1.8: Mapping the World

Part 2: Mapping the World

Original text taken from: 1 Dorrell & Henderson

The following is a remixed and adapted version of Chapter 1 Itnroduction to Human Geography by Dorrell and Henderson https://web.ung.edu/media/university-press/human-geography_v2.pdf?t=1700179494361

Mapping the World

Maps are fundamental to the discipline of geography and have been used by humans since before 6,000 B.C. Today’s maps are much more sophisticated, complex, and precise, and are used by many people who employ GPS mapping systems in their vehicles. This technology allows motorists to navigate from place-to-place with relative ease, but the process by which these digital and other maps are created is exceptionally complex. Essentially, a map, which is a flat presentation of a place on Earth, is actually depicting a curved surface. The Earth, which looks like a sphere, is technically an oblate spheroid, which means that the “middle” of the Earth, around the equator, is slightly wider, and the north/south pole axis is slightly shorter, than a perfect sphere. When any curved surface is depicted on a flat surface, that process is known as projection, and many types of map projections exist. A fundamental characteristic of all maps is that they involve projections, and all projections have some sort of distortion inherent in them. The size, shape, distance, and direction of objects are distorted to various degrees on maps. The reason this distortion occurs can be visualized by simply imagining peeling an orange, and trying to flatten the peel on a table. If you drew the continents on that orange before peeling it, the continents would most certainly be distorted when you try to flatten the peel on the table. This analogy does not precisely describe how projections are created; the process is much more involved. However, the underlying principle still applies. An example of distortion is shown on the map of the globe below (Figure 1.2). Note, for example, in this Mercator projection that Greenland appears to be larger than South America, although it is, in fact, much smaller.

Figure | World Map World Map with Mercator Projection. Author | User “Strebe” Source | Wikimedia Commons License | CC BY-SA 3.0

Besides projections, another important characteristic of maps is the scale. The scale of a map is a ratio of the length or distance on the map versus the length or distance on the Earth or ground (actual). The amount of detail shown on a map will vary based on the scale. For example, a map with a scale of 1:100,000 (which means 1 in/cm on the map equals 1,000,000 in/cm on the ground) would show much less detail than a map at a scale of 1:10,000 (Figure 1.3). Besides showing scale as a ratio, it can also be presented as a bar graph or as a verbal statement. Scale can also mean the spatial extent of some kind of phenomena. For example, one could examine migration at the global, national, state, or local scale. By either definition, however, each refers to the level of detail about the place that the geographer is researching. Examining the world from different scales enables different patterns and connections to emerge.

Identifying Locations on a Map

One of the most important pieces of information that maps provide is location. Knowing precisely where a place is in the world is fundamental to geography. While one can define a location simply by using a street address, not all places on Earth have such an address. Therefore, one of the basic ways to pinpoint a location on the Earth is using the geographic grid. The geographic grid is composed of meridians and parallels, which are imaginary lines and arcs crisscrossing the Earth’s surface. Meridians are half circles that connect the north and south poles, and longitude refers to the numbering system for meridians. Parallels are circles that encompass the Earth and are parallel to the equator, and the numbering system for these circles is known as latitude (Figure 1.4). Where meridians and parallels intersect at precise locations (points) on the Earth on the geographic grid, a location can be known by its latitude and longitude.

Figure | Longitude and Latitude The geographic grid comprises meridians and parallels with longitude and latitude. Author | User “Djexplo” and Corey Parson Source | Wikimedia Commons License | CC 0

A few meridians on Earth are of particular importance, one being the Prime Meridian located at 0o longitude, which passes through Greenwich, England. The other important meridian, called the International Date Line, follows roughly along 180 o longitude, and this meridian is on the opposite side of the world from the Prime Meridian (Figure 1.5). When a traveler crosses the International Date Line, the day of the week instantaneously changes. When moving westward, the day moves forward, and when traveling eastward, the date jumps backward one day. Fortunately, the International Date Line is in the middle of the Pacific Ocean, so disruptions to the daily calendar are minimal for most people in the world. Moreover, the International Date Line does not precisely follow the 180 o longitude line, and this accommodation allows countries and territories consisting of islands that straddle 180 o longitude to share the same calendar date.

Figure | Time Zones This world map shows the international date line and global time zones. Author | Central Intelligence Agency Source | Wikimedia Commons License | Public Domain

How do I Describe Where I am?

Defining a location by using the geographic grid is only part of the process of describing a place. Geographers are primarily concerned with two ways of describing a place: site and situation. Site refers to the physical characteristics, such as the topography, vegetative cover, climatic conditions, and the like. Situation, on the other hand, refers to the area surrounding the place, and is sometimes referred to as relative location. In other words, where is this place relative to other places, and how is it connected to its surroundings via transportation networks? New Orleans provides an excellent example of site versus situation. The site of New Orleans is not ideal for a city, as it lies below sea level and is prone to flooding. However, the situation of New Orleans is much better in that New Orleans is connected to a large portion of the Mississippi River’s network of navigable waterways while also being close to the Gulf of Mexico and convenient to coastal traffic. Hence, the situation of New Orleans is why the city has not long since been abandoned, despite catastrophic flooding such as during Hurricane Katrina in 2005. As we examine various places around the world, both site and situation are key considerations in determining the “why” of where a place is located.

Geographic Data Collection & Analysis

In order to analyze and develop regions, describe places, and conduct detailed geographic analysis, two important tools have been developed that are of particular value to geographers. The first is remote sensing, or the acquisition of data about the Earth’s surface from aerial platforms such as satellites, airplanes or drones. Images taken from these airborne machines can provide a wealth of valuable information about both the human and physical characteristics of a place. For example, satellite imagery can depict the extent of human impact on rainforests in the Amazonian rainforest of Brazil (Figure with greens and blues). Imagery can also depict information that humans cannot see with the naked eye, such as the temperature of the Earth’s surface. One example is a thermal infrared image, which can show warm temperatures in red tones and cooler temperatures in blue tones (Figure below in red.).

Figure | Deforestation Deforestation in the state of Rondônia, western Brazil. Author | NASA Source | Earth Observatory License | Public Domain

Figure | Thermal Imaging Thermal imagery of Atlanta, GA. Author | NASA Source | Wikimedia Commons License | Public Domain

Digital imagery like the one in figure directly below this, is in a format that can be entered into Geographic Information Systems (GIS), the second important tool employed by geographers. GIS combines computer hardware and software in a system that stores, analyzes and displays geographic data with a “computer mapping” capability. Geographic data is stored in layers, and these layers of data can be queried in a number of sophisticated ways to analyze some aspect of an area (Figure below). Each data point in a GIS is georeferenced to a precise location on the Earth’s surface (latitude and longitude, for example), and these data points have different attributes corresponding to the data layer they are associated with. Data layers can represent a myriad of characteristics about that data point, such as elevation, soils, the presence of water, per-capita income, ethnicity, etc. Overlaying the data layers can provide incredible insights into the connections between characteristics/ factors in places, such as the connection between per-capita income and ethnicity or the links between soil types and vegetative cover. GIS also has a vast suite of other capabilities such as least-cost path for transportation, line-of-sight perspectives from a particular location, or 3-D models of urban areas. Because of their multifaceted capacity to present geographic information, businesses and government agencies around the world use GIS to answer questions, plan development, chart delivery routes, and even monitor crime and first responder activity (Figure 1.12). It is not surprising that one of the fastest growing job markets is in GIS technology, as GIS jobs exist at the local, state, and national level as well as in many businesses in the private sector. Even the U.S. Census Bureau maintains an extensive GIS database known as Topologically Integrated Geographic Encoding and Referencing (TIGER).

Figure | Data Layers Data layers in a Geographic Information System (GIS). Author | US Government Accountability Office Source | National Geographic License | Public Domain