Geography Grade 8 - Comprehensive Notes

Geography Grade 8 Notes

Educational Publications Department

• Website: www.edupub.gov.lk

Publication Information

• First Print - 2016

• Second Print - 2017

• Third Print - 2018

• Fourth Print - 2019

• All Rights Reserved

• ISBN 978-955-25-0136-4

• Published by Educational Publications Department

• Printed by Saraswathi Publications

Messages and Foreword

• Message from the Hon. Minister of Education: Focuses on technological changes, new challenges, career opportunities, and the importance of education for becoming productive citizens. Acknowledges the role of free education and the need to value the government's investment in education.

• Foreword: Highlights the complexity of educational objectives in the modern world due to economic, social, cultural, and technological development. Emphasizes that textbooks are not just learning tools, but contribute to the development of conduct, attitudes, and values. Stresses the importance of utilizing and protecting the provided textbooks.

Publication Details

• Monitoring and Supervision: W. M. Jayantha Wickramanayaka, Commissioner General of Educational Publications

• Direction: W. A. Nirmala Piyaseeli, Commissioner (Development)

• Co-ordination: Anupa Madhupani Weerarathne, Assistant Commissioner, J. W. Rumesh Jayalath (2019), Assistant Commissioner

• Panel of Editors and Writers: Lists various professors, lecturers, teachers, and editors from different educational institutions.

• Language Editor: M. P. A. M. Weerarathne

• Cover Design: R. A. Yureka Dilrukshi

• Type Setting (Formatting): Abisheka Ranasinghege, R. A. Yureka Dilrukshi

Content Overview

• The textbook covers the following units:

  • The Solar System

  • Uniqueness of the Earth as a habitat of the living beings

  • The basic features of 1: 50 000 topographic maps of Sri Lanka

  • South Asia

Unit 1: The Solar System

Overview

• Objective: To study the composition and functions of the solar system.

• The solar system consists of the sun, eight planets, asteroids, dwarf planets, and natural satellites.

• Formed 4600 million years ago from dust particles and gases.

Stars

• Celestial bodies that emit light and heat, making them sources of energy.

• Planets, natural satellites, and asteroids do not emit light but reflect sunlight.

Composition

• The Sun: Main body of the solar system.

• Planets: Largest celestial bodies.

• Dwarf Planets: Smaller planets.

• Natural Satellites: Orbit the planets.

• Other Rock Particles/Debris: Asteroids, comets, meteoroids.

The Sun

• Main source of energy for life on Earth.

• Located at the center of the solar system.

• Core temperature: $15,000,000^{\circ}C$

• Surface temperature: $6000^{\circ}C$

• Specific features:

  • Holds 99.86% of the total mass of the solar system.

  • Extent is 109 times the diameter of Earth.

  • Diameter is 1.4 million kilometers.

  • Source of energy and heat for all planets.

  • Solar storms occur, causing flames to burst out.

  • Rotates around its own axis in 25.4 Earth days.

Planets

• Eight main planets: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.

• Asteroid belt located between Mars and Jupiter.

• Divided into inner and outer planets.

Inner Planets

• Located between the Sun and the asteroid belt.

• Composed of rocks, silicate, and metal materials.

• Includes Mercury, Venus, Earth, and Mars.

Mercury

• Closest planet to the Sun.

• Smallest planet in the solar system; slightly larger than Earth’s moon.

• High temperature (approx. $167^{\circ}C$) due to proximity to the Sun and slow rotation.

• Craters on the surface due to volcanic eruptions.

• No atmosphere, high risk of asteroid and meteor impacts.

• No satellites.

Venus

• Second planet from the Sun.

• Closest planet to Earth.

• Highest surface temperature: $464^{\circ}C$.

• Main gas: Carbon dioxide (96%).

• Slightly smaller than Earth.

• Brightest planet in the night sky due to reflection of sunlight by thick clouds.

• Rotates from East to West.

• Visible as the Morning Star and Evening Star.

• No satellites.

Earth

• Third planet from the Sun.

• Largest among the inner planets.

• Called the Blue Planet due to its appearance from space.

• Only planet known to support life.

• Reasons for life: presence of water, suitable atmosphere, gravitational force.

• One natural satellite: the Moon.

Mars

• Fourth planet from the Sun.

• Called the Red Planet.

• Visible with the naked eye.

• Thin atmosphere, mainly carbon dioxide.

• Two satellites: Phobos and Deimos.

Outer Planets

• Located outside the asteroid belt.

• Gaseous composition (Hydrogen and Helium).

• Includes Jupiter, Saturn, Uranus, and Neptune.

Jupiter

• Fifth planet from the Sun and the largest in the solar system.

• Diameter: $142,984 \text{ km}$, ten times the diameter of Earth.

• Black stripes and bright regions on the surface.

• Highest gravitational force among planets.

• 67 natural satellites.

Saturn

• Sixth planet from the Sun.

• Second largest planet, about nine times the size of Earth.

• Has rings made of ice particles.

• 62 natural satellites.

Uranus

• Seventh planet from the Sun.

• Third largest planet.

• Thin set of rings.

• 27 satellites.

Neptune

• Eighth and farthest planet from the Sun.

• Blue in color.

• Four times larger than Earth.

• Extremely cold.

• 14 natural satellites.

Quick Facts Chart (Table 1.1)

Dwarf Planets

• Small planets with no fixed orbits.

• Five identified: Pluto, Eris, Ceres, Makemake, Haumea.

• Scientists believe there may be more.

Natural Satellites

• Celestial objects orbiting main planets.

• 173 satellites of the main planets and 8 of the dwarf planets.

Number of Natural Satellites Chart (Table 1.2)

Asteroids

• Rock fragments left over from the formation of the solar system.

• Made of hard rocks with different shapes and sizes.

• Millions found between the orbits of Mars and Jupiter.

Beliefs Related to the Solar System

• Various beliefs exist regarding the influence of celestial bodies on people's lives.

• Examples: worshiping the Sun and Moon as gods, astrology, ritualistic activities, horoscopes, ceremonies based on the Sun and Moon, traditional farming activities, influence of the Moon on herbal medicine.

New Knowledge about the Solar System

• Early exploration without developed science.

• Galileo Galilee: First to use a telescope to observe the universe in 1610 A.C.

• Claudius Ptolemy, Nicolas Copernicus, Johannes Kepler, and Isaac Newton also contributed.

• 1957: USSR launched the first artificial satellite.

• NASA established by the United States, launching several satellites.

• 1957 A.D USSR (Russia) launched the first artificial satellite.

• 2006: Pluto declared a dwarf planet; solar system now considered to have eight planets.

• Recently: "Caltech" Astronomical Institute in U.S.A. revealed information about a possible ninth planet (Planet 9), which is ten times larger than Earth but not yet confirmed.

Unit 2: Uniqueness of the Earth as a Habitat of Living Beings

Overview

• Objective: Identify facts about Earth's uniqueness in the solar system.

• Earth has a spherical shape with an area of 510 million square km.

• Equatorial diameter is 42 km longer than the polar diameter, so it is not a perfect sphere.

  • Equatorial diameter: $12756 \text{ km}$

  • Polar diameter: $12714 \text{ km}$

Location of the Earth in the Solar System

• Earth is the third planet from the Sun.

• Average surface temperatures:

  • Mercury: $167^{\circ}C$

  • Venus: $464^{\circ}C$

  • Earth: $15^{\circ}C$

  • Neptune: $-200^{\circ}C$

Factors Contributing to Earth as a Habitable Planet

• Intermediate temperature.

• Existence of water.

• Existence of gravitational force.

• Presence of an atmosphere with favorable gases and water vapor.

• Occurrence of rotation and revolution.

• Earth is currently believed to be the only planet with life.

Latitudes and Longitudes

• Imaginary lines drawn on the globe to identify locations.

Latitudes

• Equator: zero (0°) latitude, separates the Northern and Southern Hemispheres.

• Northern latitudes: run parallel to the equator up to 90° in the Northern Hemisphere.

• Southern latitudes: run parallel to the equator up to 90° in the Southern Hemisphere.

• Circles of latitude become smaller towards the poles.

Longitudes

• Imaginary lines extending from the North Pole to the South Pole.

• Greenwich Meridian: 0° longitude, runs through Greenwich, England.

• Eastern longitudes: up to 180° east from the Greenwich Meridian.

• Western longitudes: up to 180° west from the Greenwich Meridian.

• 180° longitude is not classified as eastern or western.

Rotation of the Earth

• The movement of the Earth around its own axis.

• Earth rotates from West to East.

• Axis is tilted at an angle of 23.5° to the orbital plane.

• The Earth takes 23 hours and 56 minutes for a complete rotation around its axis, though a day is considered 24 hours.

Occurrence of Day and Night

• Rotation results in day and night and regional time differences.

• Half of the Earth facing the Sun has day, while the other half has night.

• Time changes according to longitude; when it is 12:00 noon on a longitude, the Sun is overhead.

• The Sun rises earlier in eastern countries.

• The Earth moves 360° during 24 hours, 15° per hour, and 4 minutes to travel within two longitudes, creating time differences across the Earth.

Standard Time

• Earth divided into 24 regions or time zones.

• Large countries like the United States, Canada, Australia, and Russia use time zones relevant to their particular region.

• The day breaks at 12.00 midnight.

• The Greenwich meridian is considered as the 0° longitude.

  • Adding one hour for every 15 longitudes towards east from Greenwich Meridian.

  • Reducing one hour for every 15 longitudes towards west from Greenwich Meridian.

• International Date Line (IDL) based on 180° longitude has a one-day difference on either side.

Revolution of the Earth

• Earth's movement around the Sun is called revolution.

• The orbit is the path of the Earth around the Sun.

• One complete revolution takes 365 days and 6 hours.

• 365 days are considered one year; the extra 6 hours accumulate, creating a leap year every four years with 366 days.

• Axis inclination of 23.5° affects where the Sun is directly overhead, changing day and night lengths by latitude and creating seasonal changes in upper latitudinal regions.

Equinox

• The Sun is directly over the equator on March 21st and September 23rd.

• March 21st: Vernal (Spring) Equinox.

• September 23rd: Autumnal (Fall) Equinox.

• During equinoxes, day and night are equal (12 hours) in all latitudes.

Solstice

• The Sun is directly over the Tropic of Capricorn on December 22nd: Winter Solstice.

• The Sun is directly over the Tropic of Cancer on June 21st: Summer Solstice.

• June 21st: longer daytime in the Northern Hemisphere; shorter daytime in the Southern Hemisphere.

• December 22nd: longer daytime in the Southern Hemisphere; shorter daytime in the Northern Hemisphere.

• Solstices and equinoxes are directly connected with the seasons of the year as the path of the Sun crosses different latitudes at different times.

Main Seasons

• Seasonal differences are more clearly observed away from the tropics.

Summer

• Highest temperature, longer daytime.

• Difficult period for living beings due to high temperature.

• Northern Hemisphere: starts in June; Southern Hemisphere: starts in December.

Autumn

• Temperature decreases gradually.

• Northern Hemisphere: starts in September; Southern Hemisphere: starts in March.

• Leaves begin to fall.

Winter

• Temperature decreases to its maximum level.

• Northern Hemisphere: starts in December; Southern Hemisphere: starts in June.

• Longer night periods.

• Leaves completely fall off trees; snow falls in many areas.

Spring

• Temperature gradually rises up.

• Northern Hemisphere: starts in March; Southern Hemisphere: starts in September.

• Snow and ice begin to melt.

• Tender leaves appear on dormant trees; flowers bloom and bear fruits.

Air/Atmosphere

• The atmosphere is composed of various gases held by Earth's gravitational pull.

• Wind is the air in motion.

• It contains gases, water vapor, dust, and salt particles.

Importance of the Atmosphere

• Essential for the existence of life.

• Retains water vapor and maintains the water cycle.

• It causes the process of precipitation.

• Controls entry of harmful ultraviolet rays through the ozone layer.

• Controls falling meteors.

• Regulates temperature on the Earth's surface.

Composition of Gases in Earth’s Atmosphere (Table 2.1)

Water

• Found on earth in different forms.

  • Liquid: Water

  • Solid: Ice

  • Gas: Water vapor

• 71% of total land area or 3/4 of the Earth is covered by water.

Distribution of Water on Earth

• Oceans and Seas: 97.5%

• Ice caps and Snow: 1.97%

• Ground water: 0.5%

• Fresh water: 0.03%

• Water interchanges cyclically between the land and the atmosphere: water cycle or hydrological cycle (H2O cycle).

Importance of Water

• Essential for living beings.

• Domestic purposes.

• Agricultural activities.

• Various industries.

• Transportation.

• Generating electricity (hydro-electricity).

• Recreational activities (water sports).

Unit 3: South Asia

Overview

• Objective: Study the location and landscape of the South Asian Region.

• Characteristics: South Asia is a unique geographical region due to its physical, human, and geographical features.

• Diversity: The region ranges from the Sundarban marshy land to Mount Everest.

• Climate and vegetation: Includes extremely cold and warm areas, dense forests, and grasslands.

Location

• Bounded by: The Himalayas in the North, the Indian Ocean in the South, the Bay of Bengal in the East, and the Arabian Sea in the West.

• Absolute Location: Spreads from 0° to 38° North latitude and 60° to 100° East longitude.

• Land Area: South Asia comprises 3% of the total land area of the Earth.

Constituent Countries

• India

• Pakistan

• Nepal

• Bangladesh

• Bhutan

• Maldives

• Sri Lanka
  *Note: Nicobar and Andaman Islands belong to the South Asian region. Afghanistan has been awarded the membership of the SAARC, but geographically it belongs to Central Asia.

General Characteristics

• Location: North of the equator, having a tropical climate.

• Geography: Some countries have coastal belts, while Nepal and Bhutan are landlocked.

Landscape of the South Asian Region

• Landscape: The region has diverse physical and human landscapes, divided into six categories based on specific features.

• Definition: Landscape refers to the physical environment in a specific area and the total landscape created by human activities.

Landscape Categories

• Mountain landscape

• Valley landscape

• Coastal landscape

• Rural landscape

• Industrial and urban landscape

• Desert landscape

I. Mountain Landscape

• Presence: Except for the Maldives, all countries in the South Asian region have mountain landscapes.

• Examples: India has the Himalayan mountain range, Pakistan has the Hindu Kush and Sulaiman Ranges, and Sri Lanka has the Central hills.

Focus: Himalayan Mountain Range

• Composition: The Kunlunshan Himalaya and Karakoram mountain range together form the Great Himalayan Range.

• Features: Mountains, spurs, deep gorges, passes, highlands, plateaus, and gaps.

• Height: Approximately 8000 meters above mean sea level.

• Spread: Extends about 2500 km in length.

• Peaks: Nine out of the 14 highest peaks in the world are located in the Himalayan range.

• Climate: Varies from polar to tropical climates.

• Vegetation: From snow-capped peaks to warm valleys, with dry climates in areas surrounded by mountain ranges. Wide range of animal and plant species.

• Ethnic Groups: Several Mongoloid tribal groups inhabit the Himalayas, including Bhutia, Khasa, Darad, Lepcha, and Sherpas.

• Adaptations: physical features and lifestyle adapted to mountainous physical environment, e.g., flat, broad feet, strong legs, muscular arms, and lungs adapted to lower oxygen percentages.

• Human Activities: Specific to snowy mountainous landscapes include mountaineering, skiing, and tourism.

• Houses: Built with raw materials like stones, saw dust, clay, and timber and thatched roofs. Houses are constructed so as to withstand relief and the climatic changes (e.g., living in cluster settlements).

• Crops: rice, wheat, corn, green-gram, millet, and vegetables

• The region's inhabitants consumes meat from hunting, yams from forests, and honey and trades such items for money.

II. Valley Landscape

Different to mountainous landscape, river valley, and soil composition determine agriculture and living style.

*Notable Locations:

• India: The Ganges Valley

• Pakistan: The Indus River Valley

• Sri Lanka: The Mahaweli and Kelani River Valleys

Focus: The Ganges Valley

• Extent: Begins in the Himalayas, extending about 2510 km to the Bay of Bengal.

• Features: Undulating lands, braided rivers, meanders, plains, flood plains, sand sheets, and wide river valleys.

• Physical features: areas above 200 meters are rarely found in this valley.

• Cultural factors: Places of worship of Buddhism, Hinduism, and other religions. The river is considered sacred by Hindus, and they enhance the cultural landscape.

• Human Activities: Agriculture is the people main activity; paddy, wheat, and sugar cane dominates production.
  *(Climate effect: Extreme conditions affect crops, leading to adapted cultivation methods).
  *Density-population: The region is densely populated. Higher population contributes to development of the agricultural and industrial sectors.

• Industry: Delhi, Patna, Agra, Varanasi, Kolkata and Dhaka.

Coastal Landscape

• Extent: The South Asian region has a very long coastal belt; all countries except Nepal and Bhutan have access. Sri Lanka and The Maldives illustrate with excellent coastal landscapes.

• Features: Sand bars, lagoons, bays, points, coral reefs, beaches, and mangroves.

  • Geography: comprising of coral reefs and atolls (Maldives with 1200 islands and only 200 inhabited).

  • Economy and Culture: Fishing and tourism dominate economic culture.

  • Economy: Selling fish; production of canned fish, Maldive fish, and dried fish; sea shells and ornaments production.

  • Tourism promotion includes shallow seas with coral reefs, coastal belts, sandy beaches, and other attractive natural factors.

Rural Landscape

Features: Rural landscape plays a prominent feature in the South Asian region; Dry Zone (Sri Lanka): best illustrates.
Rural settlement includes river access, economic crops, planned cities, and irrigation projects contribute to the transformation of this settlement.

Features Include

• Low population density with agriculture and fisheries. Features: settlement patterns, agricultural-based industries. Chenas are a special feature in this settlement. *Economy: The region grows grains, vegetables, and fruits. Livestock farming (cows and bulls) is popular in this region.

  • The village has been formed based on the tank at the centre and paddy is the main economic crop.* Indigenous people maintain social, cultural, an ancestral traditional settlement.

Industrial and Urban Landscape

The urban industry landscape is now a popular part of South Asia in locations like Mumbai, Karachi, and Colombo.
Physical and social attributes
*Roadways.
*Residential, industrial, and administrative zones.
*Facilities attract people to facilitate economic prosperity.

Desert landscapes

• Known regions: Rajastan (Indo-Pak border region)

• Desert terrain includes ground water in the aquifer.

• Dry environments with very limited water include very deep plant root systems, deep well location used as Oasis', and nomadic people who rely on livestock.

Unit 4: The Basic Features of 1: 50 000 Topographic Maps of Sri Lanka

Objective

• The objective of this lesson is to study several basic features of 1: 50 000 topographic maps of Sri Lanka.

Overview

• Maps present various features on the Earth’s surface.

• Topographic maps represent both natural features and man-made features.

• Colors, letters, and symbols represent these features.

• Maps are useful for understanding the landscape.

• Correct map reading is crucial.

Natural vs Man-made Features

• Natural Features: Mountain ranges, Rivers, Forests, Plains, Grasslands

• Man-made Features: Main roads, Buildings, Tanks, Farmlands, Canals

• Natural features are also called physical features; man-made features are cultural features.

Scale of 1: 50 000 Topographic Maps of Sri Lanka

• Scale: 1:50 000 (1 cm on the map = 50,000 cm or 0.5 km on the ground)

• Implication: 1 kilometer on land is shown by 2 centimeters on the map

• The scale is useful for determining the correct distance between two places on the map.

Size and Division of the Map

• Length: From Point Pedro to Dondra Head ($432 \text{ km}$) (864 cm on map)

• Width: From Colombo to Sangamankanda Point ($224 \text{ km}$) (448 cm on map)

• Actual Map Size (if drawn as a whole): $8.64 \text{m}$ in length and $4.48 \text{m}$ in width. Difficult to use at this scale, so the map divided into 92 parts or map sheets.

• Each part is known as a map sheet.

• Each map sheet assigned a name and sheet number (Example: Kandy - 54).

Physical and cultural Features in Topographic Maps

• Topographic maps include physical and cultural features. A study on segment number 91 Mathara sheet of the 1:50000 topographic map shows the study.

• To study information, you must consider the map key that includes features. Most topographical maps contain such a key.

Physical Features

• Relief Features: Mountain ranges, highlands, plains, slopes, valleys, and gaps

• Represented using contour lines.

Contour Lines

• Definition: Lines drawn on maps joining places with equal height above sea level.

• Characteristics: Every contour line has a specific value. The interval between two contour lines is equal. Contour line interval in 1: 50 000 topographic maps of Sri Lanka is 20 meters.

Representing the Topographical Features in Map

• Mountain range (High land spreads with multiple peaks shown by the line-segments of equal height),

• Conical Hill(A small high ground in the shape of a cone in the flat land indicated by circle contour lines) and

• Spur (A part of high land which protrudes towards a low land represents elongated narrowing lines).

*Definition Valley- Low land between two high lands (represented with the contour lines that extend toward the highland).
*Low (Land between a Mountain/High Land peak)

Cultural Features

• These cultural features have been shown in the maps by various symbols and colours.

• Cultural landscape: It Contains symbols, key codes, features and physical foundations
  Administrative boundaries (Provincial, District), Road networks, Irrigation channel & tanks

• Administrative Boundaries are classified for a region and they can be identified with district and provincial boundaries.

• Road networks are the highways and transit access; in maps, the "A" roads are the most notable.
  Railway access and networks show the main channels for transports in Maps.
  *Tanks-collect the water on land and distribute water using roads and channels. in Maps, tank bunds are marked with yellow.