Topographic Map Rules

Topographic maps tell you more than elevation.
••• gorges pointe de musandam image by Emir OBOLAN from

Contour maps provide an easy method of depicting the changes in elevation across an area. They let anyone visualize the shape of a landscape without having to fly overhead. Knowing a few simple rules can increase the amount of information gathered from any topographic map and help you interpret the features of any landscape.

Contour Lines Never Cross

Lines indicating elevation should never intersect on a topographic map, because each line represents a different elevation, so it is impossible to have two elevations at the same location.

Measuring Steepness

The closer together contour lines are, the steeper the slope of the hill. If the spacing between lines stays the same then the slope is constant. If the distance between lines changes, then the slope also changes.

Stream Flow Direction

When contour lines cross valleys, they will form a V shape. The V always points uphill. You can use this to determine which way water will flow across an area depicted on a topographic map.

Contours Close

Contour lines form irregular circles and do not end at a random point. Every contour line can be followed around back to where it started, although this may be beyond your map's borders.

Concentric Circles

Concentric circles represent hilltops and depressions. A depression or hollow where the elevation drops and is surrounded by higher terrain will be marked by closed irregular contours with hash marks on the line. The markings point inward from the edge and indicate that the area inside is lower. These areas will appear to have a crater or bowl shape.

Elevation Between Lines

The elevation between two contour lines is never higher than the value of the higher contour line. For example, between a contour line marking 500 feet and another marking 600 feet, there could not be a point where the elevation is 650 feet without additional contour lines.

Related Articles

How to Read Topographic Maps
What Is the Importance of Topographic Maps?
How to Read Elevation Maps
Landforms Near Chicago
How to Calculate Contour Intervals
Weather Conditions After a Cold Front
How To Calculate The Area of an Irregular Shape
How to Calculate Gradients on a Topographic Map
Does Barometric Pressure Rise or Fall When It Rains?
How to Make a 3D Cone Shape
The Relationship Between Pressure Gradient & Wind Speed
What Is the Difference Between AGL & MSL?
Seagull Behaviors In Earthquakes and Changes in Weather
Topography Types
How to Build a Model of a Mini-Basketball Court
How to Calculate Channel Slope
How to Find the Angle of a Curve
How to Calculate Runway Slope
How to Calculate the Slope of Regression Line
The Three Types of Weather Fronts