Contours are imag- inary lines that join points of equal elevation on the surface of the land above or below a reference surface, such as mean sea level. Contours make it possible to measure the height of mountains, depths of the ocean bottom, and steep- ness of slopes. A topographic map shows more than contours.
What do contours on maps indicate?
A topographic map illustrates the topography, or the shape of the land, at the surface of the Earth. The topography is represented by contour lines, which are imaginary lines. Every point on a particular contour line is at the same elevation. These lines are generally relative to mean sea level.
What is the purpose of the contour lines?
The purpose of contour lines is to represent the tridimensional shape of the terrestrial surface on a bidimensional map. Contour lines are the intersection of an horizontal plane parallel to the reference level and the topographical surface to describe.
How do you read contours on a map?
How To Read Contour Lines
- 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.
- Supplementary lines appear as dotted lines, indicating flatter terrain.
How do you describe a contour plot?
A contour plot is a graphical technique for representing a 3-dimensional surface by plotting constant z slices, called contours, on a 2-dimensional format. That is, given a value for z, lines are drawn for connecting the (x,y) coordinates where that z value occurs.
How do contours work?
Contour lines connect points that share the same elevation: Where they’re close together (they never intersect), elevation is changing rapidly in short distance and the terrain is steep. Where contour lines are wide apart, elevation is changing slowly, indicating a gentle slope.
What are the 3 contour lines on a map?
Contour lines are of three different kinds. They are the Index lines, Intermediate lines and the Supplementary lines.
How do contour lines indicate a stream?
As a rule of thumb, the V-shaped contour is pointing upstream (the opposite direction from the flow of a stream or river). The “V” shape contours indicate streams and drainage. As you can see, the “V” points uphill to a higher elevation. 3
What is shown with the help of contour lines on map answer?
Contour lines show elevation and the shape of the terrain. They’re useful because they illustrate the shape of the land surface — its topography — on the map.