Unit 3: Topographical Maps

Map Symbols

A symbol is a marking, sign or object that represents something.

Area Symbols

• Spaces that are contained within boundaries and are used to represent things like dams and residential areas

• Areas can be regular (Shapes like circles, triangles and rectangles) or they can be irregular (Like the shape of a lake)

Point Symbols

Used to represent buildings like shops or schools

Line Symbols

Used to represent structures like roads, rivers and railways

Natural Features

• Not man-made

  • Part of the environment

  • Occurs naturally

• Provides resources like paper, building materials and furniture

• Typical Natural Features

  • The sea, Natural bays, Shores, Islands

  • Mountains

  • Rivers, Lakes, Natural dams

  • Bushes, Forests, Vegetation

Constructed Features

• Man-made

  • Does not occur naturally

• Caters to our needs

  • Eg. Roads help us travel from one place to another easier

• Typical Constructed Features:

  • Roads, Railways, Lines, Airports

  • Settlements

  • Dams

  • Purification Plants

Height Clues

• Indicators or marks of heights

• Two symbols that represent height are:

  • Spot heights

    • Denote the exact height of the land

    • Shown by a small black dot with a height reading above sea level next to it

  • Trig beacons

    • Shown by a triangle

    • The number above the triangle is the number of the trig beacon while the actual height above sea level is given next to the tringle

  • Surveyors measure both

• Main height clues are the contour lines

  • Close together = Steep

  • Far apart = Gradual

River Valley

• A valley formed by flowing water.

• It is usually V-shaped.

• The exact shape will depend on the characteristics of the stream flowing through it.

• Rivers with steep gradients, as in mountain ranges, produce steep walls and a bottom.

• Shallower slopes may produce broader and gentler valleys.

Hill

• A hill is a landform that extends above the surrounding terrain.

• Hills often have a distinct summit and are generally lower and less steep than mountains.

Mountains

• A mountain is a large landform that rises up quite abruptly above the surrounding land in a limited area, usually in the form of a peak that can reach quite a high altitude.

• A mountain is generally steeper than a hill.

  • (Mountain ranges can stretch for very long distances.)

Ridge

• A ridge is a long, narrow raised land formation with sloping sides, usually formed by the meeting of two faces of a mountain.

Spur

• A spur is a long, gently sloping strip of ground that runs down from a hill to lower ground.

• Spurs often provide access to and from the high ground, for walkers and for roads.

Types of Scales

• Line Scales

  • A line scale on a map is a scale that shows you in specific, accurate-drawn units of measurement how many units of that measurement (e.g. cm) represent how many units of another measurement (e.g. km) on the ground

  • This means that if you would have taken your ruler and measure the first part of your line scale you would see that it is 1 cm on your ruler. This means that 1 cm on the map equals 250 km in reality.

• Ratio Scale

  • A ratio scale tells us how many units of measurement (usually cm) on the Earth's surface are equal to one unit of the same measurement (cm) on a map.

• Word Scale

Converting Scales

• In some cases, it is easier to use a specific scale and therefore you need to be able to convert scales.

• All scales say the same thing but look different.

• Eg.

  • 1 : 1 500 000

  • 1cm = 1 500 000cm

  • 1 500 000cm / 100 000 = 15km

Large - Scale Maps

• 1 cm on a map represents less ground distance than on small-scale maps

  • Eg. 1:50 000

• Features appear larger and are generally more detailed

• Large-scale maps are commonly used to represent ground distances on local maps

  • Eg. Brits, as shown in the map

Small - Scale Maps

• 1 cm on a map represents more ground distance than on large-scale maps

  • Eg. 1:1 485 000

• Features are usually less detailed

• Small-scale maps are commonly used represent ground distances on world and regional maps

  • Eg. South Africa.

Coordinates

• A geographic coordinate is the point at which a line of latitude (horizontal) intersects a line of longitude (Vertical).

• The line of latitude is always written first, followed by the line of longitude.

• There are 60 minutes in one degree and 60 seconds in one minute.

• This detailed breakdown allows every point, place or feature on Earth to be given a position or geographic coordinate.

  • Degrees (°)

    • To show degrees, we use this symbol: º.

    • So, we can write 10 degrees as 10°.

  • Minutes (')

    • Each degree is divided into 60 minutes.

    • To show minutes, we use this symbol: '.

    • So, we can write 10 minutes as 10'.

  • Seconds (")

    • To be even more precise, each minute is divided into 60 seconds.

    • To show seconds, we use this symbol: ".

    • So, we can write 10 seconds as 10".