Lab 8

Lab 8: Topographic Maps

Go to the following website: 

http://geology.isu.edu/geostac/Field_Exercise/topomaps/topo_map.htm

1. What is a map (please provide a complete definition)? (1 mark)

  A map is a way of representing on a two-dimensional surface, (a paper, a computer monitor, etc.) any real-world location or object. Many maps only deal with the two-dimensional location of an object without taking into account its elevation. Topographic maps on the other hand do deal with the third dimension by using contour lines to show elevation change on the surface of the earth, (or below the surface of the ocean).

2. What is a topographic map? (1 mark)

  The concept of a topographic map is, on the surface, fairly simple. Contour lines placed on the map represent lines of equal elevation above (or below) a reference datum. To visualize what a contour line represents, picture a mountain (or any other topographic feature) and imagine slicing through it with a perfectly flat, horizontal piece of glass. The intersection of the mountain with the glass is a line of constant elevation on the surface of the mountain and could be put on a map as a contour line for the elevation of the slice above a reference datum.

3. Why is a legend necessary for most maps? (1 mark)

The legend and margins of topographic quadrangles contain a myriad of other useful information. Township and range designations, UTM coordinates, and minute and second subdivisions are printed along the margins of the map. *Section numbers (from the PLS system) appear as large numbers within a grid of lines spaced one mile apart. The legend also contains a road classification chart showing different types of roads (paved, gravel, dirt, etc.).

In the table of contents on the left hand side, click Using Topo Maps and Map Scale to help with the next couple questions. There are seven rules that topographic maps have to obey (you can enlarge the figure on the right hand side to see...