this 107 page document contains every topic needed for matric finals! it covers mapwork, settlements, economy, fluvial processes, geomorphology, climate and everything else included in the sags document.
Map work techniques
SCALE, DISTANCE, AREA
Word scale: the map distance and the ground distance it represents are written
in words (eg. 1 cm represents 500m)
Representative fraction: the unit of the map distance is the numerator and the
equivalent ground distance is the denominator (eg. 1/50 000)
Ratio scale: the unit of map distance is shown in relation to the equivalent
horizontal distance on the ground (eg. 1:50 000)
Line scale: also called a linear or graphic scale. The ratio between the map
distance and the equivalent ground distance is shown as a scale bar
1:50 000 = topographic maps
1cm on the map represents 50 000 cm in reality
1 cm represents 500m
1 cm represents 0,5km
- Times by 0,5 or divide by 2 to get from cm to km
1:10 000 = orthophoto maps
1cm on the map represents 10 000 cm in reality
1 cm represents 100m
1 cm represents 0,1km
- Times by 100 to get from cm to m
,NB: a small scale map (large number in ratio scale) shows a larger area with less
detail
Estimating area of a rectangle
- Length x breadth
- Convert to same units
Hectares
1 ha (hectare) = 10 000m²
100 ha = 1km²
- To convert km² to ha : multiply answer by 100
- To convert m² to ha : divide answer by 10 000
, DIRECTION
Direction = the description of the position of one place in relation to another
True north
- All lines of longitude converge at this point
Magnetic north
- Earth's magnetic field pulls magnetic needle of a compass
- Drifts over time
- Will be given on a map
True bearing
- Angle from one place to another measured from true north line
- Is read clockwise from 0* on North-South line
, Magnetic declination
- Angular difference between magnetic north and true north
- MD can be calculated as long as angle between true north and magnetic
north is known
- Angle of difference is recorded at bottom of map
Magnetic bearing
- MB = true bearing + magnetic declination
Grid referencing
Alphanumeric grid:
- May be placed on topographic map to assist
with location of points and places
- Letter before number
Grid reference:
- In SA, all places are South of the equator and
East of greenwich meridian
- Always written in * (degrees) ‘ (minutes) “
(seconds)
- Always written as __*__’__” S __*__’__” E
NB: read latitude reference first (south) (going down) then read longitude
reference (east) (across)
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