Question

Which method is used to show the distribution of altitude, temperature, rainfall etc in a map?
A. Choropleth method
B. Isopleth method
C. Dot method
D. Chorochromatic maps

Answer 1

Hint: The given options all are different methods used in thematic maps, but each are used to show very different aspects. An easy clue to consider is that altitude, rainfall, temperature etc. are shown in topographic maps using contour lines. Another aspect to easily find the answer is to consider the names. ‘Choro’ is the Greek word meaning regions, ‘Chroma’ means colours, and ‘Iso’ means similar or same.

Complete answer:
There are so many types of maps that it is difficult to classify them precisely. Generally, they are broadly divided into two types, general and thematic maps. The General maps show the location of various geographic features and phenomena.

Thematic maps show the variation of a single phenomenon emphasizing the pattern of the distribution. Choropleth, isopleth, dot and chorochromatic methods are all different ways that thematic maps show the various details. The methods are different depending on which details are shown. Let us now see which method is used for which details-

A. Choropleth method uses graduated gray tones or colors to show an aggregate summary of any geographical feature within a given area, such as population density or per-capita income. So, this is not the correct answer.

B. Isopleth method uses lines to show the places where elevation, temperature, rainfall, or some other similar qualities are the same. These lines are of various kinds connecting places with the same altitude, pressure and precipitation rate. Topographic maps use the isopleth method. This is the correct answer.

C. Dot method is the process where dots are used to show mass scattered events or features. The places of the events or the locations of the features are marked out in the map using dots. Thus, it is not the correct answer.

D. Chorochromatic maps are maps that use different colours to show various kinds of divisions of a given area. The divisions may be based on physical features, vegetation kinds, climatic zones or even political divisions.

Therefore, the correct answer is Option B.

Note:
i) Isopleth lines are also called contour lines when drawn on Topographical maps. These lines are drawn connecting places which have the same parameters.
ii) Isopleth lines are further divided into isobars (places with equal pressure), isotherm (places with equal temperature) etc.
ii) Dot method is most commonly used when showing locations which are of significance. It is the most used in historical maps.