Topic 5: Map Reading And Interpretation - Geography Form 3

Topic 5: Map Reading And Interpretation – Geography Form 3

Geography Notes Form Three (3) - All Topics, Map Reading And Interpretation 2 Topic 5: Map Reading And Interpretation - Geography Form 3, Map Reading And Interpretation, Topic 2: Forces That Affect The Structure Of The Earth - Geography Form 3, Topic 7: Application Of Statistics - Geography Form 3, Topic 6: Photograph Reading And Interpretation - Geography Form 3, Topic 4: Elementary Surveying - Geography Form 3, Topic 3: Soil - Geography Form 3, Topic 1: Structure Of The Earth - Geography Form 3

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Map Reading And Interpretation

Map is a scaled representation of a part of the earth or whole of the earth’s surface on a flat surface such as sheet of paper, wall, piece of wood or plastic etc. or 

It is a drawing which represents physical features.

Map interpretation is the process of examining a given topographical map of an area represented for the purpose of identifying the geographical information of an area.

It has two basic process;

-Map reading

-Map analysis.

Map reading -is the process of examining the given topographical map,conventional symbols and signs.
Map analysis -is the process of relating the identified information on the map with other geographical information which are not direct shown on the map.

TYPES OF MAPS

According to functions;

1)    Topographical maps

Are maps which show physical features which are natural features e.g. mountains, valleys, hills etc and man made features e.g. bridges, ponds, roads, settlements etc

2)     Statistical maps

Are maps which show the distribution of things in quantitative manner e.g. distribution of rainfall, temperature, crops etc.. Examples of statistical maps are dot maps, choroploth maps, Isoline maps etc

According to Scale size;

1)     Large scale maps

Are those maps drawn to large scale size e.g. 1:10000

These maps gives a larger representation of small area, they are also more detailed (shows a lot of information). They represent areas like cities, towns and villages.

2)     Medium scale maps

Are those maps drawn to medium scale size e.g. 1:100000

They show a moderate amount of details. They represent areas like districts, regions and countries.

3)     Small scale maps

Are those maps drawn to small scale size e.g. 1:1000000

They give a small presentation of a large area; they show little content (little information)

They represent areas like continents and the world.

IMPORTANCE OF MAP READING

 i)   They provide basis for description of geographical phenomenon

ii)   They are useful for traveling purpose i.e. they guide people to reach their destination

iii)  Maps are useful for storage of geographical information

iv)They are important for field studies

v)  They are important for land use planning

vi)  They are useful for military purposes e.g. during wars.

BASIC SKILLS OF MAP READING/ESSENTIAL ELEMENTS OF A MAP

The basic skills required in understanding how to read a map include;

  1. Title
  2. Scale
  3. Key
  4. Indication of the north direction
  5. Margin/Boundary
  6. Date of compilation

1.Tittle

Tittle gives the name of the country and the area where mapped. It helps the map reader to know what the map is all about. The heading is usually printed in bold capital used on the map

2.Scale

Scale is a ratio between the distance on the map and actual distance on the ground. It is used to find actual distance and areas on the ground. On topographical maps scales are given in form of ratio or lines

3.Key/ legend

Key is a feature which explains the signs and symbols which are used on the map. Not all symbols which are used in the key are applicable to the particular map but all signs and symbols applied on the map are shown on the key.

Definition of terms which should be added on others terms under the tittle “Basic skills of map reading/Essential elements of a map” are ” margins/Bounder

4.Indication of north direction

It gives an idea about the orientation of the map especially in identifying where the north direction is.

5.Margin/Boundary

A frame which borders the map. This guide and limit the map user in reading and interpreting the map. The aim of the margin is to enclose the area covered by the map

6. Date of compilation

Gives the publisher name and when the map was published .This date is important because physical and human settlements features changes with time but the map drawn representing the land does not. For instance between 1960 and 2007 Dar es salaam has changed in many ways.

FROM MAP INTERPRETATION THE FOLLOWING GEOGRAPHICAL INFORMATION CAN BE DESCRIBED

A.DRAINAGE

B.ROCK TYPE/STRUCTURE

C.RELIEF

D. CLIMATE

E.HUMAN ACTIVITIES

F.POPULATION DISTRIBUTION AND SETTLEMENTS.

A. DRAINAGE

Drainage is the plan or layout of the river with its tributaries until it reaches its destination i.e. lake, main river, swamps or an ocean .therefore the concept drainage includes rivers , swamps, lakes, waterfalls ,flood areas

Note:-the common drainage shown on the map is rivers, swamps, lakes and ocean. But expect to see even waterfalls especially on coloured topographical map.

DRAINAGE PATTERNS

-Simply means the network displayed by a river and its tributaries

-Drainage of the river usually posses different network/system depending on the way how tributaries convey to the main river and the general appearance, hence drainage pattern

 

THE FOLLOWING PATTERNS ARE COMMONLY DISPLAYED IN TOPOGRAPHICAL MAPS

 I. DENDRITIC PATTERN

Is a pattern in which its tributaries convey (join) to the main river at an acute angle resembling to the shape of tree trunk and its branches

Note:- Dendritic pattern are common in areas of gentle slope and of uniform(homogeneous)rock hardness. Therefore it can be made from granitic or metamorphic rock

 II.TRELLISED PATTERN

Is the pattern in which its tributaries convey or join to the main river at almost right angle.

 Note:– This type is commonly found in areas with severe cracks or fractures mostly to the rocks with an alternate hard and soft rock. Therefore this is associated with sedimentary rocks.

 III. RADIAL PATTERN

-Is the pattern or layout in which its tributaries flow outward from the center.(summit) or at the peaks of mountains

OR

-is a pattern that resemble a spoken ring of bicycles where stream flow out in every direction from the center.

 

-Therefore radial drainage pattern is commonly associated with volcanic mountains /region composed of granitic rock or igneous rock

 

 

IV. CENTRIPETAL DRAINAGE PATTERN

-this is the pattern in which almost all streams are following from all direction converging to the center can be to the swamp, lake or depression.

OR

-Is opposite to radial as in this type the streams flow toward a common depression center

Note:-The determinant factor of stream flow is a slope .Therefore the drainage pattern can be associated with sedimentary rock.

 

V. RECTANGULAR PATTERN /DRAINAGE.
-Is a pattern which resemble trellised, but it has tributaries joining the main river at a right angle. The pattern is common in areas which are faulted.
-Therefore can be found along sedimentary rocks/granitic rock or any faulted rock.

 

 

VI. BRAIDED PATTERN

-Is the pattern in which its distributaries tend to split into several channels which rejoin and split again .The Congo River has braided channels between Lisala and river Ubangi.

VII. ANNULAR PATTERN.

-Is the pattern with series of streams flowing on flanks or around the dissected dome, depression or crater. Where there are an alternate band of soft and hard rocks.

Note:-This type is not so common, but is found around Lake Bosumtwi in Ghana .Is commonly found in areas affected by back tilting.

B . ROCK TYPE/STRUCTURE

-surface rock on the topographical maps is not directly indicated .They some clues are needed in order to identify rock type and structure of the mapped area.

TYPES OF ROCK IN RELATION TO PHYSICAL FEATURES:-

  •  LAND FORMS
  • VEGETATION
  • NATURE OF THE ROCK

LAND FORMS

-Land forms shown on the topographical maps help on interpretation of rock type
e.g. The presence of volcanic land form such a ;crater, caldera, name of the volcanic mountains suggest the presence of igneous rock.
The presence of erosion and depositional features such as; depression, sand dunes, coral reef suggest the presence of sedimentary rock.
 -Flood plain suggest sedimentary rock
-The presence of highland with steep slope indicated that rock are hard and resistance to the erosion .Hence such hard rock can be granite quartzite and gabbros
 -presence of gentle slope, indicate soft rock e.g. sedimentary rock
 -Flood plains suggest sedimentary rock

VEGETATION

-thick forest suggests the presence of igneous rock.
-poor vegetation cover suggests the presence of sedimentary rocks or metamorphic rock.

NATURE OF THE ROCK

Absence of streams indicates that the rocks are permeable. Thus this depict that the rock is soft which can either be sedimentary, limestone or sandstone.
presence of many streams on surface, indicate that the rock are impermeable such as igneous or granitic rock.

GENERAL INTERPRETATION

  •  Read the contour and the conventional symbols or signs on the map to identify types of  relief. Can either be highland relief with lower arts or lowland relief.
  • Describe the relief with associated land forms.
  • Note:-When you determine types of relief first look on the units (V.I) whether the unit is in meters or feet. If units are in feet take the highest value the convent into meter finally determine type of relief (1m=3.3ft)

CLIMATE
-Climate is the average weather condition experience in a given area over a long period of time not les than 30 years.
-Topographical maps may be used to identify the climate of given mapped area.
-The following clue may be employed to identify or depict the type of climate on a given area

 LATITUDE

  •  0-5N/S of the equatorial imply wet-hot climate particularly EQUATORIAL CLIMATE
  • 5-15N/S of the equator may suggest TROPICAL CLIMATE with seasonal rainfall.
  • 15-30N.S of the equator imply SEMI-DESERT
  •  30-40 N/S IMPLIES DESERT CLIMATE or MEDITERRANEAN CLIMATE

 ALTITUDE

-Look on the contour height on mapped area. If the area experience high rainfall and implies. MOUNTANEOUS CLIMATE.

WATER BODIES
Presence of salt lake
-waterhole (wh)
-bore hole (bh)
-seasonal swamps

ALL these implies semi-arid climate

 

Presence of many streams in relation to the altitude indicates area that receives heavy rainfall.

VEGETATION

Is the total plant cover i.e. vegetation & crops

Vegetation and crops area also good guide on identifying type of climate.

  •  Vegetation can be Natural or artificial (planted tree)Therefore:-
  • -presence of dense forest(tall trees)and bamboo suggest wet climate(equatorial climate or modified equatorial climate).
  • -presence of scattered woodland vegetation suggest moderate rainfall (tropical climate)
  • -presence of scrub/shrubs(thorn forest )and thicket(closely set tree)indicate semi-desert or desert

CROPS

  • Crops also help to depict the type of climate because crops are grown depending on the climatic condition that favours the growth of crop. Therefore
  • The presence of coffee tea pyrethrum rubber and cocoa imply/suggest heavy rainfall i.e. WET-COOL CLIMATE (Tropical highland)
  • Presence of sugar cane sisal cotton I n the absence of irrigation suggest semi-Arid or dry climate. Note (sometimes range from tropical to semi arid with consideration of other factors)
  • The presence of palm tree indicate Wet-warm climate
  • Presence of millet and sorghum imply semi-Desert

Note: On identifying the climate of a given area one is advised to relay on more than one evidence

E. ECONOMIC ACTIVITIES /HUMAN ACTIVITIES

-Topographical map may contain information o economic activities undertaking usually the following are shown on topo maps.

a) ECONOMIC ACTIVITIES

i) Agriculture: – look on the presence of;

  • Rural settlement in absence of other activities
  • scattered cultivation
  • storage houses/center
  • plantation or estate (indicate large scale agr)
  • industry such as Ginneres, Hulleries and Decotecator

seldom symbols or signs are used e.g. S-sisal, CC-coffee, Su-sugarcane

ii) Pastoralism:-look on the presence of;

  • cattle market-cattle dips
  • veterinary installation (Vet. Office)/center
  •  Creamers (lace where milk, cream butter and cheese are processed
  • Scattered vegetation or dominated by scrub/shrubs)
  • Bore holes (Bore holes (BH) or water hole (wh)

iii)mining:-look on the presence of;

  • symbols of PIC () and shovel (
  • salt work
  • quarrying
  • Roasting
  • Sign Tin-TN, Iron-Fe.

iv) Fishing:-look on the presence of;

  •  water bodies such as lakes, seasonal swamps, rivers, dams, ocean. These should be surrounded by settlement.

v) Trade and transportation;-look on the presence of ;

  •  Road, railway, towns and market

vi) Lumbering;-look on the presence of;

  • forest with track-roads ending on their edges.
  • Saw-mill
  • Sao hill forest
  • -Note: thicket, scrubs/shrubs and bamboo trees cannot be exploited as a timber.

Vii) Tourism :-look on the presence of;

  • National parks
  • Game reserve
  • Recreational centre’s  e.g. museum, archives beaches etc
  • Landscape e.g. crater depression etc.

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SETTLEMENT

Is a layout of dwelling in the habitable area where people live and conduct their social and economic activities by interacting with the prevailing environment.
There are two types of settlements which commonly than on the topographic of a map and these includes, rural and urban settlement.

URBAN SETTLEMENT

Is commonly found I areas of the following nature

  •  District administrative centers
  • Regional administrative centers
  • Capital city of a country

RURAL SETTLEMENT

Is an area where the majority of people approximately to cover 80% engage in agriculture

SETTLEMENT PATTERNS.

The signs showing settlements on topographical maps are observed to have varied arrangement. The most common pattern include the following

i) Dispersed pattern

It is alternatively called scattered settlement pattern .The houses are widely spaced one to another