Topography Maps

Topographic Map

A special type of map that uses contour lines to show landforms.

Verbal Scale Example

1 inch = 2000 feet (1" = 2000’).

Map Scale

An indicator of the size of the map area and features, often shown as a ratio, bar, or verbal scale

Ratio Scale Example

1:24,000 this means 1 unit on the map equals 24,000 units in real life.

Bar Scale

A graphical representation of distance using a bar with labeled intervals.

Contour Line

An imaginary line on a topographic map that connects points of equal elevation.

Contour Interval

The difference in elevation between adjacent contour lines.

Mean Sea Level (MSL)

The reference point for elevation on topographic maps.

Relief

The difference in elevation between high and low points in an area.

High Relief

Great elevation differences, such as between a mountain and a valley.

Low Relief

Little elevation change over a large area, such as a plain.

Gradient

Relief divided by distance.

Topographic Profile

A cross

Vertical Exaggeration (VE)

Vertical scale divided by horizontal scale, used to emphasize relief in a profile.

Contour Line Rules

1) Cannot intersect, bifurcate, or cross other lines

2) Are closed loops

3) Cannot intersect a level body of standing water

4) Run parallel to adjacent lines

5) Closely spaced, steep slopes. Widely spaced, gentle slopes.

6) Merge on a vertical slope

7) V shape pointing uphill when crossing a stream valley

8)Closed loops around hills or depressions. Hachured lines mean closed depression