Everything (Well, Almost) You've Always Wanted to know About Your Land

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MAP BASICS

You don't have to be a trained cartographer to decipher topographic and geologic maps. In fact, you need only a few simple skills . . . most of which you probably learned in your sixthgrade geography class. North, of course, is always at the top of the map as you hold it straight in front of you, with the other directions at the corresponding positions on the sheet: south to the bottom, east to the right, and west to the left.

The scale-which is usually noted in a margintells you how many miles (or feet) are represented by each inch on the map. There's also a legend that explains the symbols, numbers, or color shadings used on the diagram. It's wise, too, to look for the date on which the map was drawn and/or revised . . . since streambeds do shift, and roads and buildings come and go.

In short, all the information you'll need will be right there in print. You'll just have to use your imagination to translate that one-dimensional picture into an image of the actual landscape.

Now that sounds easy, I know, and it will seem to be so . . . until you unfold a topographic map for the first time.

Believe it or not, though, that confusing swirl of lines, blotches, dots, and numbers (which will tend to bewilder you at first) can actually convey a great deal of important information to any future—or present-landowner who knows how to read it.

TOPOGRAPHIC MAPS

A topographic map is no more (or less!) than an accurate and detailed representation of a specific portion of the earth's surface. It indicates streams and springs, lakes, roads and trails, buildings, wooded areas (these are shown in green), and—most important of all—the actual contour of the land. With its distinctive curving lines, the "topo" map (as it's commonly called) manages to produce a three-dimensional picture on a flat surface. To understand this, think of the topographic layout as a view from above . . . looking straight down on a piece of property's peaks, valleys, and slopes. The rise and fall of the landscape is represented by the map's curving lines. (In fact, cartographers commonly draw or update these maps with the help of high-resolution aerial photographs . . . but only do so after making or consulting a detailed ground survey.)

The topographic contour lines portray elevation intervals of 10 or 20 feet, so the map reader can figure not only how high the land is, but also how gradually-or steeply-it slopes. For example, in Fig. 1 (a typical ridge) the wide spacing of the lines on the south and southwest faces of the land mass indicate a gentle downward incline. The contour lines on the cast side, however, are so close together that the map reader can deduce the presence of a cliff . . . and Fig. 2, which is a ground-level view of the same piece of land, proves the point.

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