You probably know that a magnetised compass and a paper map are part of the Ten Essentials (if you don’t, you need to go do some reading Missus or Mr). But what is the point of bringing along a topo map, or topographic map, if you don’t know how to read it? If you know how to read one, your map tells you a rich and detailed tale about the terrain you’ll be exploring.
Yup, that’s right, those squiggly lines do actually mean something.
Topographic Map Definition
Map showing natural and/or physical features of a landscape, including altidue contours. Also called a contour map
How Contour Lines Describe Terrain
Topographic maps provide much more detail than simple trail maps. While trail maps are useful for planning, topo maps give you the power to visualise three-dimensional terrain from a flat piece of paper. It’s a bit like magic really. This is due to the contour lines and other features that depict the area.
Contour lines do the following:
- Show you the steepness of the terrain
- Indicate the shape of the terrain
- Show you the exact elevation at regular intervals
- Contour interval lines tell you the change in elevation
- Show you a depression rather than a peak
Contour lines all connect points that share the same elevation. If you follow the line along the map, all that terrain will be at the same elevation. They often look like wonky circles or someone who hasn’t mastered the art of drawing straight lines yet.
When the lines are close together, the elevation is changing rapidly in a short distance. The terrain will be steeper here. Contour lines that are further from each other show that the elevation changes takes place over a longer distance. This means that the slope will be much more gentle.
In the above picture, you can see the differences between a steep incline and a gradual incline.
Quick Recap: The closer the contour lines are together, the harder you climb!
Index Contour Lines
Every fifth line is thicker. This is because it is an ‘index’ line that tells you the exact elevation. You can see this at some point along the line.
Those wonky circles and squiggly lines also show you the shape of the land. Roughly concentric circles are most likely showing you a peak, and areas between peaks are passes.
Have a go: Grab a topo map of an area you know well and see if you can match the terrain features with the contour lines on the map.
The change in elevation from one contour line to the next is always the same within the same map.
New Zealand maps tend to have either a 20 or 100-meter contour interval. A 100-meter interval simply means that each contour line is 100 vertical meters away from the next closest line.
The contour interval is found on your maps legend.
On an NZ Topo50map, the contours represent a 20m elevation gain, on an NZ Topo25, the contours represent 100m elevation gain.
A circle with tick marks inside it indicates a depression rather than a peak. You should also see elevations decreasing as you get near the depression.
This is a common feature on volcanoes such as Mt Tongariro, which you can see in the example below.
The level of detail shown on maps depends on the scale of the map. A small scale shows less detail than a larger scale map. This is because there isn’t as much room to cram everything in on a small scale map.
In New Zealand, topographic maps are made by Land Information New Zealand (LINZ). These maps are at a scale of 1:50 0000 which means one centimetre on the map represents 500 meters on the ground. These maps are known as Topo50 maps.
Topo50 maps are the most commonly used maps for hiking, navigation, search and rescue, emergency services and a variety of outdoor activities.
LINZ also produces smaller scale maps
- 1:250 000 NZ Topo250 maps (2.5 kilometres per cm on map)
- 1:1 million (10 kilometres per cm on map)
- 1:2 million (20 kilometres per cm on map)
These maps are useful for planning travel over large distances or for giving an overview of New Zealand.
Have a go: See what differences you can spot in the detail between the next two maps. What extra pieces of information does the second map show?
Learning to Read Your Topo Map
The map legend is chockablock with map-reading clues and navigational data. It is full of symbols and other mysterious bits and bobs to decipher.
Generally, green indicates denser vegetation, while light or colourless areas suggest open terrain.
You can see the difference between the above topo maps. The Ruahine Range is green due to the dense bush and Mt Tongariro is void of colour due to the fact that there is no vegetation. Streams and lakes are shown in blue which you can see in both maps.
The legend also lists key data like the map’s scale, contour and index line intervals, grid systems (used for more advanced navigation) and magnetic declination (needed to set up your compass).
Other features are also listed such as cultural and historic sites.
Have a go: read the legend of a topo map and see if you can spot the features in the land
Practice reading features from a map of a familiar area
Grab yourself a map of a familiar area and visualise how the terrain on the major landmarks relates to the contour lines.
Pick out features like:
- Cliffs either shown with a symbol (as shown in the legend) or lines very close together
- Ridgelines, which connect peaks and have contour lines that decrease in elevation on either side. You will also notice that much of the time these are colourless as they are above the bush line
- Valleys, the low-elevation areas between ridgelines
Practice makes perfect
Pull out your map at the trailhead, orient it correctly (see REI’s guide on How to Use a Compass) and mentally check off landmarks as you hike.
Regular map readers rarely get lost (unless they are reading it upside down).
Where to Buy Topo Maps
You can pick up a topo map from a variety of places.
Maps from Specialty Companies
Several companies produce enhanced topographic maps. They highlight key features and update details regularly. These maps are usually for more popular areas.
Additional features that can make a map more valuable include:
- Highlighted trails
- Elevation callouts
- Distances between trail junctions and landmarks
- Primitive trails
- Backcountry campsites
- Highlighted boundary lines
Offering similar advantages to mapping software, a rapidly growing number of websites offer you the option to customise and download maps. Some are free while others are subscription based.
Websites that have Topo Maps include:
- The Wilderness Magazine often has a topo map and trail notes for different tracks around the country. You can download these to your phone if you have the app
- The Department of Conservation website has maps of all the DOC huts and trails in the country
- Land Information New Zealand has backcountry maps as well as urban maps.
Check out Information Centres around the country for topographical maps as well as petrol stations, bookshops and the AA (no, not the AA that you sit in a circle with strangers on uncomfortable chairs in a drafty hall. This one is the Automotive Association of NZ. Unfortunate initial coincidence).
Learning to read and interpret a topo map is an essential backcountry skill. Once you have mastered this skill, the world is your oyster! Maps can literally save your life so it is imperative (always wanted to use that word in a blog post) that you learn how to read one properly and confidently.
It looks confusing at first, but once you get a feel for how it all works together, you’ll be a whizz in no time.
If you have any questions, make sure to leave them in the comments and I will reply as soon as I can,
Other useful Posts
- What is leave no trace and how to practice it
- The 10 essentials – be prepared for anything!
- 11 top tips for starting your first hike
- 27 hiking hacks (that you probably haven’t thought of)
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