THE GEOGRAPHER’S TOOLS 18 The Geographer’s Tools HUMAN PERSPECTIVE. At noon on a sunny midsummer day, sometime, around 255 B.C., Eratosthenes drove a stake into the ground at the mouth of the Nile River in Alexandria, Egypt. He then noted the angle of the shadow cast by the stake. Meanwhile at Syene (modern-day Aswan, Egypt), another person drove a stake into the ground— but it cast no shadow. Using the angle of the first shadow and the distance between Syene and Alexandria, Eratosthenes calculated the circumference of the earth. By today’s measurements, he was off by about 15 percent, but he was remarkably accurate considering the simple tools he used. Eratosthenes was one of the earliest geographers to use tools and critical thinking to measure and describe the earth. (Arreola, Deal, Petersen, & Sanders, 2003) Geographers, in their quest to fully comprehend the dynamics of the earth’s surface, answer the basic question for each of the five themes of geography (see previous chapter). To do this, first, geographers collect information or data, perhaps, by conducting a census about a target population, or use data collected by computers and satellites to come up with images (aerial photographs and computer-generated graphics) of sections of the earth’s surface. Second, geographers analyze the information they gathered by looking for spatial patterns and the possible causes and consequences of such patterns. And third, they display information for other Chapter 3 A [Source: Creationist.blogspot.com, 2008] LESSON OBJECTIVES 1. Explain the advantages, functions, and types of maps. 2. Read maps appropriately by using the parts of a map. 3. Identify the time of selected locations using a time zone map. 4. Explain how GIS and GPS help geographers do their work. 5. Explain how models are used in the study of geographic places. 6. Discuss how geographers gather data through fieldwork.
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T H E G E O G R A P H E R ’ S T O O L S
18
The Geographer’s Tools
HUMAN PERSPECTIVE. At noon on a sunny midsummer day, sometime, around 255
B.C., Eratosthenes drove a stake into the ground at the mouth of the Nile River in
Alexandria, Egypt. He then noted the angle of the shadow cast by the stake. Meanwhile
at Syene (modern-day Aswan, Egypt), another person drove a stake into the ground—
but it cast no shadow. Using the angle of the first shadow and the distance between Syene and
Alexandria, Eratosthenes calculated the circumference of the earth. By today’s measurements,
he was off by about 15 percent, but he was remarkably accurate considering the simple tools he
used. Eratosthenes was one of the earliest geographers to use tools and critical thinking to
measure and describe the earth. (Arreola, Deal, Petersen, & Sanders, 2003)
Geographers, in their quest to fully comprehend the dynamics of the earth’s surface,
answer the basic question for each of the five themes of geography (see previous chapter). To do
this, first, geographers collect information or data, perhaps, by conducting a census about a
target population, or use data collected by computers and satellites to come up with images
(aerial photographs and computer-generated graphics) of sections of the earth’s surface. Second,
geographers analyze the information they gathered by looking for spatial patterns and the
possible causes and consequences of such patterns. And third, they display information for other
Chapter
3
A [Source: Creationist.blogspot.com, 2008]
LESSON OBJECTIVES 1. Explain the advantages, functions, and types of maps. 2. Read maps appropriately by using the parts of a map. 3. Identify the time of selected locations using a time zone map. 4. Explain how GIS and GPS help geographers do their work. 5. Explain how models are used in the study of geographic places. 6. Discuss how geographers gather data through fieldwork.
T H E G E O G R A P H E R ’ S T O O L S
19
people to see and learn from in the form of maps, globes, diagrams, tables and graphs
(Williams, 2000).
GLOBES & MAPS (Williams, 2000). Globes are three-dimensional models of the earth.
When using the globe, consider the following pluses and minuses.
Advantages: “(1) most accurately represents the shape of the earth—shaped like a sphere; (2)
most accurately represents shapes of landmasses and bodies of water; (3) most accurately
represents parallels and meridians; (4) most accurately represents direction; and, (5) most
accurately represents distance—best tool to show the shortest distance between two places”.
Disadvantages: “(1) often not practical to use because it is expensive, big and bulky, and you
can view only one-half of a globe at a time; and (2) cannot show detailed features of an area”
\
Maps are flat representations of the earth. They are the product of cartography (the art
and science of making maps). These maps are collected in books that are called atlases, which
present details of places, countries, and continents. Just like the globe, the map has its
advantages and disadvantages:
Advantages. “(1) easier to use because it is easy to carry around—can be rolled or folded up,
provide an easy to use reference when collected into an atlas—collection of maps and related
material; (2) can show the earth’s entire surface or just a small part; (3) can show more detail;
and, (4) can present info about a wide range of topics—physical and cultural features”.
Disadvantage. “All maps have distortions (inaccuracies) because it is impossible to represent a
three-dimensional object like the earth accurately on flat maps. They do not all show areas of
the world in exactly the same way. This occurs because of the difficulty of showing the earth's
spherical (curved) surface on a flat map. Cartographers can take the information from a globe
and flatten the surface of the earth. They use different map projections—ways of showing the
round earth on a flat surface. However size, shape, and distance are distorted when curves
become straight lines.
The Globe’s latitudes (parallels) and longitudes (meridians)
T H E G E O G R A P H E R ’ S T O O L S
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Uses of map. Professor Ulrich Freitag (1993) as quoted by Carter (undated) noted the four
variant functions of maps:
1. The cognitive function encompasses all processes and operations and all models, which
generate and enhance spatial knowledge. All processes of map analysis, transformations,
generalization, simulations, animations, etc. should be listed here, if possible in a sequence
of operations leading from near-reality models to very abstract models of space.
2. The communication function, which includes demonstration, encompasses all processes
and operations of spatial knowledge transfer from a mapmaker to a user. It may be divided
into several sub-functions according to the extent of transferred knowledge, the level of pre-
knowledge, the form and means of knowledge transfer. Educational communication, mass
media communication, academic communication, administrative communication represents
the dimensions of this function.
As a primary communicative device, a map may have the following uses ((Agno & Juanico,
1987):
a. To show the location of something on the earth either in a relative or absolute sense.
b. To show sizes and shapes of the earth features.
c. To reveal distances and directions between places or points on the earth’s surface.
d. To indicate elevation or slope.
e. To show distribution of physical and cultural features.
f. To visualize differences in places or areas and the patterns they create.
g. To allow inferences from data presented.
h. To show change—migration of people, exchange of goods and services, spread of
factories, etc.
3. The decision support function encompasses all processes and operations which -based on
the evaluation of spatial phenomena - result in spatial decisions and spatial actions.
Examples of these types of functions include navigation, planning, and persuasion.
4. The social function encompasses all processes which result not in spatial, but in social
behavior and actions. One form of this involves the professional mapmaker in relation to
other persons in the mapping process, including the users. Maps can also be seen as tools of
social power, exercised through the access or the denial of access to spatial information,
through copyrights or the monopoly on mapping equipment. Then there is the ability to
consider mapping as a cultural activity.
Map Types and Projections (Ludwig, n.d.)
A. Map Types. Maps can be divided into three main classes, or types. They are:
1. General Reference Maps. General reference maps are multi-purpose maps. Their
objective is to portray the spatial association of diverse geographical phenomena.
Basically, general reference maps show a great deal of information. They are extremely
useful in a variety of situations and they are the most common map type.
T H E G E O G R A P H E R ’ S T O O L S
21
Reference maps pay great attention to accuracy. Positional relationships of the
mapped features are extremely important on this type of map. The location of
roads, rivers, cities and other features are carefully plotted. In order to do this,
they may often show and label rivers and lakes, state and local boundaries. These
maps may also show roads, towns and cities, because we often use this
information as basic ways of orienting ourselves about where specific locations
are on the map. Examples are: Road Maps, Topographic Maps, Country Maps
2. Thematic Maps. Thematic maps are different from general reference maps in that they
focus on one topic or theme. The purpose of a thematic map is to show how this topic
changes or differs from place to place.
A thematic map is a special-purpose map, primarily portraying information on a
single topic or a set of topics. It may feature cultural information, such as
population, or physical information, such as annual rainfall. Examples are:
Census Map, Population Map, Weather Map, Agricultural Product Map
Positional accuracy, which is of the highest importance in reference maps, is less
important for a thematic map. It is more important for the map user to pay a great
deal of attention to what type of data was used to create the map and how the
data was mapped on a thematic map. Questions such as, "What is the source of
the data?", "What is the date the data was collected?", and "How was the data
divided into mappable units?" must be asked by the map user in order to insure
that the message the map is telling is accurate.
3. Charts. Maps designed for navigators are called charts. Simply put, maps are to be
looked at and charts are to be worked on. Routes are plotted, positions are determined,
bearings are marked on charts. Examples of a chart are: Nautical Chart, Aeronautical
Chart
Note: It needs to be emphasized that you can probably identify "pure" general reference
maps, thematic maps and charts, but in many cases maps combine functions. For example
the green printing on a topographic map shows the distribution of forested areas. Therefore
topographic maps, deemed a general reference map, can also be a thematic map showing the
distribution of forest areas in a region. Similarly, a thematic map can show political
boundaries, cities, or rivers so that the map user can easily fix locations of the subject
distribution.
B. Map Projections (EPA, 2017). Mapmakers have tried many ways to compensate for the
distortions that happen when drawing the surface of the earth. They have found many
mathematical techniques to convert and portray features from a spherical surface onto a flat
surface. Such a technique is called a map's projection. Map projections can be of three basic
types, or classes. These are:
T H E G E O G R A P H E R ’ S T O O L S
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1. Conical projection is one in which the grid of hemisphere is transferred onto a tangent
cone and subsequently laid out flat as a map. The meridians of longitude appear as
straight lines and the parallels of latitude appear as parallel arcs.
2. Cylindrical Projection is one in which the geographical grid of the globe is transferred
onto a cylinder which encircles it. The cylinder is then cut and laid out as flat as a map,
assuming a rectangular outline of parallels and meridians, which are at right angles to
each other.
3. Planar/Azimuthal or Zenithal Projection indicates the correct direction of an area from a
designation point on the map. A portion or all of the globe is projected onto a map plane,
tangent to the globe at some point.
Cylindrical Projection of the World
Conical Projection of North America
T H E G E O G R A P H E R ’ S T O O L S
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Reading a Map: Parts of a Map (Agno & Juanico, 1987) The parts of a map, which one
should usually look for in reading modern maps are:
1. TITLE. The title of the map tells briefly what the map is all about, i.e., its subject
matter, which could be the distribution of landforms all over the world or a map of
population densities of the 16 regions of the Philippines. The title aids in cataloging,
documentation and use in subsequent research.
2. LEGEND. The legend or key refers to the explanation of the symbols used in a map for
the physical and cultural features that are indicated.
3. SCALE. The scale is the relationship or ratio between a linear measurement on a map
and its corresponding true distance and compute area. There are three types of scales:
word/verbal scale (“one cm. equals one km.”); fractional (“1: 250, 000”); and
graphic/bar or linear (scale is indicated by means of graduated line)
4. LATITUDES & LONGITUDES. The latitudes and longitudes are the lines drawn by
convention over the earth’s surface in order to indicate direction and the location of an
area. They are parallels and meridians that intersect each other and are together referred
to as MAP GRID.
5. DIRECTION. Direction is indicated by some maps with a north arrow even if these do
not have lines. The north arrow can refer to either to the true (geographic) north or the
magnetic north. The true north is one, which is in complete alignment with the meridian
and points to the geographic North Pole through which the earth’s axis passes. The
magnetic north is one that is aligned with the flows of the magnetic force around a bar
magnet. This is the north indicated by the magnetic compass needle. The north magnetic
pole is located near Viscount Melville Sound north of Canada’s Prince of Wales Island.
Compass Rose. The compass rose shows you the north (N), south (S), east (E),
and west (W) directions on the map (Arreola, Deal, Petersen, & Sanders, 2003).
6. LABELS, SYMBOLS, COLORS. Labels are words or phrases that explain features on
the map. Symbols represent such items as capital cities, economic activities, or natural
resources. Colors represent a variety of information on a map (Arreola, Deal, Petersen,
& Sanders, 2003). Other maps may include the date of publication, publisher and the
cartographer.
Planar/Azimuthal Projection of the world [viewed from the North Pole]
T H E G E O G R A P H E R ’ S T O O L S
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Maps and time zones. Before the late nineteenth century, time keeping was essentially a
local phenomenon. Each town would set their clocks according to the motions of the sun. Noon
was defined as the time when the sun would reach its maximum altitude above the horizon.
Cities and towns would assign a clockmaker to calibrate a town clock to these solar motions.
This town clock would then represent "official" time and the citizens would set their watches
and clocks accordingly.
In 1878, Canadian Sir Sanford Fleming suggested a system of worldwide time zones that
would simplify the keeping of time across the Earth. Fleming proposed that the globe be divided
into 24 time zones, each 15 degrees of longitude in width. Since the world rotates once every 24
hours on its axis and there are 360 degrees of longitude, each hour of Earth rotation represents
15 degrees of longitude.
In 1884, an International Prime Meridian Conference was held in Washington D.C. to adopt
the standardized method of time keeping and it determined the location of the Prime Meridian.
Conference members agreed that the longitude of Greenwich, England would become zero
degrees longitude and they established the 24 time zones relative to the Prime Meridian. It was
also proposed that the measurement of time on the Earth would be made relative to the
astronomical measurements at the Royal Observatory at Greenwich. This time standard was
called Greenwich Mean Time (GMT- former standard world time as measured at Greenwich,
England (location of the Prime Meridian), which was replaced in 1928 with Universal Time
(UT). Universal Time is commonly used to denote solar time.).
NOTE: International Date Line (IDL)—opposite the Prime Meridian, is used in marking
the passage of time or of one day as the earth rotates on its axis.