EOSC210 Topography

Required in Constructed Maps Are:

LOTS:

• Legend

• Orientation

• Title

• Scale

Verbal Scale

1cm = 100m

Fractional Scale

1/10,000

Graphical Scale

Contour Lines

lines of equal elevation represent the shape of the land surface

Contour Interval

The elevation difference between lines

Topographic Relief

Difference in elevation present within the map area

High Relief

rapid changes in elevation over short distances

Low Relief

small changes over long distances

Stream Gradient

(vertical elevation change)/(horizontal distance)

12 Rules for Constructing Topographic Map

1. Every point on a contour line is the same elevation (i.e. contour lines

connect points of equal elevation).

2. Contour lines separate points of higher (uphill) elevations from points of

lower (downhill) elevation.

3. Contour lines fall in simple multiples of the contour interval with zero

representing mean sea level.

4. Contour lines never intersect or cross, except in the case of

overhanging cliffs.They coincide only on vertical cliffs.

5. Contour lines always close but the closure may take place

outside the map boundary.

6. Contour lines never split.

7. The closer the contour lines, the steeper the slope.

8. Evenly spaced contour lines represent a uniform slope.

9. Closed contour lines represent a hill or a hollow

depression.

10. Depression contour lines have sometimes hachure

marks on the downhill side, always close and represent a

closed depression.

11. Contour lines “V” in an upstream direction and

cross the stream at the sharp point of the “V”.

12. Whenever vertical direction changes on the map

(crossing the top of a hill or the bottom of a valley)

the same contour line is crossed twice.

*bold/underlined are key rules to remember

Topographic Profiles

• A cross-section constructed along a line of particular interest on

the map to illustrate the relief displayed on the map.

• The profile can be considered as a graph on which the elevation

is plotted against the horizontal distances.

• Orientation of the profile must be labeled.

• Example- A-B (West- East)

Vertical Exaggeration

VE = (Vertical Scale)/(Horizontal Scale)