Maps and map interpretation

What is a map?

Map is a scaled conventional representation of the whole or any of the earth’s surface on a flat body. Or

A scaled conventional visual representation usually on a plane surface of a region of the earth.

Flat body into which maps, established include, a piece of paper , blackboard, wall, wood, cloth and others of the same consideration.

Maps are the most valuable and powerful equipments in Geography as used for providing geographical details of varied areas represented. They are geographical details of varied areas represented. They are also used for storing the geographical details of areas represented. Some of the geographical facts which can to depicted by maps about areas represented include; climate, relief, human activities, soils, drainage system, vegetation, settlement, settlements, communication and others of similar consideration. It is thus; maps are so useful for making geographical facts description about the respective areas represented. Other useful tools apart from maps which also enhance geographical studies; graphs, globes, globes, ground photographs, aerial photographs and the satellite images.

CATEGORIES OF MAPS

Maps used in geographical studies are extremely varied and belong to different forms. They are classified by considering the following categorizing factors.

a) Their varied functions

b) Scale size used

c) The degree of accuracy

Maps according to functions

Classification by function, it is taken into consideration of what a particular map shows. Maps portray varied geographical facts and thus are of different functions depending on what shown. With respect to this, map are broadly categorized into four and include the following.

i. Topographical maps

ii. hematic maps

iii. Statistical maps

iv. Cadastral maps

TOPOGRAPHICAL MAPS.

The maps are named with the world ‘topography‘ which has been derived from a Greek world of ‘Topos’ The word topos means the actual appearance of a place by its natural and artificial features.

Or

. The map which has been designed to give a general future (description) of the landscape of a very limited part of a country by showing both natural and artificial features.

Or

Map whose principle purpose is to portray and identify the features of the earth’s surface as faithfully as possible with in the limitation imposed by scale.

Topographical maps considerably to their future of function are also known as general maps.

Characteristics of topographical maps

1. Show both natural and artificial features of areas represented.

2. They are drawn on their medium or large scale depending on the size of the area represented.

3. Represent small or limited parts of a country

4. They are more detailed as represents small parts on large scale.

Thematic maps

These are the special maps which concentrate on showing the spatial distribution of a single geographical phenomena among the several of areas represented.

Or

Types of map especially designed to show particular theme connected with specific geographical areas. i.e. they show the distribution of only one geographical fact among the several of a particular region. These can portray physical, social, political, economic, or any other espects of a city, state, region, continent and world at large.

Thematic maps are differently named according to the nature of content (details) of an area represented and include the following:-

Relief maps:- These show the physical appearance of areas represented by giving the major land forms.

Political maps:– They show political boundaries of administrative for regions represented.

Geological maps: The maps concentrate on showing the geological nature for the regions represented.

Soil maps: The ones which show the spartial variation of soil nature for areas represented.

Economic maps: These show the spatial distribution of chiefs crops, animals, industries, minerals and others.

Historical maps: show the distribution of the historical sites.

Statistical maps.

These are the geographical maps which show the distribution of certain geographical phenomena in values of phenomena of interest in geographical studies lie temperature, population density, movement of goods or people and others of related. With the use of statical maps, one can make quantitative analysis of a phenomena for the area shown on the map.

Statistical maps are further differentiated by considering the means used to show the values of distribution on the map face. Owning to the consideration, statistical maps include the following:-

Isopleths maps.

These statistical maps which show the distribution of a certain geographical phenomena in quantitative manner by of lines. The lines are established on a map face to join points with equal amount of distribution with reflection to an actual area on the earth’s represented.

The used lines have special names depending on a nature of phenomena shown on the map.

Isohyets: for rain fall

Isotherms: for temperature

Isobars: for atmospheric pressure

Isohaline: for salinity

Isobaths: for ocean depth

Dot maps.

Such statistical maps designed to show values on spatial distribution of a certain geographical phenomena by means of fixed size dots as inserted on a map face. Each dot on the map carries equal values similarly to others.

Choropleth maps.

These statical maps are designed to show values on the distribution density of a certain geographical phenomena like that of population by means of varied shade texture. The map is established to have a key to interpret the categories of quantitative values represented by the varied shades.

Flow line maps:

These are designed to show the quantitative values on movement of certain geographical phenomena like passengers or goods from one place to another through an established route way of like: a d, railway, water way and others by means of flow lines of varied width. i.e. the amount on movement reflected by the width of the flow lines.

Cadastral maps

They are the maps of large scale which show more Clearly the layout and boundaries of features of a very small size represented. i.e. The maps show precise locations and names of the features of the area represented.

Cadastral maps are mostly designed for ownership purpose. These maps may show the layout of features in a village, part of a town, industrial area, school compound, home steady and others of the same reflection.

Cadastral maps are commonly designed after the boundaries of the features in the area to have been accurately surveyed. The type of survey that concentrates on taking the actual measurements of features boundaries is known as cadastral survey. It is thus the maps are named in basis of the technique used to get details that appear on the map.

Maps according to scale size.

Maps being much smaller in size compared to actual areas represented, are precisely designed up on distances to grounds represented. However the maps size of the ground and amount of details shown, Being drawn up on varied scale size, makes maps appear extremely varied and this becomes another important categorizing factor of maps. It is thus, maps according to scale size categorized into the following types.

i. Large scale maps

ii. Small scale maps

iii. Medium scale maps

Large scale maps.

These are drawn on large size to give larger representation of limited parts of a country like a town or village. These commonly established on large spaces of flat bodies.

Characteristics of large scale maps

1. They are drawn on large scale size e.g. 1:10,000, 1:20,000 etc.

2. The maps give larger representation of areas portrayed.

3. They represent very limited parts of the country

4. They are more detailed.

Small scale maps.

These are the geographical maps drawn on small scale representing larger area size of the earth’s space

of the body.

Characteristics of small scale maps:

1. They are drawn on small scale e.g. 1:1,000,000, 1:10,000,000 etc.

2. The maps give smaller representation of the areas of the earth’s surface.

3. They commonly represent very huge parts of the earth’s surface like a country, continent or the whole of the earth’s surface.

4. The maps are more selective and thus, show less details of represented due to the limitation of map space.

Medium scale maps.

These are the maps drawn on medium scale size to represent parts of the earth’s surface.

Characteristics of the medium scale maps

They are drawn on the medium scale size E.g. 1:100,000,1:25,000,1:150,000 and others of the same consideration.

1. Both the map and ground represented are of medium size.

2. The maps show moderate level of details.

Maps according to degree of accuracy.

Cartographers try to their level best to make maps most accurate in order to reflect the reality of areas portrayed. They employ varied techniques to make maps be of reasonable accuracy, However, with respect to this consideration, some maps are made accurate, while others not accurate and thus: maps differ in the degree of accuracy and this also taken as maps according to the degree of accuracy broadly classified into two types and include:

i. Outline maps

ii. Accurate maps

Outline maps.

These are the simple maps which not accurately designed as drawn not up on scale. They are commonly shown in text books to make simple illustration of the geographical facts. Moreover, they are commonly printed or copied for personal or classroom uses.

Accurate maps.

These are the ones which have been precisely designed as drawn with the use of correct measurements of the area, its features as well as the map itself. i.e. the maps accurately designed with up on scale.

Commonly on the map, the represented area and the features made to have correct size.

Accurate maps are subdivided into two depending up on the technology used o maintain the accuracy.

Surveyed maps.

These are the maps made accurate taken by actual measurements on distance, area represented. Most of the topographical maps correspond to this category.

Project maps

These are the maps which show the accuracy of the earth’s surface curvature (spherical shape) on their faces maintained by the cartographic technique of projection.

USEFULNESS OF MAPS

1. Maps provide good basis for making orderly geographical facts description of regions represented. i.e. The geographical facts of an area such relief, drainage, settlement, communication,vegetation and others easily recognized and described from the topographical map.

2. They provide ideal insight into significant relationship between geographical f variables. I.e. They are considered to establish the relationship between the geographical variables . E.g and soil,relief and vegetation, climate and vegetation etc.

3. In connection to above point, maps are so powerful tools for making spatial analysis of geographical facts for areas represented. i.e. from map , the determinant factors for spatial variation of geographical phenomena detected.

4. They are so potential for field studies.

Maps are useful for traveling purpose. They guide people to reach points of designation·    Maps are useful for locating the position of geographical features .It is achieved by a wide range of methods mostly, grid reference, place naming the use of latitudes and longitudes bearing and distance.

5. Maps make storage of the geographical facts of areas represented. Hence the give insight to the previous appearance of areas.

6. Maps can be used to make quantitative analysis of certain geographical facts like size, distance, gradient, drainage density in response to scale consideration.

7. Maps are used for military purpose. i.e. they used to develop military strategies by providing vital details to military troops.

8. Maps are used in the conduct of a wide range of projects like: population census, land use planning, building design, construction of roads and others of the same reflection.

SET BACKS OF USING MAPS.

1. Maps are convention, and thus do not give the morphology of features represented. Features on maps appear by means of convention signs, symbols and abbreviations.

2. Maps are selective. It is not possible for all details to appear on the map. Hence: with the use of maps in geographical studies, we lack some of the details.

3. The features shown on the maps may not be all maintained on a constant scale. It is thus, uses may get distorted measurements of the features from the map.

4. Maps may provide the outdated details about the respective areas represented. It is automatically set as details in actual areas may change with time while maps once designed remain unchanged. Moreover, it becomes difficult to update the map that has already been designed.

5. The reading and interpretation of maps needs high and perfect skill.

6. Maps are not capable to record and keep instant data

EXERCISE

Qn. Briefly explain any five merits of such topographical map to a map user (NECTA 2000 – The extract map of madukani series 742)

Qn. Outline the strengths and weakness of using topographical maps in geographical studies. Mock –