How can I use topographic maps?
An overview of topographic maps and associated topics
Topographic maps as a way to visualize the surface of the Earth
Why should I become familiar with all aspects of topographic maps?
Topographic maps will be familiar to those of you who are hikers or outdoor enthusiasts; they are used to understand the landscape over which you will hike (or rock climb or ski, etc). They are also commonly used by field geologists for a variety of applications. The ability to read and interpret topographic maps is considered a basic skill for all geoscientists and geoscience students. Topographic maps are used to understand the shape of the land, whether a slope will fail, how glaciers are changing, and geologic history, among many other things. Geoscientists make and use them to construct geologic maps, to find the best building sites, to estimate where flooding will take place, and to determine the best sites for archeological or paleontological digs. Parts of this module teach you about how to read topographic maps so that you can complete other applications that these types of contour maps are used for.
Drawing a topographic profile is related to slope and understanding the shape of the land. Why would you want to draw a profile of the landscape? Many geoscientists like to visualize the shape of the land as if they had sliced through it. This helps them to see hazards, draw conclusions about the strike and dip of the geology beneath the land, among other applications. Parts of this module will walk you through the steps to making a topographic profile, something geoscientists do often.
Topographic maps pages
- Read elevations from a topographic map
The following are examples of the types of questions that ask you to read elevations from a topographic map.
- Determine the elevations of points 1-5.
- What is the height of the hill where line B (red) is drawn?
- Calculating slopes and gradients from a topographic map
The following are examples of types of questions that you might see in a typical question that asks you to plot points.
- Calculate the slope of line B (red) on the topographic map to the right.
- Determine which slope is steeper, line B (red) or line C (blue) on the topographic map to the right.
- Find the gradient of the road on the topographic map to the right.
- Draw a topographic profile from a topographic map
The following are examples of types of questions that you might see in a typical question that asks you to draw a smooth line.
- Plot elevations along the line A-B, connect the points with a smooth line to construct a topographic profile.
- Create a topographic profile across the summit of Mount Wenner.
More help with topographic maps
You can complete the pages linked above with no extra help. If you feel like you need more help, or more information about topographic maps , here are some links to help you think about topographic maps on the whole.
- A U.S.G.S. web page about the history and development of topographic maps
- Topographic map symbols from the USGS
- One of many sources for free downloadable topographic maps
- Some basic instructions on reading topographic maps.
- Compassdude.com is a very basic introduction to topographic maps.
- An extensive, free, online book based on the US Army Field Manual: "Map Reading and Land Navigation" that includes many of the skills presented here, but also many others.