Jerry T. Mitchell - Geography For Dummies

IN THIS CHAPTER

Knowing what a map is showing

Measuring distance and size

Taking a look at graphics

Using symbols to depict reality

Finding ways to gather information

Harnessing new technologies

I collect old maps, particularly ones of places I once lived like Maryland, Pennsylvania, California, and so on. So, I’m a geek, I guess. Before you think of yourself as being too cool, remember that no one made you pick up this book. So, I guess I’m not the only geek out there!

Of those maps, one is my most prized and until I found a copy in a dusty shop in Savannah, Georgia, I had not seen one like it. It’s a map of major world rivers and mountains published in Gray’s Atlas in 1874. But it isn’t laid out like a traditional map. Each major river is positioned side by side from longest to shortest, and each major mountain is in a row by continent from shortest to tallest. I find the comparisons and different layout fascinating and spatially pleasing for some reason only geeks like you and me can understand. A neat added feature in one corner is a smudged fingerprint. I love the idea of someone like me — or you — exploring physical Earth space with this map nearly 150 years ago.

Over the years, and much to my relief, I have met numerous other geography geeks (geography teachers and students among them) who, however meekly, admitted to similar map affections. Indeed, such behavior turns out to be perfectly normal for people who, whether or not they know it, have a yearning for geography. No doubt, that is because the map is the most basic geographical tool.

Complementing the previous chapters on Earth’s grid and the properties of projections, this chapter focuses on ways in which maps communicate information and how some of that information is obtained. Basically, this chapter is about map reading and map information for the budding geographer. Therefore, if you are, in fact, one of those people who can stare at maps for hours, then you can probably skip this chapter. But if maps confuse you or seem overwhelming, or if you have never been taught the fundamentals of maps and map reading, then this chapter is for you. While you probably won’t master all there is to know, you can familiarize yourself with enough fundamentals so that you get the message of maps.

The basic function of maps is to show how particular phenomena are distributed over all or part of the world. Cartographers (mapmakers) communicate these and other kinds of information in part by incorporating into their maps a standard set of elements whose purpose is to help the map-reader get the message.

An easy way to remember these elements is with the acronym TALDOGS:

Title: The title conveys the subject of the map and is the first thing a map-reader should look for. Ideally, its wording is simple and accurate. If the title confuses you, then that is probably more of a comment on the cartographer’s communication skills than your intelligence quotient.

Author: Knowing who made the map might say something about the map’s credibility. Are you more likely to trust a map made by the National Geographic Society or one you found online created by joebubba12@email.com (that’s right, we just made that email address up, so no writing in, Joe!)?

Legend: Maps commonly convey information with the aid of symbols whose meanings may be uncertain. Thus, the cartographer always provides a legend (or key ) that contains and defines the symbols found on the map.

Date: Every map in print is out of date once printed — the world changes that fast. Newer digital mapping technologies are making this a problem of the past as we can update spatial data more quickly. However, knowing when data is collected can help us in making spatial and temporal comparisons.

Orientation: Orientation is the alignment of the map with respect to cardinal directions : which way are north, south, east and west? The standard rule is that north is towards the top of the map, but not every layperson knows the rule and not every map follows it. Accordingly, many maps include a direction indicator, minimally a north-pointing arrow.

Grid: Many maps contain a couple of labeled grid lines of latitude and longitude (see Chapter 3) in order to convey the global context of the mapped area. If the cartographer has reason to believe that the map reader is intimately familiar with the mapped area, or if previous maps have indicated the global context of the mapped area, then grid lines may be omitted.

Scale: Scale (described more fully in the following section) provides information about the actual size of the area shown on the map. Typically, this is achieved with a small ruler-like entry on a map that equates distance in miles and/or kilometers with measurement in inches and/or centimeters.

Scale is the relationship between a distance as measured on a map and the corresponding actual distance on Earth’s surface. Calculating distance between locations and comparing the size of areas are two of the more important functions of maps.

The scale of a map may be stated in three rather different ways, described in the following sections. Figure 5-1 shows you what the three ways look like. Some maps include just one of them. Others include two, and still others all three. Perhaps the most important thing to remember is that every map has a single scale, but a cartographer has three ways to tell you what it is. If, therefore, a single map contains two or three of the scale-types, then each is saying the same thing, albeit in a different way.

(© John Wiley & Sons Inc.)

FIGURE 5-1:Three ways to indicate the scale of a map.

A scale bar looks like a miniature ruler. But whereas the ruler you use may show inches and millimeters, the one on the map shows miles or kilometers, (as shown in Figure 5-1). The principal virtue of the bar graph is that it provides a clear visual reference to the size of the area portrayed on the map. For actual measurement, however, it may be a bit unwieldy because you can’t pick it up like you can a real ruler.