Special Purpose Maps: maps that emphasize a single idea or a particular kind of information about an area. Examples of special purpose maps can even include maps of Highbanks Metro Park, the Olentangy bike trail, the path of killer bees, even the map from National Treasure. Your Task: climate maps.

Topographic maps

Special purpose maps frequently use images and keys for identification. Physical maps are not used to display elevations or the Earth’s features.

There are 3 kinds of contour lines you’ll see on a map: intermediate, index, and supplementary.

• Index lines are the thickest contour lines and are usually labeled with a number at one point along the line.
• Intermediate lines are the thinner, more common, lines between the index lines.

Whenever you’re in a remote or unfamiliar area, a topographic map and compass are a must. Topographic maps are created from aerial photographs and reveal the contours of the land, including hills, ridges, and valleys, as well as lakes, rivers, creeks, trails, and roads. Contour lines show the elevation of the ground.

You can figure out the elevation of any point by finding the nearest labeled line, counting the number of lines above or below it, multiplying by the contour interval, and adding or subtracting the result from the nearest marked contour line. The more closely spaced the contour lines, the steeper the slope.

An easy-to-remember equation for finding change in elevation as a decimal is “rise over run,” meaning the rise (the change in vertical distance) divided by the run (the change in horizontal distance). As an example, let’s say the rise is 2 and the run is 6. So, you’d take 2 over 6 (or 2/6) to get .

To determine the difference in elevation between two points, determine the elevation at each point and then calculate the difference. Record your answer in feet. In the example below, point A is at 1220 ft. and point B is at 1800 ft.

The elevation difference between two adjacent contour lines is called the contour interval (CI). Usually the contour interval is noted on the map legend. In most topographic maps every 5th contour line is drawn in bold print or wider than other contours. Such lines are called index contour lines.

The difference in elevation between points is called the rise. The distance between the points is called the run. Thus, percent slope equals (rise / run) x 100.

Rule 1 – every point of a contour line has the same elevation. Rule 2 – contour lines separate uphill from downhill. Rule 3 – contour lines do not touch or cross each other except at a cliff. Rule 4 – every 5th contour line is darker in color.

Contour lines can never cross one another. Each line represents a separate elevation, and you can’t have two different elevations at the same point. The closer contour lines are to one another, the steeper the slope is in the real world.

Contour line, a line on a map representing an imaginary line on the land surface, all points of which are at the same elevation above a datum plane, usually mean sea level. Numbers on the lines give the height in feet. (Sea level is zero.) Lines drawn closely together indicate that a slope is steep.

Uses of the Contour Lines

• To estimate the water storage capacity, back water limit and max .
• Volume of the proposed excavation wok,
• To decide whether certain location is visible from another location,
• To decide exact line of railway or road way haing safe slope,
• To determine the ground water level from contours of ground water.

Earth’s surface has many different kinds of landforms that vary widely in height and elevation. Contour maps show the elevations of these surface features, which allows you to look at a two-dimensional map to visualize the Earth in three dimensions.