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Interpreting map features

How to interpret topographic features

Being able to interpret how topographic features fit together in the landscape gives the user a much deeper understanding of the lay of the land and how to identify where they are and how to move through it.

On topographic maps, contours represent the shape of the land. Contour lines fit together in many different ways, and they form shapes which can be recognised by the user.

Features of the landscape that are useful to know are:

Elevation and slope Understanding how elevation and slope are depicted on topographic maps

Elevation and slope are the two elements that determine how landforms physically appear and connect.

Elevation
The ‘contour interval’ – the elevation between contours – is the vertical distance between adjacent contour lines. On 1:25,000 maps usually used by bushwalkers, contours are either 10 or 20 m apart.
elevation

For measuring between contour lines see here.

Slope (Steepness)
The rate of rise or fall of a terrain feature is known as its slope. The speed at which a bushwalking group can move is affected by the slope of the ground or terrain features. This slope can be determined from the map by studying the contour lines—the closer the contour lines, the steeper the slope; the farther apart the contour lines, the gentler the slope. Totally flat ground has no contour lines.

Four types of slopes that concern bushwalkers are gentle, steep, concave, and convex.

  • Gentle: Contour lines showing a uniform, gentle slope will be evenly spaced and wide apart. Easy walking.
    gentle-full

  • Steep: Contour lines showing a uniform, steep slope on a map will be evenly spaced, but close together. Very challenging, or impossible walking (i.e. contour lines may be so close that they create an impassable cliff line).
    steep-full
  • Concave: Contour lines showing a concave slope on a map will be closely spaced at the top of the terrain feature and widely spaced at the bottom. Bushwalkers going up the slope will find the terrain increasingly steep and challenging.
    concave-full
  • Convex: Contour lines showing a convex slope on a map will be widely spaced at the top and closely spaced at the bottom. Bushwalkers going down the slope cannot observe most of the slope or the terrain at the bottom, so extra care must be taken when route finding.
    convex-full

Common terrain features Understanding how common terrain features are depicted on topographic maps

All terrain features are derived from a complex landmass known as a ridgeline, not to be confused with a ridge.

The US Army states that “A ridgeline is a line of high ground, usually with changes in elevation along its top and low ground on all sides from which a total of 10 natural or man-made terrain features are classified”.[1] By comparison, a ridge is a sloping line of high ground.

Major terrain features include hills, saddles, gullies, ridges, and depressions, and they each have characteristic contour lines that make it easy to pick them out in the landscape.

  • Hills, peaks, knolls, mountains: A hill, peak, knoll or mountain is an area of high ground. From a hilltop, the ground slopes down in all directions. A hill is shown on a map by contour lines forming concentric circles. The inside of the smallest closed circle is the hilltop.
    • Hill = an area of high ground; generally, a smaller and rounder than a mountain, and less steep.
    • Knoll = small, rounded natural hill.
    • Mountain = a very tall hill, generally with a minimum size of 600m, but varies around the world.
    • Peak = a mountain with a pointed top.
    • Munro = a Scottish mountain taller than 3,000 feet (914 m).

hill-full

  • Saddle: A saddle is a dip or low point between two areas of higher ground. A saddle is not necessarily the lower ground between two hilltops; it may be simply a dip or break along a level ridge crest. When standing in a saddle, there is high ground in two opposite directions and lower ground in the other two directions. A saddle typically looks like an hourglass.

saddle-full

  • Gully: a gully is a stretched-out groove in the land, usually formed by a watercourse, and has high ground on three sides. Depending on its size and location water sometimes flows through it, from high to low. Contour lines forming a gully are either U-shaped or V-shaped. To determine the direction water is flowing, look at the contour lines. The closed end of the contour line (U or V) always points upstream or toward high ground. A valley is a large gully, often very flat, wide and open with a large watercourse running through it.

gully-full

  • Ridge: a ridge is a sloping line of high ground. When standing on the centerline of a ridge, there is usually low ground in three directions and high ground in one direction with varying degrees of slope. When crossing a ridge at right angles, there is a steep climb to the crest and then a steep descent to the base. When moving along the path of the ridge, depending on the geographic location, there may be either an almost unnoticeable slope or a very visible incline. Contour lines forming a ridge tend to be U-shaped or V-shaped. The closed end of the contour line points away from high ground.

ridge-full

On a map, a ridge is depicted as two contour lines (often of the same contour) running side by side at the same elevation for some distance. When the lines diverge, the ridge is either flattening out to a high plateau or continues to rise with additional contour lines. When the lines converge, the ridge is falling in elevation, creating a spur.

Closed contour loops represent hills or bumps along the ridgeline.
ridgeline_annotated

  • Spur: A spur is a short, continuous sloping line of higher ground, normally jutting out from the side of a ridge. A spur is often formed by two roughly parallel streams cutting draws down the side of a ridge. The ground will slope down in three directions and up in one. Contour lines on a map depict a spur with the U or V pointing away from high ground.

spur-full

  • Depression: A depression is a low point in the ground or a sinkhole. It could be described as an area of low ground surrounded by higher ground in all directions, or simply a hole in the ground. Usually, only depressions that are equal to or greater than the contour interval will be shown. On maps, depressions are represented by closed contour lines that have tick marks pointing toward low ground.

pit-full

  • Cliff: A cliff is a vertical or near vertical feature; it is an abrupt change of the land. When a slope is so steep that the contour lines converge into one “carrying” contour of contours, this last contour line sometimes has tick marks pointing toward low ground (image below). Cliffs are also shown by contour lines very close together and, in some instances, touching each other.
    cliff-full
    Topographic maps cannot always be used to identify cliffs, however, particularly on those with 20m contour intervals, and hence some steep areas require careful negotiation.

Tips, tricks and common mistakes Some tips, tricks and common mistakes to avoid when reading topographic maps

The real art of map reading comes with interpreting how individual landscape features fit together in the terrain: saddles connect ridges to knolls to cliffs; gullies form into rivers and valleys. Interpreting how contour lines fit together helps understand the lay of the land and be able to navigate through it.

The big picture

1 - hill, 2 - valley, 3 - ridge, 4 - saddle, 5 - depression, 6 - gully, 7 - spur, 8 - cliff, 9 - cut, 10 - fill

1 – hill, 2 – valley, 3 – ridge, 4 – saddle, 5 – depression, 6 – gully, 7 – spur, 8 – cliff, 9 – cut, 10 – fill

This image describes a landscape by contours. In words:
Running east to west across the complex landmass is a ridgeline. A ridgeline is a line of high ground, usually with changes in elevation along its top and low ground on all sides. The changes in elevation are the three hilltops and two saddles along the ridgeline. From the top of each hill, there is lower ground in all directions. The saddles have lower ground in two directions and high ground in the opposite two directions. The contour lines of each saddle form half an hourglass shape. Because of the difference in size of the higher ground on the two opposite sides of a saddle, a full hourglass shape of a saddle may not be apparent.

There are four prominent ridges. A ridge is on each end of the ridgeline, and two ridges extend south from the ridgeline. All of the ridges have lower ground in three directions and higher ground in one direction. The closed ends of the U’s formed by the contour lines point away from higher ground.

To the south lies a valley; the valley slopes downward from east to west. Note that the U of the contour line points to the east, indicating higher ground in that direction and lower ground to the west. Another look at the valley shows high ground to the north and south of the valley.

Just east of the valley is a depression. Looking from the bottom of the depression, there is higher ground in all directions.

Several spurs extend south from the ridgeline. They, like ridges, have lower ground in three directions and higher ground in one direction. Their contour line U’s point away from higher ground. Between the ridges and spurs are draws. They, like valleys, have higher ground in three directions and lower ground in one direction. Their contour line U’s and V’s point toward the higher ground.

Two contour lines on the north side of the centre hill are touching or almost touching. They have ticks indicating a vertical or nearly vertical slope or a cliff.

The road cutting through the eastern ridge depicts cuts and fills. The breaks in the contour lines indicate cuts, and the ticks pointing away from the road bed on each side of the road show fills.

Common mistakes
Here are some tips and tricks to identify between standard features.

  • Spur vs. gully: Contour lines on a map depict a spur with the U or V pointing away from the high ground; for a gully, the closed end of the contour line (U or V) always points upstream or toward high ground.

Spur

Spur


Gully

Gully

  • Knoll vs. depression: for knolls, contour lines form concentric circles, and there is lower ground all around, whereas depressions have closed contour lines with tick marks pointing toward the low ground.

Knoll

Knoll


Depression

Depression

  • Saddle vs. ridge: When standing in a saddle, there is high ground in two opposite directions and lower ground in the other two directions. When standing on the centerline of a ridge, there is usually low ground in three directions and high ground in one direction with varying degrees of slope. Be careful not to confuse ‘ridge’ with ‘ridgeline’ here: a ridgeline is a line of high ground, which can rise and fall through saddle features.

ridgeline_annotated2

Practicing
Map reading takes practice. One of the easiest ways to do this is to become aware of the shape of the surrounding land at all times, even when driving and walking through an urban area. Most navigation and map reading is about matching up the form of the land with that on the map. Practice recognising and naming key features (knoll, hill, spur, ridge, cliff, valley, etc.). Take maps on all bushwalks and follow the route on the map, even if it’s well signposted. Look at the map regularly and match it with the surrounding landscape.

Some bushwalkers enjoy taking part in Rogaine competitions to improve their navigation. The Bushwalkers Wilderness Rescue Squad also runs an annual navigation competition in NSW.

Subtle features Recognising subtle features on topographic maps

There are subtleties to map reading that take time to develop. Some common things to watch out for include:

  • Implied knoll: A bump or small hill that is too small to generate it’s own closed loop contour. Occurs in places where two ridge lines diverge and converge or on the top of a hill where the contour lines are furthest apart.

implied_knoll

  • Implied saddle: The opposite of an implied knoll. An implied saddle is a saddle that is not formed enough to have two parallel contours cross the ridgeline and connect.

implied_saddle

  • Minor gully: A dent in the side of a slope or ridge often too high for a proper water course to form.

subtlegully2

  • Minor spur or outcrop: a bump on the side of a ridge or slope that’s too localised or flat to form a proper spur.

minor_spur

Map measurements

Taking measurements from a map

Topographic maps enable the user to take measurements of distance and elevation. The accuracy of these measurements can be in the order of metres depending on the scale of the map.

The following measurements can be taken from a standard topographic map:

  • Distance
  • Bearing
  • Elevation change

Distance Measuring distance from a map

Calculating the distance between two points on a map is done by measuring the distance with a ruler in centimetres, then converting it to metres or kilometres.

For a straight-line distance between two objects, use a ruler to measure the distance between the points. If the distance is curved, use string along the curve, then lay it on a ruler to measure the length of the string.

Find the scale bar on the map. It might be written as a fraction (1/25,000 or 1:25,000) or a bar scale. Both provide a conversion factor that must be applied to calculate the real distance. A 1:25,000 scale map says that for every 1 cm on the map it represents 25,000 cm on the ground. So if the distance measured on the map is 25 cm, the distance on the ground is 25×25,000=625,000cm or 6.25km.

The precise formula is:
(Map distance (in centimetres) x denominator of scale)/100,000 = Real distance (in kilometres)

Some compasses include a converted scale on one side of them where the measurement for 1:25,000 maps or 1:50,000 maps is in kilometres already. Having a converted scale on hand can be useful for getting rough estimates of distance quickly. Alternatively, on 1:25,000 maps, each grid represents a km, so it’s possible to eyeball the map to get a rough distance estimate without using a ruler. Using the compass or eyeballing the map is most practical out on a bushwalk.

Bearings Taking bearings from a map

A bearing is a number in degrees that represents the direction of one point relative to another. It’s helpful for navigating between two points or triangulating a location. On topographic maps, the bearing is relative to grid north.
compass-on-map_new1

For calculating the bearing of point B relative to point A, follow these steps (note that the map does not need to be oriented):

  1. Draw a line on the map between points A and B.
  2. Line up compass with the directional arrow pointing from A towards B. Make sure that the direction is correct, otherwise the bearing will be 180° out.
  3. Rotate the movable dial so that large red arrow on the dial is parallel to the North/South grid lines on the map, and the arrow is facing north. Ignore the magnetic needle in this step. Make sure that the dial is aligned with grid north, not grid south (easy to do if the map is upside down), and that the directional arrow hasn’t slipped out of place during this step.
  4. Read the dial to give a number between 0° and 360°, clockwise from north.

Note: The bearing taken from a map is the grid angle, but bushwalkers must use the magnetic angle when navigating in the field. Hence a grid bearing must be converted to a magnetic bearing before using it to navigate.

Elevation change Measuring elevation change from a map

Changes in elevation can be calculated using contour lines. Here’s an example below.
elevation-change

The lower index contour line is numbered 200, which means any point on that line is at an elevation of 200 meters above mean sea level. The upper index contour line is numbered 300, or 300 meters. A bushwalker traveling from X(a) to X(b) will go up in elevation. The exact amount of change can also be calculated: Point X(a) is located on the second intermediate contour line above the 200-meter index contour line. The contour interval is 20 meters (there are four intermediate contour lines of 20 m between the 200 m and 300 m contour line) and hence the bushwalker will go through an increase in elevation of 40 m (240 m to 280 m).

To determine the elevation to a hilltop, point (c), add one-half the contour interval to the height of the last contour line. In this example, the last contour line before the hilltop is an index contour line numbered 300. Add one-half the contour interval, 10 meters, to the index contour line. The elevation of the hill would be 310 meters.

Grid references

Reading and plotting grid references

A grid reference indicates a location on a map in terms of numbered vertical and horizontal grid lines. Grid references are useful for sharing routes, and quickly communicating to emergency services. Bushwalkers often share grid references of campsites or camp caves, obstacles or challenges on a walk, where to get through a cliff line, where to cross a river or what route to take. Orienteering competitions also provide information on their flag locations using grid coordinates.

To share a grid reference, the name of the map must be given, plus the X and Y coordinates. Users must also be clear on the reference system used.

Reference systems Understanding reference systems used by bushwalkers

When sharing a grid reference, bushwalkers must be clear on the reference system being used, else the points will not necessarily match up. Maps that show the same terrain can be made using different datums and projections {link to datum and projection chapter}, meaning that the grids do not necessarily line up. 

For example, compare the images of the Megalong Valley below, and notice that the location of all features relative to the grid lines is different. This is because the first map below uses an older datum than the one below that. 

AMG

AMG


GDA

MGA / GDA94

Any given reference system is based on a datum, a 3D representation of the earth, and datums differ in how they represent land and where the location of the central frame is. Two points can be out by as little as a few hundred metres, or as much as several kilometres if there is confusion over the reference system in use.

Maps usually have an information section that identifies the map datum and projection, along with the publisher and copyright information. When communicating a grid coordinate, state the coordinate system first, then the grid coordinates.

In NSW, the 1:25000 topographic maps use either the AMG or the MGA coordinate systems.

  • AMG: The AMG is the Australian Map Grid 1966/1984 system and was used on the old series maps, mostly distributed circa the 1980s. The AMG reference system uses the Universal Transverse Mercator projection of the Australian Geodetic Datum 1966.
  • MGA: The MGA is the Map Grid of Australia 1994, and is used in all the new series maps. As a general rule, all the new series maps have an aerial photo image on the reverse. The MGA reference system uses the Universal Transverse Mercator projection of the Geocentric Datum of Australia 1994 (GDA94).

The AMG system was used until roughly the mid-90s when it was replaced with the MGA system, which is more compatible worldwide as the GDA 94 datum is almost identical to the WGS84 datum used in GPS (Global Positioning Systems). The result of the change from the AMG system to the MGA system is a shift of approximately 200 metres in a northeasterly direction.

While being off by 200 metres doesn’t sound like much, in the bush this can be disastrous for an emergency operation, or cost a bushwalking party serious time delay. That’s why it’s important to communicate which reference system is being used and to know how to convert between them. In an emergency, it may be possible to get enough mobile phone coverage to contact the emergency services and communicate the location of rescue.

Converting between AGM and MGA

The shift between AGM and MGA is approximately 200m in a northeasterly direction. The images below give an example of the shift relative to the UTM Northing and Easting grid lines.

AMG

AMG


GDA

GDA

To convert between grid points, users add 100 m to the Eastings, and 200 m to the Northings. As a practical example, for a 6-digit grid reference, add 1 to the Eastings (the first three digits), and 2 to the Northings (the second three digits). So the junction of the two roads Hampton-AMG436645 becomes Hampton-MGA437647. The examples below have more information on reading grid references.

Since all objects on a map remain the same relative to each other between the two systems, bearings do not change.

Reading a grid reference from a map Learning how to read a grid reference from a map

Maps have numbered vertical and horizontal grid lines that enable the reader to identify and communicate a particular location on the map. The vertical lines are aligned with grid north, and the horizontal ones are exactly perpendicular to the vertical lines.

The Universal Transverse Mercator (UTM) system, which describes a point in terms of metres, is most commonly used by modern topographic maps. And this is the system described here.

In the UTM system, the vertical lines are called Eastings (i.e. they help locate how far east the point is), and the horizontal lines are called Northings (i.e. they establish how far north the point is). Most maps also include the Longitude and Latitude of the map at the corners (i.e. a reading in degrees, minutes and seconds).
EastingsNorthings_annotated

A UTM grid reference tells the reader how East and how far North to go on the map. It consists of two parts – the Easting digits, and the Northing digits – and always has an even number of digits. Determine the number of Eastings and Northings digits by dividing the whole grid coordinate by 2. The more digits, the more accurate the grid reference.

When reading a grid reference, Eastings always come first, followed by the Northings. A simple way to remember this is the saying ‘cross the creek before going up the tree’, that is, go horizontal first, then vertical.

Example 1: Describing the location of the hill labelled 619. The 619 refers to the height of the hill in metres. Often, bushwalkers describe a hill by its height, unless another name is written on the map (typical for popular and distinctive hills). In this example, since the hill has no name it can be called Hill 619.
Colo_Hill619_annotated

On the 1:25,000 map above, each square is 1km wide and high. The Northing and Easting lines are all numbered. Ignoring the small numbers either side of the black numbers (explained later), notice that the lines increase by one unit along the bottom (68, 69, 70, 71…) and up the left-hand side of the map (05, 06, 07, 08…).

A four digit grid reference (2 digits for the Easting, and 2 for the Northing) is a crude measure of the location with an accuracy of one square kilometre. It describes the intersection of two lines. The closest intersection to Hill 619 is the intersections of the Easting line 69 with the Northing line 06. Hence Hill 619 has a four digit coordinate of 6906 plotted as a white circle below.
Colo_Hill619

However, since the margin of error in a four digit this grid coordinate is 1km square (outlined in orange), this reference could describe any of the features from the hill in question, to a gully or a creek junction. To more accurately describe Hill 619, it’s best to use a six-digit grid reference.

Draw perpendicular lines from Hill 619 to intersect with the Easting and Northing lines. Then measure how far along the grid the lines are. For the Easting, the line crosses 6/10th of the way along the grid. Hence the Easting coordinate is 686. For the Northing, the line intersects 1/10th of the way up. Hence the Northing coordinate is 061. The Hill has a six-digit grid reference of 686061. Since the map is an old map (‘1:25,000 Colo Heights’) and uses the AMG reference system, the six-digit grid reference is ‘Colo Heights AMG-686061’.
Colo_Hill619_markers

A six figure coordinate has six figure grid reference an accuracy of 100 m2, indicated in the orange square box. This area of error is much smaller than the search area provided by a four-digit grid reference.
Colo_Hill619_little orange

Example 2: Bonnum Pic.
BonnumPic_annotated

Care must be taken to quote all the zeros in the right place. In this example, the Northings have a zero at the front. The 6 figure grid reference is therefore 477060. Since the map is a new edition map and uses the MGA reference system, the six-digit grid reference is ‘Hilltop MGA-477060’.

Example 3: Hill 2122. The hill lies on a grid line meaning that for a six-digit grid reference, the Easting has to include a zero at the end. Hence the six-digit grid reference of Hill 2122 is 010977. Since the map is an old map (‘1:31680 Caoura’) and uses the AMG reference system, the six-digit grid reference is ‘Caoura AMG-010977’.
caoura-map_circle-and-lines

Example 4: Hill 731.
Hilltop731_annotated

An 8-digit grid reference is even more accurate than a 6-digit one and has an accuracy of 10 m2. Supplying accuracy to the nearest 10 metres involves splitting up the grids into 100-tick increments.
Hilltop731_annotated_lines
Hill 731 has an eight-digit grid reference of 49029349. Since the map uses the MGA reference system, the eight-digit grid reference is ‘Hilltop MGA-49029349’.

UTM zones: Identifying the region
UTM divides the earth into 60 zones each with 6 degrees of longitude, and 20 designators each with 8 degrees longitude.

© Jan Krymmel, 26 Jan 2007 / Wikimedia Commons / CC-BY-SA-3.0

© Jan Krymmel, 26 Jan 2007 / Wikimedia Commons / CC-BY-SA-3.0

Australia falls between zones 50-56, and Sydney is in 56H.

A 6-digit grid coordinate system works well among bushwalkers to communicate points of interest and routes, and Bushwalkers use a shortcut to identify the region in question. They refer to the name of the map in question, a practical and quick solution for sharing information.

However, on a global scale, there would be many identically-numbered grid locations unless the specific UTM zone is also reported, along with a context for the Easting and Northing lines.

In the corner of all maps, the Eastings and Northings are given additional small numbers before the main ones that identify the lines.
hilltop731_annotated_circles
While the small numbers aren’t usually quoted by bushwalkers for six- or eight-digit grid references, they will appear on a GPS reading. GPS Eastings and Northings always include an accuracy down to the nearest metre. Hence for every square kilometre, the accuracy has to be to 3 digits for Eastings and Northings, something that is hard to do when reading off a map, but if given these grid coordinates, it’s possible to plot accurately.

Hence, the full coordinates of Hill 731 are Zone 56H, 0269210mE, 6316890mN. This is the same eight-digit grid calculated in example 4 above in orange.

Plotting a grid reference on a map Learning how to plot a grid reference on a map

Plotting a grid reference on a map is the reverse process of reading it on the map.

Example 1: Plotting the grid reference ‘Caoura AMG-041948’, the junction of a creek with a major river.

The reference 041948 is a six-digit grid reference with a 041 Easting and 948 Northing. Find the 04 Easting line and follow it 1/10th of the way further east. Then find the 94 Northing line, and follow it 8/10th of the way further north. The grid point is the junction of Paradise Creek with the ShoalHaven.
Caoura Map_arrows

Example 2: Plotting the grid reference for Mt Wangandarry ‘Hilltop MGA-48259765’, a trig point.

The reference 48259765 is an eight-digit grid reference with a 4825 Easting and 9765 Northing. Find the 48 Easting line and follow it 25/100th of the way further east. Then find the 97 Northing line, and follow it 65/100th of the way further north. The grid point is the top of a knoll on a large flat hill top.
Hilltop745_arrows

Tools
Coordinate plotting tools can aid plotting grid points on maps. Grid tools enable the user to keep an exact right-angle position as they find the coordinates they’re looking for, and the user does not need to draw lines on the maps.

A UTM plotting grid is one option. Alternatively, a corner style tool or simple ruler. Ensure that any map plotting tool has the right scale (note that American sellers stock 1:24,000 tools, not to be confused with the more common 1:25,000 series used in Australia).

Using a GPS to identify and plot locations How to use a GPS to identify and plot your location on a map

GPS units are an excellent tool for identifying and plotting locations along a bushwalk. GPS units can also be loaded with a basic topographic map and route plan at home, and users can follow the route in the field. Alternatively, users can identify specific locations along the walk and translate them back onto a topographic map to double check their location and accuracy of navigation.

GPS units act as an additional navigation tool to traditional map and compass. They typically give accuracy up to 20 m but rely on good satellite coverage. GPS units fail in regions where the sky is partially or wholly obstructed (caves, cliff lines, canyons).

Before use set the GPS unit to the correct Geographic Coordinate System, based on the type of maps being used. The most common system that bushwalkers use is the UTM/UPS system (not latitude/longitude). Then select the appropriate datum: for new series maps use WGS 84 (or GDA 94 as they are essentially the same); for old series maps use AGD66. If unsure, read the fine print in the publication details of the map. All datum and reference modifications on a GPS can be made in the ‘settings’ section.

Reading a grid reference on a GPS

A GPS grid reference looks something like this:
location
It includes information on the Geographic Coordinate System used (UTM), the location zone (56H), the Eastings (0706832) and the Northings (4344683). Eastings are always given first.

The ‘706’ part of the Easting information refers to a major Easting line, and the ‘832’ gives the location down to the nearest metre. The ‘4344’ part of the Northing information refers to a major Northing line, and the 683 gives the location down to the nearest metre in the grid.
hilltop745_with-numbers_56

Translating a GPS reading onto a map

Example: Finding the GPS coordinate Zone 56H, 0304920mE, 0695440mN.

The map below is in Zone 56H. Major Easting lines are 04, 05, 06, etc. and all have a ‘3’ at the start. Major Northing lines have 95, 96, 97, etc. Eastings have a ‘3’ prefix shown on the map, which is ‘03’ in the GPS coordinates. Similarly, the Northing lines have a ‘6’ prefix shown on the map, which is ‘06’ in GPS coordinates.
Hence, the 8-digit grid reference is 04929544. Follow the Eastings along to the 04 line, and then 92/100th further east. Follow the Northings to the 95 line and 44/100th further north.
The location is Mount Woolnough.
Caoura Map_arrows_two

Map care

How to care for your maps

Maps are amazingly detailed descriptions of the land and very useful for navigating in the bush, but they are vulnerable to weather, and poor care. Torn, damaged maps are harder to read and can leave a group in a tricky situation if they are relying on a single map that gets damaged.

Since maps also may have to last a long time, it helps to take care of them. Some bushwalkers choose to use photocopies instead and transcribe routes/passes and notes to the originals at a later stage. Ensuring that there are backup maps in the group is also very sensible as it’s easy to drop a map in water or lose it in thick scrub.

A pencil is recommended for marking routes or passes on a map. Use light lines so they may be erased quickly without smearing and smudging or leaving marks that may cause confusion later. Back home, consider going over the pencil additions again with a harder pencil or ink pen.

Copying The legalities behind photocopying maps

Photocopying sections of a map and using them in the field is a good way of protecting the original. Under copyright laws, a certain amount of photocopying of maps for personal use is ok, although it is a bit of a grey area. Some maps give permission for photocopying under “fair dealing”, others specify that no part of the map may be reproduced. Bushwalkers intending to photocopy maps are advised to check with the Australian Copyright Council, and/or the producers of the map.

The main disadvantage of using photocopied maps is that any handwritten notes made during the trip have to be transcribed to the original. Transcribing back and forth introduces errors. The other issue is that writing can be harder to see on a photocopy. Best to make sure that all notes are made in clear black pen, and the writing is easily legible.

Map case Why map cases are helpful

Maps are documents printed on paper and require protection from water, mud, and tearing. To prevent maps from getting damaged, where possible, use a waterproof map case, or keep it in a pocket, or in some other place where it is handy for use but still protected.

Choose a map case that is waterproof, and has a cord so that the map can rest around the neck. Ideally, select a map case that is large enough to fit two sections of the map, and provided the map is folded correctly, it’s easy to transition between segments even in bad weather.

Folding maps How to fold topographic maps

Shop-bought maps are typically folded in a peculiar way that means the user has to open up the entire map every time they move off one folded section and onto another. On some trips this can happen as often as once and hour. And while it may be possible to get away with unfolding and refolding the map every few kilometres in good weather, it gets much harder in the rain and wind.

For bushwalkers, a better technique is to fold the map down the middle and then concertina it. Do this in the comfort of the living room at home rather than the bush to make sure that the map creases are all folded neatly.

The US army also recommends the above method (diagram below, left image) or folding the map small enough to fit in a pocket (diagram below, right image). The folded map is still available for use without having to unfold it entirely.
folding-maps

Digital maps

Using digital maps on a bushwalk

While some people love owning a physical map collection, others prefer to read from a phone or iPad, or print their digital maps as they need them.

The advantage of using a digital map is that it’s possible to get the information for very cheap or free depending on the region. Digital maps can be printed, meaning that bushwalkers only need to carry with them the exact area they need to use. It’s also possible to access maps on smartphones and tablets, and since most people have these devices, so that’s an easy way to give access to many.

The disadvantage of using a digital map from a digital device is that it’s more complex to make notes and draw tracks on digital devices. Also, the battery of the device can run out, and it can be challenging to use the device in the rain. If printing out digital maps, the print quality may not be high enough to read subtle features.

Use of digital maps has to be carefully weighed up by thinking through the likely terrain, and trip.

Sources Where to source digital maps from

Digital maps can be split into four categories:

  • Basic digital maps
  • Detailed topographic that can be printed out from computer
  • Detailed topographic that can be read from a device like a phone or GPS
  • Bushwalking specific

Basic Digital Maps
These digital maps are not topographic. They show some fire trails, some walking trails but are not informative enough for navigating on anything more than a well known, well-signposted track. They can be helpful to get to the start of a walk i.e. excellent urban street accuracy, pretty good for some more remote fire trails and some campgrounds.

Detailed topographic maps: printable from computer
These maps have excellent topographic information for navigating in remote areas, and can be printed out from a computer and used on a bushwalk.

Detailed topographic maps: for use on smartphones, tablets or GPS units
These maps have excellent topographic information for navigating in remote locations, and can be read from phones or GPS in remote areas.

Bushwalking-specific
Bushwalking-specific maps offer information on specific routes or tracks and can be helpful when looking for bushwalking-specific track information. Wildwalks, NSW’s most comprehensive collection of Bushwalking track notes and maps; “Topo not to be” maps, a site for bushwalkers to map and share suggested tracks; Tom Brennan’s canyoning maps, marking major canyoning areas around Sydney.

Planning and field use Things to think through when going digital

If planning to use digital maps for a walk, make sure to download or print out the correct maps before the start of the walk where there may be little or no reception. Ensure that the print quality is high enough to read contour lines and features accurately and that any electronics have enough battery life (and spares!) for the entire trip.

In the field, make sure electronic devices are waterproof, dirt proof (e.g. water protection devices for phones), and that there are backups (spare batteries, extra devices).

For printed out maps – carry an extra set in case one set gets lost. Always print a larger map area than expected to use in case plans change.

Aerial imagery

How to use aerial imagery on a bushwalk

Aerial imagery is remarkably easy to come by these days and can be extremely useful in identifying interesting bushwalking features, potential routes and vegetation thickness. It’s easy to spot urban areas, man-made buildings and tracks and possible to determine elevation via shadows.

Aerial imagery means any images taken from an elevated position, including photography from helicopters, fixed wing aircraft or drones, right through to air balloons, parachutes and satellites.

A few free sources include:

Google Maps also gets its high-resolution images of cities from aircraft flying at 240 to 460 m, and the rest from satellites. LANDSAT satellites have been pivotal in providing accurate environmental data about the earth’s surface and in 2016 google earth has released worldwide images sourced from Landsat 8. Most of the satellite images are no more than three years old, meaning that the user can be confident that the information is reasonably accurate and current.

Reading and interpreting How to read and interpret aerial imagery

Just like topographic maps, manmade and natural features can be identified on aerial images. Aerial images show texture, shadow and patterns only. They do not usually include names of landmarks, roads or settlements, or information about elevation.

Landforms
Shadows help to identify elevation and relief on aerial photos. Shadows that fall outwards indicate higher elevations such as hills or mountains, whereas shadows that fall inwards indicated riverbeds, creeks and gullies. The rate of shadow appearance and disappearance along a ridgeline can determine the slope and steepness of features.

Water courses
Rivers are wide dark grey lines with many curves and bends in them. Side creeks flow into them. The v-shape of the connection between a side creek and the main creek always points downstream. Hence the reader can determine flow direction.

The colour of clear and muddy water bodies is different due to different amounts of reflected sunlight. Since clear water reflects less sunlight than muddy water, muddy water appears lighter in colour. Sandy soil also looks lighter than humid soil surfaces.

Aerial images can also give an indication of whether a water source is perennial or non-perennial, helpful when planning water sources on a walk.

Vegetation
Natural vegetation and grasslands usually have dark tints and a diverse pattern. Crops or plantations are identified by their unnaturally straight pattern of growth and patchwork appearance of cultivated lands. Tall crops appear darker in colour than small crops. Cultivated vegetation usually has a smooth, fine appearance, whereas natural bushland is dotted, and mountainous areas rough.

Manmade
Manmade objects tend to be evenly distributed with straight edges. Broad grey lines with few bends in them are major bitumen roads. Secondary roads are generally narrower with more curves. Fire trails may have a brown/orange/red tinge to them depending on the soil and road surface. Railway lines are small grey lines with long, smooth curves. Roads connect up perpendicular to each other while railway lines gradually merge.

Planning Using aerial imagery to plan a trip

Aerial imagery can be helpful in conjunction with topographic maps. They give an overview of the area, and able the user to see different patterns than on a topographic map.

From a bushwalking perspective, aerial images can be helpful to identify:

  • Clear ridges for easy walking
  • Dense scrub vegetation to avoid
  • Potential canyons, caves and other rock formations of interest
  • Perennial and non-perennial water sources for managing water needs
  • Cultivated (i.e. private) properties where bushwalkers cannot go without permission
  • Clear areas as potential campgrounds, or equally cliff-lines with potential camp-caves
  • New or altered fire trail or roads not shown on topographic maps

In NSW, bushwalkers use aerial imagery to detect canyoning areas. Often, the 10-20m topographic contour maps provided by the lands department are not accurate enough to determine if a creek line has or doesn’t have canyon features. Aerial imagery gives a reasonable indication of the depth of the cliff and can be helpful to figure out if the area is worth exploring.

Different ‘Ways’

Recognising different kinds of pathways, tracks and trails in the bush

There are many different types of bushwalking pathways, tracks and trails across Australia. Some routes have proper concrete paths, while others are merely the faintest trace of a track. Collectively, they are known as ‘ways’, a rather awkward and confusing word considering it has other meanings too! Nevertheless, it’s the best word to describe tracks, trails, sealed pathways, metal boardwalks and so on.

While some ‘ways’ are well maintained with signposts and facilities, others have irregular signposting or none at all. Some, but not all ‘ways’ are marked on maps, distinguished by different colours and line thicknesses.

Recognising from a map the different ‘ways’ the route follows is helpful. If you have a sense of how well-defined (or not) the route is, you’ll be well prepared for sections that are vague or not well signposted. Hence if something different appears, then alarm bells sound. It gives you time to stop and double-check that you’re still going the right way.

Sealed road Features of a sealed road

Sealed roads are recognised as properly formed and constructed road surfaces made with materials such as tar, bitumen, or concrete.

Some bushwalks make use of sealed roads to connect between sections of bush or national parks. Take care of vehicles and other motor traffic when using these roads. Walk on the right-hand side of the road to face oncoming traffic.

Sealed roads are typically depicted as solid red lines on topographic maps.
urbanroads – red

Unsealed road Features of an unsealed road

Unsealed roads are categorised as routes accessible by vehicles that are not sealed, metalled, or gravel roads.

Bushwalks will commonly use unsealed roads to connect between different sections of bush. As with sealed roads, take care of vehicles and other motor traffic when using these roads. Walk on the right-hand side of the road to face oncoming traffic.

Unsealed roads are typically depicted as solid orange lines on topographic maps:
urbanroads – orange solid

Management trail Features of a management trail

Management trails are used by land managers to access the areas they look after. They are not generally open to public vehicles. Management trails include fire-trails, which have strategic importance for fighting bushfires. They are usually an unsealed surface, about the width of a 4×4 car, with tire markings or ruts on the trail. Fire trails have contour banks to control erosion and track degradation, and sometimes passing bays or areas for vehicles to turn around.

Many bushwalks follow firetrails as they provide relatively easy walking. Although vehicles are rare, still take care when walking these roads.

Management trails are typically depicted as dashed orange lines on a topographic maps. Longer orange dashes indicate it is a vehicular track. Shorter orange dashes indicate a four-wheel drive track.
FireTrail vs Tracks – orange dashed

Path Features of a path

Paths are sealed walkways. They are generally flatter trails, and some are wheelchair user accessible.

In Australia, only a few of these paths exist, and they are generally short distances to a lookout.

Sealed paths, boardwalks and tracks are not generally drawn differently on topographic maps. They are represented by dashed black lines.
FireTrail vs Tracks – black  2

Boardwalk Features of a boardwalk

Boardwalks are used in areas with sensitive vegetation or boggy, muddy walking areas. They are quite common in Tasmania, as well as wetland areas. Sealed paths, boardwalks and tracks are not generally depicted differently on topographic maps.
FireTrail vs Tracks – black (3)

Track Features of a track

In Australia, a track is an unsealed pathway (except Victoria, where a ‘management trail’ is a ‘management track’, and a ‘walking track’ is a ‘walking trail’). Many bushwalks are tracks, some with better signposting than others.

Sealed paths, boardwalks and tracks are not generally depicted differently on topographic maps.
FireTrail vs Tracks – black 1

Faint tracks Features of a faint track

Faint tracks are standard on Grade 5/6 walks. These tracks might be overgrown, poorly maintained, or never a track in the first place but just a pad that has developed over time. Sometimes, animals will create tracks across ridgelines or down to waterways that provide easier walking for bushwalkers.

Faint tracks are generally not depicted on topographic maps.

Following the plan

How to follow a bushwalking plan

Before starting any bushwalk, you will make a plan. Then on the bushwalk, the navigation side of things is about following that plan, and updating it if things change.

Micro-navigation How to micro-navigate

Micro-navigation is when a navigation task is broken down into small pieces. A whole journey comprises of an infinite number of micro-navigation decisions, the result being getting from point A to point B.

Micro-navigation involves noticing the tiniest of features on a map. Things like, for instance, the number of twists in a river, a subtle change in the direction of a ridgeline, an implied knoll. Maps are a wealth of information once you start to examine these details, and they provide a much clearer picture on how you are traveling through the landscape.

Being able to micro-navigate is highly advantageous in poor weather conditions too. For instance, when visibility is poor, being able to recognise subtle nearby features could make the world of difference to understanding where you are in the landscape.

Group navigation Why your input is so important

When you’re starting out, it’s easy to feel quite self-conscious about your navigation skills compare to others that have been practicing for longer. So it’s easy to let someone else take the lead and make decisions. Remember, everyone has to start somewhere, and navigation is one of those things that only gets easier with practice.

Never be afraid to shout out when you don’t think things make sense. The more people in the group that keep an eye out for stuff, the less likely you are to go wrong. So many groups have blindly followed the person at the front only to realise half an hour later that they’ve gone in entirely the wrong direction! A short two-minute conversation to figure out where the group is on the right way can save hours of backtracking. Also, by speaking up, you’re making sure that the whole group agrees with the route decision, and encourages everyone to think about the landscape and where the route is going.

Even if you are not actively following the map on a bushwalk, follow the shape of the land and make a mental note of features you pass. Becoming familiar with these landforms trains the brain to spot quickly those features that most people would miss. A memory of the landscape is extremely useful if the group has to backtrack.

Staying Found

How to stay found on the map

The best navigation advice is simple: never get lost! Sounds a bit stupid, but it’s true. Navigation is incredibly hard when you have to figure out where you are every hour. Better to know where you are at all times by regularly checking the map with the surroundings.

Bushwalkers that regularly follow the map are more likely to pick up things that don’t seem right. They’re keeping an eye out for where they are in relation to landforms, the direction they are traveling in, and how it changes. They’re also watching the changing distance between their current location and where they want to be.

Keeping a keen eye on the map is the best way to know where you are at all times. Here are a couple of ways to do that:

Orientating the Map How to orientate the map in the direction of travel

It can be challenging to match a map up with the terrain, particularly when your brain has to make additional calculations about the orientation of the map relative to the landscape. At some point in our lives everyone has tried to stand on their head to make sense of whether a map is telling them to go right or left. People naturally find it easier to relate a map to the surroundings when everything that is to our left on the map matches everything that is to our left on the ground. Orientating the map in the direction of travel makes life a lot easier.

This is the key to orientating a map: placing it to line up neatly with the features on the ground. Many navigation courses make a big deal about this, claiming it’s the first thing that anyone should do before navigating. In reality, bushwalkers will rarely orientate the map accurately with a compass, unless for interest to figure out the exact names of distant peaks. Instead, they tend to orientate the map so it’s right by eye (terrain association) because it’s much quicker and flexible, and relies on the user understanding what they’re reading on the map, not just blindly following a bearing.

In short, there are two ways to orientate a map, depending on how accurate it needs to be:

  1. By compass
  2. By terrain association

Note, that the map does not need to be orientated to take a bearing from a map as the bearing is independent of the direction the map is pointing.

By Compass

  1. Rest the map on level ground.
  2. Rotate the compass bevel to set local magnetic variation (subtract 12.5° for Sydney, NSW area).
    compass-1_eva
  3. Place the compass on the map ensuring the grid lines are parallel with the edge of the compass, and that the top of the compass is point towards the top of the map.
    compass-2_eva
  4. Rotate the map and compass until the north (red) needle is sitting in the orientating arrow on the compass bevel.
    compass-3-2_eva

Handy Tips

  • Remember that compasses work using a very weak magnetic force from the earth. If any objects with a stronger magnetic force are nearby they will distort the compass reading. Make sure that you are not near metal or power lines when using a compass. (e.g. never try using a compass on the hood of a car). Some regions of the earth have high iron content in their rocks making using a compass impossible. The easiest way of telling this is if the compass needle swings erratically, and never points consistently in the same direction, regardless of anything you do!
  • Generally, map orientation only needs to be accurate within a few degrees. Most of the time you can leave the compass with the magnetic variation set inside your map case and orientate the map whilst you are standing.

By Terrain Association
Terrain association is just matching the visible surroundings to the map. It is the most common method that bushwalkers use to orientate a map, but requires a good understanding of how to map read and translate features into real landforms. For this method to work, the user must know their approximate location.
terrain-association

Bushwalkers can determine map orientation by matching contours, comparing vegetation to that depicted on the map, man-made features (shapes of buildings, directions of roads) and hydrography (shape and size of lakes in conjunction with the size and direction of flow of the rivers and streams).

Handy Tip
Generally, bushwalkers use some combination of compass use and terrain association. Usually, they use the compass to get a rough idea of the lay of the land, then fine tune it by matching specific land features to the map. The best way to find out what works for you is to get out there and try!

Thumbing the map How to thumb the map to keep track of where you are

Switching the eyes from the map to the landscape and back again is tiring on the eyes and it’s easy to get disorientated and look at completely the wrong section of map (parallel error).

“Thumbing the map” is a technique used by bushwalkers to trace their location continuously onto the map. It means gripping the map between thumb and hand with the thumb at the exact location of the bushwalk and moving the thumb along the route as they move. In this way, bushwalkers can trace key waypoints {link to key waypoints chapter} as they occur, and know what’s coming up. This is far easier than having to figure out where they are on the map each time they stop.

Some walkers find that folding the map to a convenient size prevents damage and makes it easier to read. Many also use a map case to protect the map from getting damaged. Often map cases come with a neck-strap, allowing the user to carry it on their person and follow the map as they go.
thumbing-the-map

Map Memory and Key Waypoints How to use map memory and key waypoints to stay found

Map memory is about memorizing key features or ‘waypoints’ on a map and ticking them off in your brain as you pass them. It’s about knowing what’s coming up, and if you don’t come across these features, then it quickly triggers a red flag. Think of map memory as ticking off a series of reliable key waypoints.

Key waypoints are those features that are in some way prominent or recognisable. Bushwalkers use key features to orient themselves, know where they are, how far they still have to go, and be able to navigate along the planned route. Memorising the next few waypoints allows the bushwalker to ‘put down the map’ so to speak, or rather at least enjoy the scenery for a bit rather than having their head constantly buried in the map.

A good guide is to memorise the next three major waypoints coming up, and mentally tick them off as you pass them. If anything happens that you weren’t expecting, then you can quickly fix it up. This mental mapping process means that you quickly know where your last ‘known’ point is, so when something doesn’t feel right you notice it straight away, rather than having to figure it out from scratch each time.

The best checkpoints are linear features that cross your route. Use streams, rivers, hard-top roads, ridges, valleys, and railroads, but be aware that some map features are more reliable than others. The next best checkpoints are elevation changes such as hills, depressions and spurs.

Chose waypoints are those that are easy to remember and obvious, but not so common that they are tricky to distinguish.

Examples include:

  1. Land features like knolls, saddles, ridges. Generally very reliable (or as reliable as the data first collected to make the map).
  2. Route features like river crossings. May be unreliable e.g. river crossings can be rainfall dependant.
  3. Man-made features like junctions, road crossings. Again, may change over time or not be reliably marked on the map in the first place.

The number of reliable checkpoints along established on-track routes will vary, but aim to get at least one or two per kilometre. Once you start looking for this detail in the terrain, you’ll find it easier and easier to pick up. Suddenly a boring flat way has subtle ups and downs that you might not have otherwise noticed. Encourage everyone else in the group to keep a lookout for these checkpoints too.

GPS/smartphone devices Using GPS and smartphone devices as navigational tools

GPS devices and mobile smartphones allow the user to pinpoint their location to an accuracy of around 10-20m, often a much greater precision that by map and compass. They communicate with satellites and work well when they have a relatively clear view of the sky. They will not work in enclosed canyons, gorges and caves.

GPS technology allows the user to identify their physical location and plot it back to a topographic map. In a practical sense, often bushwalkers use a GPS to double check their location matches with where they think they are, or to identify recommended campsites, water locations, entrances to canyons, passes through cliff-lines, etc.

GPS users should make sure that their GPS is set to the right datum and projection, and that they understand how to translate the coordinates reported on a GPS unit onto a standard topographic map.