Rejuvenation feature diagrams, pictures of incised meanders, maps of coastal Kenya

KLB Secondary Geography Form 3, Pages 86-89

ACTION OF RIVERS

Drainage Patterns
Drainage Systems

By the end of the lesson, the learner should be able to:
Identify and describe dendritic, radial, centripetal, parallel, fault-guided, and trellis drainage patterns. Explain formation conditions and give Kenyan examples.

Drawing different drainage patterns. Analysis of Mt. Kenya radial drainage and Rift Valley centripetal patterns. Pattern recognition exercises.

Pattern diagrams, maps of Mt. Kenya and Rift Valley, colored pencils
Geological maps, drainage system diagrams, cross-sections

KLB Secondary Geography Form 3, Pages 90-92

ACTION OF RIVERS

Significance of Rivers - Positive Effects

By the end of the lesson, the learner should be able to:
Explain rivers' roles in water supply, irrigation, transport, HEP generation, port facilities, building materials, boundaries, fishing, tourism.

Discussion of urban water supplies from rivers. Analysis of HEP projects and irrigation schemes. Review of river-based economic activities.

Maps of water systems, pictures of dams and ports, economic activity charts

KLB Secondary Geography Form 3, Pages 94-96

ACTION OF RIVERS

Significance of Rivers - Negative Effects and Water Conservation

By the end of the lesson, the learner should be able to:
Describe flooding problems, communication barriers, waterborne diseases. Explain Water Act provisions for conservation and access.

Discussion of flood disasters and health issues. Analysis of communication problems caused by rivers. Review of water resource management principles.

Pictures of floods, case study materials, Water Act summary

KLB Secondary Geography Form 3, Pages 96-97