1. Topographic Maps Definition:
“Topographic maps show the 3-D shape of the landscape by representing equal elevation with lines on a 2-D map”
History:
France – 1789 (first full scale map)
England – 1857 (mapping the Himalayan Mts)
Intro:
Field – a region of space in which there is a MEASUREABLE quantity of a given property at every point
Examples: Temperature, Pressure, Elevation, etc.
The strength of a field varies
The farther away from the source, the weaker the field – increasing distance = less detail and accuracy – shooting a basketball from 5 miles or 1 foot!
Fields can be MAPPED by placing measurements on paper and connecting locations with EQUAL readings with figures called ISOLINES!!!

2. Topographic Maps 5 5 10 10 10 10 15 15 N W E S
Contour Mapping Rules!!
In Earth Science a line representing equal elevation or altitude on a 2-D map is called a CONTOUR LINE or CONTOUR.
They never CROSS – impossible – against the laws of physics and the known universe!!!
They are a complete loop/curves (joins up)
They have gentle curving lines, no sharp corners
Usually end up in parallel patterns
Drawn according to the specific INTERVAL of the map
Whole numbers – no 4.5 or 6.1/2 values
Compass Rose
The compass give us directions North, South, East and West, based on the orientation of the map. 5 5 N
10
10
10 W E
10
15
15 S

3. Topographic Maps
Calculating the interval:
The contour map interval is:
“The vertical distance or difference in elevation between contour lines on the map, a given value and consistent throughout the map”
Index contour line (important elevations):
“A labeled elevation contour line, usually thicker, more pronounced than the others. Occurs for every 4 or 5 contour line”
To calculate the interval of the contour map, find and count how many contour lines between each index. Then, figure out what the interval is based on index difference and how many contour lines between them.
What would be the contour line interval for the above map?

4. Topographic Maps SCALE:
The scale is something that tells you how the distance on the map compares to the distance on the ground.
A map scale usually is given as a fraction or a ratio—1/10,000 or 1:10,000.
These "representative fraction" scales mean that 1 unit of measurement on the map—1 inch or 1 centimeter—represents 10,000 of the same units on the ground.
The fraction or ratio always begins with 1 as the first number, whereas the second number can change. If the second number is small the map would be large scale and vise-versa. This allows the map size and scope to change but the size of the actual map to be easily assessable.

5. Topographic Maps River systems:
Topographic maps allow the reader to appreciate the physical form and terrain of a given area. Landforms, geologic features and structures can all be identified from a topographic map.
Rivers are visible as indicated lines.
The direction of flow is shown by ‘V’ shaped valleys on the contour lines. Rivers flow in the opposite direction to the ‘V’.
Use the elevation markers to confirm the river is flowing in a certain direction – GRAVITY causes water to flow towards lower elevations and eventually a body of water i.e. ocean

6. Topographic Maps Finding the GRADIENT or SLOPE:
“Slope is the measure of steepness or the degree of inclination of a feature relative to the horizontal plane. Gradient, grade, incline and pitch are used interchangeably with slope”
Earth scientists use the contour lines to distinguish between different landforms and features on the surface.
Calculating the gradient of an area can assist in estimating various earth science principles about the terrain and geomorphological systems operating.
The distance between each contour line can determine the relative steepness of the landscape.

7. Topographic Maps Topographic mapping & GIS:
Remote sensing is the art and science of recording, measuring, and analyzing information about a phenomenon from a distance.
Modern satellite and wavelength technology has allowed earth Scientists to take an even closer look at the surface and changes that occur beyond just our visible light capabilities.

8. Topographic Maps