Welcome to Globes, Maps, and Atlases!
Have you ever used an app on your phone to find your way to a friend's house, or looked at a globe spinning in your classroom? Geographers use globes, maps, and atlases as essential tools to explore and understand the world around us. In this chapter, you will discover how to pinpoint any place on Earth, crack the secret code of map symbols, master 4-figure and 6-figure grid references, and read the shape of the land. Don't worry if this seems a bit tricky at first—we will break everything down step-by-step!
---Part 1: Globes and the World Grid
Because the Earth is a three-dimensional sphere, the most accurate way to show the whole planet is on a spherical model called a globe. To help us find exact locations on this sphere, geographers draw an imaginary grid of lines over it: latitude and longitude.
1. Lines of Latitude
• What they are: Imaginary horizontal lines that wrap around the Earth like belts.
• What they measure: They measure distance North or South of the Equator.
• The Equator: This is the main line of latitude at \(0^\circ\). It splits the Earth right down the middle into two halves: the Northern Hemisphere and the Southern Hemisphere.
• Key values: The North Pole is at \(90^\circ\text{N}\) and the South Pole is at \(90^\circ\text{S}\).
• Memory Trick: Remember that "Lat is flat"! Lines of latitude lie flat and go across from side to side.
2. Lines of Longitude
• What they are: Imaginary vertical lines that run from the top of the Earth to the bottom (connecting the North Pole and the South Pole).
• What they measure: They measure distance East or West of the Prime Meridian.
• The Prime Meridian: This is the starting line of longitude at \(0^\circ\). It passes straight through Greenwich in London, England.
• Memory Trick: Longitude lines are "long" lines reaching from the top pole all the way to the bottom pole.
3. Longitude and Time Zones
Did you know that the Earth rotates once every 24 hours? Because of this, time changes as you travel East or West.
• The Earth is divided into 24 time zones based on lines of longitude.
• Each time zone is approximately \(15^\circ\) of longitude wide.
Key Takeaway for Part 1: Latitude lines are flat (North/South of the Equator at \(0^\circ\)), and Longitude lines are vertical (East/West of the Prime Meridian at \(0^\circ\)). Together, they form a world grid that gives every place on Earth a unique address!
---Part 2: Understanding Direction and Scale on Maps
1. The 8 Points of the Compass
To navigate using a map, you need to know which direction you are facing. Geographers use an 8-point compass rose:
• North (N) — pointing straight up
• North-East (NE) — halfway between North and East
• East (E) — pointing right
• South-East (SE) — halfway between South and East
• South (S) — pointing straight down
• South-West (SW) — halfway between South and West
• West (W) — pointing left
• North-West (NW) — halfway between North and West
• Memory Trick: Moving clockwise from the top: Naughty Elephants Squirt Water (North, East, South, West).
2. Map Scales: Bringing the Real World onto Paper
A map cannot be the same size as the real world, so it is shrunk down using a scale. In the UK, the standard maps used are Ordnance Survey (OS) maps. You will commonly encounter two main types:
• \(1:25,000\) (Explorer Maps):
On this map, \(4\text{cm}\) on the map equals \(1\text{km}\) on the actual ground. These maps show great detail and are used by walkers and cyclists.
• \(1:50,000\) (Landranger Maps):
On this map, \(2\text{cm}\) on the map equals \(1\text{km}\) on the actual ground. These maps cover a larger area and are used for driving and general navigation.
Common Mistake Alert: Large Scale vs Small Scale
This is a classic exam trap! Don't let it catch you out:
• A large-scale map (such as \(1:1,250\)) shows a small area of ground, but with a large amount of detail (like individual houses or gardens).
• A small-scale map (such as \(1:250,000\)) shows a large area of ground (like a whole county or country), but with a small amount of detail.
Key Takeaway for Part 2: An 8-point compass gives direction. Scale tells you how much the real world has been shrunk down (\(4\text{cm} = 1\text{km}\) on a \(1:25,000\) map; \(2\text{cm} = 1\text{km}\) on a \(1:50,000\) map).
---Part 3: Mastering OS Grid References
Ordnance Survey maps are covered in a blue grid. The squares help us locate features quickly and accurately.
1. Eastings and Northings
• Eastings: These are the vertical lines on the map. Their numbers increase as you travel towards the East (to the right).
• Northings: These are the horizontal lines on the map. Their numbers increase as you travel towards the North (upwards).
• The Golden Rule: Always give Eastings first, then Northings! Remember: "Along the corridor (Eastings), then up the stairs (Northings)."
2. How to Give a 4-Figure Grid Reference
A 4-figure grid reference identifies a whole \(1\text{km} \times 1\text{km}\) grid square.
Step-by-Step Guide:
1. Find the square you want to identify.
2. Look at the bottom-left corner of that square.
3. Read the 2-digit number of the vertical line (the Easting) along the corridor.
4. Read the 2-digit number of the horizontal line (the Northing) up the stairs.
5. Put the numbers together! (For example: Easting 24 and Northing 35 give the 4-figure grid reference 2435).
3. How to Give a 6-Figure Grid Reference
A 6-figure grid reference is much more precise. It pinpoints a specific \(100\text{m} \times 100\text{m}\) point inside that grid square.
Step-by-Step Guide:
1. Find the 4-figure grid square (e.g., 24 for the Easting, 35 for the Northing).
2. Imagine the grid square is split into 10 smaller tenths from left to right (0 to 9). Estimate how many tenths across your point is (e.g., 3 tenths). Add this digit to your Easting: 243.
3. Now imagine the square is split into 10 smaller tenths from bottom to top (0 to 9). Estimate how many tenths up your point is (e.g., 7 tenths). Add this digit to your Northing: 357.
4. Combine the two 3-digit sets: 243357.
Key Takeaway for Part 3: Always go along the corridor (Eastings) before going up the stairs (Northings). A 4-figure reference points to a \(1\text{km} \times 1\text{km}\) square; a 6-figure reference points to an exact \(100\text{m} \times 100\text{m}\) location.
---Part 4: Representing the Landscape and Relief
Maps are flat sheets of paper, but the real world is full of hills, valleys, and mountains. Relief is the word geographers use to describe the shape and height of the land. OS maps show relief in three main ways:
1. Contour Lines
• What they are: Thin orange or brown lines drawn on a map that join together places of equal height above sea level.
• Contour Interval: On standard OS maps, contour lines are usually drawn at regular intervals of \(5\text{m}\) or \(10\text{m}\).
• How to read slope steepness:
- When contour lines are close together, the land is steep (like a cliff or steep hill).
- When contour lines are far apart, the land is flat or gently sloping.
2. Spot Heights
• A spot height shows the exact height of a specific point above sea level.
• It is shown on an OS map as a black dot with a number next to it (for example, a dot with \(142\) next to it means that exact spot is \(142\text{m}\) above sea level).
3. Triangulation Pillars (Trig Points)
• A triangulation pillar (or trig point) is a real, physical concrete pillar placed at the top of hills and mountains that was used by surveyors to measure heights across the country.
• On an OS map, it is shown as a small blue triangle (often with the exact height number written alongside it).
Key Takeaway for Part 4: Relief means the shape and height of the land. Contour lines join equal heights (close lines = steep; wide lines = gentle). Spot heights and trig points show exact heights at specific locations.
---Part 5: Map Symbols and the Map Legend
Maps do not have enough space to write words for everything like rivers, car parks, or churches. Instead, geographers use map symbols.
• The Map Legend (or Key): This is an essential guide printed on the side of every OS map that explains what every symbol, line, and colour stands for.
• Examples of standard OS symbols:
- A blue line represents a river.
- A blue letter 'P' represents parking.
- Different symbols and letters represent features like footpaths, viewpoints, and places of worship.
• Top Tip: You never need to guess what a symbol means—simply check the map key!
Quick Review: Top Pitfalls to Avoid in Tests
Check your understanding against these four common mistakes:
1. Putting Northings before Eastings: Always read the bottom horizontal axis first (Easting), then the vertical axis (Northing). Along the corridor, then up the stairs!
2. Confusing Latitude and Longitude: Remember, Lat is flat (horizontal lines measuring North/South). Longitude lines are vertical (measuring East/West).
3. Misreading Contour Spacing: Lines close together mean a steep hill, not a flat area.
4. Mixing up Map Scales: A large-scale map shows a smaller area with lots of detail (like \(1:25,000\)). A small-scale map shows a large area with less detail.