Map and Fieldwork Skills » Map reading basics and grid references

What you'll learn this session

Study time: 30 minutes

How to read and interpret different types of maps
Understanding map symbols and keys
How to use 4-figure and 6-figure grid references
Measuring distance and direction on maps
Understanding scale and calculating real-world distances
Identifying physical and human features on maps

Introduction to Map Reading

Maps are essential tools for geographers. They help us understand where things are located and how different features relate to each other. Whether you're planning a hike, studying settlement patterns, or analysing river systems, knowing how to read maps properly is a crucial skill.

Key Definitions:

Map: A visual representation of an area that shows physical features, cities, roads and other elements.
Ordnance Survey (OS): The national mapping agency for Great Britain that produces detailed maps at different scales.
Scale: The ratio between distance on a map and the corresponding distance on the ground.
Grid reference: A set of numbers used to identify an exact location on a map.

🗺 Types of Maps

Different maps serve different purposes:

Topographic maps: Show the physical features of the land including hills, valleys and rivers
Political maps: Show boundaries between countries, regions and cities
Thematic maps: Display specific themes or subjects (e.g., population density, climate)
OS maps: Detailed maps that show both physical and human features

🔍 Map Symbols and Keys

Maps use symbols to represent features. These symbols are explained in the map key (or legend):

Blue lines/areas = water features (rivers, lakes)
Green areas = vegetation (forests, parks)
Brown contour lines = elevation
Black symbols = human features (buildings, bridges)
Red lines = main roads

Understanding Grid References

OS maps are divided into grid squares to help pinpoint exact locations. Each grid line has a number, creating a coordinate system that works like a game of battleships.

The National Grid System

The UK is covered by a grid of 100km squares, each identified by two letters (e.g., TQ for London). Within these large squares, numbers create a more precise reference system.

🔢 4-Figure Grid References

A 4-figure grid reference identifies a 1km square on the map:

Read the number of the vertical line on the left of the square (the "easting")
Read the number of the horizontal line at the bottom of the square (the "northing")
Combine these numbers to get your 4-figure reference

Remember: "Along the corridor, up the stairs" (east then north)

Example: Grid reference 1945 means the square is between eastings 19 and 20 and northings 45 and 46.

🔢 6-Figure Grid References

A 6-figure grid reference pinpoints a location within a 1km square to 100m accuracy:

Find the 4-figure grid reference of the square
Estimate tenths along from the easting (1-9)
Estimate tenths up from the northing (1-9)
Add these numbers to your 4-figure reference

Example: Grid reference 194456 means the location is 4/10 across square 1945 and 6/10 up.

Top Tip: Grid Reference Mnemonics

Remember these helpful phrases:

"Along the corridor (eastings), up the stairs (northings)" - The order to read grid references
"You go IN through the door before you go UP the stairs" - Eastings come before northings

Measuring Distance and Direction

Maps allow us to measure how far apart things are and determine direction.

📏 Calculating Distance

To measure distance on a map:

Check the map scale (usually shown at the bottom)
Use a ruler to measure the distance in centimetres
Convert this measurement using the scale

Example: If the scale is 1:50,000, then 1cm on the map = 50,000cm (or 0.5km) in real life.

For a quick estimate on 1:50,000 OS maps, 2cm = 1km in real life.

📍 Determining Direction

Direction on maps is shown using compass points:

The top of most maps points north
Grid north (GN) - the direction of the grid lines
True north (TN) - the direction of the North Pole
Magnetic north (MN) - the direction a compass needle points

For iGCSE purposes, we typically use the 8 main compass directions: N, NE, E, SE, S, SW, W, NW.

Understanding Scale

Map scale tells us the relationship between distances on the map and real-world distances.

📊 Ratio Scale

Written as 1:25,000 or 1:50,000

Means 1cm on map = 25,000cm or 50,000cm in reality

Smaller ratio number = more detailed map

📐 Linear Scale

A line marked with distances

Allows direct measurement

Easy to use with a ruler or piece of paper

📑 Statement Scale

Written as "1cm to 0.5km"

Directly states the relationship

Easiest to understand but less common

Reading Contour Lines

Contour lines join points of equal height above sea level, showing the shape of the land:

Close contour lines = steep slope
Widely spaced contour lines = gentle slope
Concentric circles = hill or depression (check the height numbers)
V-shapes pointing uphill = valleys

The contour interval (usually 5m or 10m) tells you the vertical distance between adjacent contour lines.

Case Study Focus: Using OS Maps for Fieldwork

When conducting a river study in the Lake District, students used OS maps to:

Identify suitable sampling locations using 6-figure grid references
Calculate the distance between sampling points
Determine the gradient of the river by reading contour lines
Plan safe access routes to each location
Record land use patterns around the river

This preparation ensured efficient data collection and helped students understand the relationship between the physical landscape and river characteristics.

Practical Map Reading Skills

Developing your map reading skills requires practice. Here are some practical tips:

💡 Map Orientation

To orient a map correctly:

Identify your current location on the map
Rotate the map until features align with what you see
If using a compass, align the map's north with magnetic north

A properly oriented map makes it much easier to navigate and identify features around you.

📋 Identifying Features

Practice identifying both physical and human features:

Physical: Rivers, hills, valleys, coastlines
Human: Settlements, roads, railways, bridges
Land use: Farmland, woodland, urban areas

Look for patterns in how these features relate to each other - this is key to geographical understanding.

Summary

Map reading is a fundamental geographical skill that combines understanding symbols, grid references, scale and landforms. With practice, you'll be able to extract valuable information from maps and use them effectively in your geographical studies and fieldwork.

Remember these key points:

Grid references follow the "along the corridor, up the stairs" rule (eastings then northings)
4-figure references identify a 1km square; 6-figure references pinpoint a location to 100m
Map scale tells you how to convert map distances to real-world distances
Contour lines show the shape of the land - close lines mean steep slopes
Maps use symbols to represent features, which are explained in the key/legend