OS Maps

OS (Ordnance Survey) Maps are detailed maps that show both natural and human-made features of the landscape. They are commonly used to help people understand and navigate areas by providing a scaled-down view of land. OS maps display features like mountains, rivers, roads, towns, and buildings.

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Scale

Types of Scales

Small-Scale Maps: Show large areas with less detail. These are good for seeing broader regions but lack fine details.

Small-scale map (1:20,000,000)

Large-Scale Maps: Show small areas with much greater detail. These are ideal for closely studying a specific area.

Large-scale map (1:50,000)

Large-scale map (1:8,500)

Understanding Scale

Scale on a map is the ratio between a distance on the map and the actual distance on the ground. For example:

• A scale of 1:50,000 means that 1 cm on the map represents 50,000 cm (or 500 metres) in reality.

Types of Scale Representations:

1. Ratio Scale (e.g., 1:50,000): Shows the relationship as a ratio.
2. Linear Scale: A line divided into units like kilometres or miles, which allows you to measure distances directly on the map.
3. Statement of Scale: A written form that states the scale (e.g., "2 cm to 1 km"), giving an exact measurement guide.

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Measuring Distances on OS Maps

When measuring distances on an OS map, you can measure straight-line distances or curved-line distances depending on the path.

1. Straight Line Distances (As the Crow Flies)

This is the shortest distance between two points on a map.

2. Curved Line Distances (Along Roads or Railways)

For distances along a curved path, such as a road or river, follow these steps:

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Calculating Areas on OS Maps

On OS maps, you can calculate the area of features using grid squares. On a 1:50,000 OS map, each full grid square represents 1 square kilometre (sq km). There are two main methods for calculating area: one for regular (rectangular) shapes and one for irregularly shaped areas.

1. Calculating the Area of Regular (Rectangular) Areas

To find the area of a rectangular section on the map (above):

1. Count the number of grid squares along the base of the area.
2. Count the number of grid squares up the side of the area.
3. Multiply the number of squares across by the number of squares up to get the area in square kilometres.

2. Calculating the Area of Irregularly Shaped Areas

For irregularly shaped areas (like lakes or islands), follow these steps:

1. Tick off and count all grid squares that are at least half-filled by the feature. (see map above)
2. The number of squares gives an approximate area for the feature in square kilometres.

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Directions on OS Maps

Directions on OS maps are shown using compass points. The compass helps to understand which way things are oriented and to give or follow directions accurately.

The Compass Points

The main compass points are:

• N (North)

• E (East)

• S (South)

• W (West) There are also intermediate points for more precise directions, such as:

• NE (Northeast), NW (Northwest)

• SE (Southeast), SW (Southwest)

• Further divisions like NNE (North-Northeast) and SSW (South-Southwest)

How to Use Compass Points on a Map

1. Find the direction you need to go or identify by lining it up with the compass.
2. Use the compass rose (the compass symbol) on the map to determine directions between places.

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Locating Places on OS Maps: The National Grid

The National Grid is a system used on OS maps to help locate specific places. It divides the map into lettered sub-zones and uses grid references to pinpoint locations.

Understanding Sub-Zones

• Each OS map has a tiny map of Ireland with lettered sub-zones marked (like F, G, H).

• The map's sub-zone letter (in blue) indicates which part of Ireland it covers.

  

• If a map spans more than one sub-zone, it will display multiple letters.

Eastings and Northings

Each sub-zone is further divided into a grid using blue lines:

• Eastings: These are the vertical lines that run up and down the map. They increase in value as you move eastward (right).
• Northings: These are the horizontal lines that run across the map. They increase in value as you move northward (up).
• Both Eastings and Northings are numbered from 00 to 99.

Using Grid References

Grid references help you locate exact places on the map. There are two main types:

1. Four-Figure Grid References: Used to identify a specific grid square. For example, "28 19" locates a square on the map.
2. Six-Figure Grid References: Provides a more precise location within a grid square by dividing it into smaller sections. For example, "283 192" gives a detailed point within the square.

How to Get a Four-Figure Grid Reference

A four-figure grid reference helps you locate a specific grid square on an OS map. It provides a general location of features within that square.

How to Get a Six-Figure Grid Reference

A six-figure grid reference gives an exact location within a grid square on an OS map. It is more precise than a four-figure grid reference, allowing you to pinpoint a feature more accurately.

Tips for Using Six-Figure Grid References

1. Write down the first three figures (eg. 996) for the Easting and the last three figures (eg. 173) for the Northing.
2. Draw lines from these points to locate the exact spot where they intersect on the map.

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Symbols on OS Maps

Symbols on OS maps are small images or icons that represent different features on the map, making it easier to identify landmarks, buildings, and natural features without using too much text. Each symbol has a specific meaning and is explained in the map key or legend, usually found at the base of the map.

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Showing Altitude (Height) on OS Maps

Altitude, or height above sea level, is shown on OS maps in metres. Knowing the altitude helps you understand the landscape's elevation and terrain. OS maps represent height in four main ways:

1. Triangulation Stations - also known as Trigonometrical Point or Trig Point

• Marked by black triangles on the map with a number beside them indicating the height.
• These show the altitude of significant mountain peaks or high points.

2. Spot Heights

• Represented by black dots with the altitude written next to them.
• Spot heights indicate the elevation of specific points or places, giving precise measurements of these locations.

3. Contour Lines

• Contours are lines that connect points of equal height across a map.
• They indicate the shape of the land:
• Close contour lines mean steep terrain.
• Widely spaced contours mean gentle slopes or flat areas.
• Some contour lines have the altitude marked on them for easy reference.

4. Colour Coding

• Colour shading shows areas of different elevations:
• Land below 200 metres is shown in shades of green.
• Higher elevations are shown in brown, with darker shades indicating greater height.

Showing Slope on OS Maps

The slope or steepness of the land on OS maps is indicated by the spacing of contour lines. Contours connect points of equal height, and the distance between them helps to show how steep or flat the land is.

Types of Slopes:

1. Flat Land:

• No contour lines are present, indicating flat terrain with no significant changes in elevation.

2. Gentle Slopes:

• Contour lines are widely spaced, showing a gradual incline or decline in elevation.

3. Steep Slopes:

• Contour lines are closely packed together, indicating a rapid change in height over a short distance.

4. Cliffs:

• Contour lines merge or appear almost on top of each other, showing a vertical or nearly vertical drop.

Types of Slope on OS Maps

OS maps use contour lines to show different types of slopes, which reveal how the land rises and falls.

5. Even Slope:

• Contour lines are evenly spaced throughout, showing a uniform incline or decline.
• Example: A steady, even slope with no changes in steepness.

6. Concave Slope:

• Widely spaced contour lines at the base (gentle slope) and closely spaced at the top (steeper slope).
• Indicates that the slope gets steeper as you go up.

7. Convex Slope:

• Closely spaced contour lines at the base (steeper slope) and widely spaced at the top (gentle slope).
• Shows a slope that is steep at the bottom and becomes gentler towards the top.

8. Compound Slope:

• A combination of both concave and convex slopes.
• Part of the slope is concave (gentle at the bottom, steep at the top), and part is convex (steep at the bottom, gentle at the top).

Cross-Sections on OS Maps

A cross-section (or profile) is a side view of the landscape along a specific line on a map. Cross-sections help show the height, slope, and shape of the land, providing a clear visual of the terrain's elevation changes.

How Cross-Sections Work

• Cross-sections are drawn by taking a line (e.g., A–B) across the map and then creating a profile of the landscape along that line.
• This profile is usually drawn on graph paper, showing how the land rises and falls along the line.
• Cross-sections can be used to compare the steepness of slopes, identify valleys or ridges, and understand the overall shape of the land. Example:

Drawing Sketch Maps

How to Draw a Sketch Map

A sketch map is a simplified drawing of an area, showing only the most important features. Here are the steps to create one:

Tips:

• Keep the sketch simple and clear.
• Use the segments as a guide to keep everything in the correct location.
• Label key features neatly to make the map easy to understand.
• Normally you do not need to colour your sketch map.

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Relief on OS Maps

Relief refers to the shape and height of the land surface, including features like hills, mountains, and valleys. Relief helps us understand the physical landscape by showing variations in elevation and landforms.

Key Relief Features on OS Maps:

1. Upland:

• Land that is higher than 200 metres above sea level.
• Shown in yellow or brown on OS maps.

2. Lowland:

• Land that is lower than 200 metres above sea level.
• Shown in green on OS maps, indicating flat or gently rolling land.

3. Mountain:

• A steep-sided landform that rises above 400 metres.
• Mountains are usually indicated by closely spaced contour lines.

4. Hill:

• A raised area of land with steep sides, but lower than 400 metres.
• Represented by contour lines that form circular or oval shapes, with the height decreasing outward.

5. Ridge:

• A long, narrow upland area with steep sides.
• Represented by a series of contours that follow the shape of the ridge.

6. Valley:

• A long and narrow depression, often occupied by a river.
• Contour lines create a "V" or "U" shape that points upstream, indicating the valley's direction.

Understanding Relief on OS Maps

• Colour Coding: Different colours help to show elevation (e.g., green for lowland, brown for upland).
• Contour Lines: Close contour lines indicate steep slopes, while widely spaced contours show gentle slopes or flat land.

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Water Features and Drainage on OS Maps

OS maps show various water features using specific symbols, which help identify lakes, rivers, canals, marshes, and beaches. Understanding these symbols and drainage patterns is essential for interpreting the flow and collection of water in an area.

Key Water Features Symbols

Understanding Drainage

Drainage refers to how water flows and collects on the land. It is crucial for understanding areas that are well-drained versus those that are badly drained.

• Well-Drained Areas:

  • Generally suitable for various land uses due to low flood risk.

• Badly Drained Areas:

  

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Transport and Settlements on OS Maps

OS maps show important information about transport routes and settlements in an area, helping us understand how people travel and where they live.

Transport

• Roads: Different types of roads are shown with distinct symbols.

  • Motorways (e.g., M1) are large, high-speed roads.
  • National Primary Roads (e.g., N11) are major roads connecting key towns and cities.
  • National Secondary Roads (e.g., N71) and Regional Roads (R roads) are smaller but still important for connecting local areas.

• Railways: Rail lines are shown with symbols for railway stations and level crossings.

  

• Other Transport: OS maps may also show transport by air, sea, and waterways (rivers and canals).

Routeways and Landscape:

• Relief (height) and drainage (water flow) influence where roads and paths are built.

  • Highlands (steep areas) have fewer roads due to difficult building conditions.

  • Roads often follow valleys or gaps in hills to avoid steep slopes.

    

  • Roads are built close to, but away from, rivers to avoid flood risks and allow for easy bridging points.

Settlements

A settlement is where people live, and it can vary from small rural areas to large urban towns and cities. OS maps show different types of settlements:

• Former (Historic) Settlements: Indicated by symbols for antiquities such as ancient forts, castles, ring forts, and burial sites. These historic sites are marked in red and give clues about where people lived in the past.
• Rural Settlements: Include isolated houses, farms, and small villages.
• Urban Settlements: Represent larger towns and cities, which are shown with clustered buildings and named streets.

Antiquities and Religious Sites:

• OS maps often highlight historical and religious sites, such as churches, abbeys, castles, and holy wells.
• These are marked with specific symbols and often appear in rural areas, indicating significant historic and cultural sites.

Rural Settlement and Settlement Patterns on OS Maps

Rural settlements refer to areas where people live in the countryside. Various physical factors influence the density and location of rural settlements, and these settlements often form different patterns across the landscape.

Factors Affecting Rural Settlement Density and Location

1. Altitude:

• Most people live on land below 200 metres, as it's usually warmer and less exposed to harsh winds.
• Higher land is often too cold or windy for settlement, and is coloured green on OS maps.

2. Slope:

• People prefer to live on flat or gently sloping land where it's easier to build houses and roads.
• Steep slopes are more difficult to develop and are often avoided.

3. Aspect:

• The aspect, or direction a slope faces, affects warmth. South-facing slopes receive more sunlight and are generally warmer, making them more attractive for settlement.

4. Drainage:

• Well-drained land is more suitable for settlement, as poorly drained areas may be prone to flooding.
• In the past, settlements were often located near rivers, as they provided a reliable water source.

Rural Settlement Patterns

Rural settlements can be organised in several distinct patterns, each reflecting how buildings are distributed across the landscape:

5. Dispersed Settlement:

• Buildings are spread out across the countryside.
• Typically found in farming areas, with isolated farmhouses surrounded by fields.

6. Linear (or Ribbon) Settlement:

• Buildings are arranged in a line, often along a road, river, or the base of a hill.
• Common along coastlines or valleys, where development follows a natural routeway.

7. Nucleated Settlement:

• Buildings are clustered together, often at crossroads or the meeting point of roads.
• These settlements can form small villages or towns, with homes and other buildings grouped around a central point.

The Development and Location of Towns

Towns develop in specific locations due to factors that make them suitable for urban settlement. Key reasons why towns form and grow include:

• Flat or Gently Sloping Lowlands:
  • Easier to build roads, buildings, and infrastructure on flat land.
  • These areas often become market centres where produce from surrounding agricultural land can be traded.
• Transport Routes:
  • Towns often develop where different roads, railways, or waterways meet. Such locations facilitate trade and allow people to gather, promoting economic growth.
• Bridging Points:
  • Where a river is bridged, roads tend to meet, making it a strategic location for a town.
  • Bridges near the coast are important, as they provide access to trade routes and water supplies.
• Coastal Locations:
  • Many towns form along the coast due to access to the sea, which supports fishing, trade, and tourism.

Services/Functions and the Development of Towns

Towns develop because of the services or functions they provide for the people. Most have several functions. Many can be identified on OS maps:

Function	Explanation	Clues on 1:50,000 OS Maps
Defence	Some towns began as defence sites with castles or towers, which were easy to defend.	Castles or towers in or near the town
Church	Many towns grew around religious sites like monasteries or abbeys, providing education, health, and social services.	Monasteries, abbeys, priories, or old churches near the town
Market	Served as a place for trading agricultural produce from surrounding countryside.	Located in well-drained lowlands near fertile farmland
Port	Ports facilitate trade (cargo ports) and fishing. Cargo ports are larger, while fishing ports are smaller.	Deep bays, estuaries, piers, docks, lighthouses, or beacons
Tourist Resort	Developed due to attractions for tourism, providing recreational services.	Scenic: mountains, lakes, woodlands. Coastal: beaches, dunes, cliffs. Cultural: caravan parks, youth hostels, golf courses, tourist information centres
Manufacturing	Towns with factories or industrial estates, though not always visible on OS maps.	Industrial estate symbol (Ind Est)
Other Services	Provide a range of general services, like schools, hospitals, shops, and recreational facilities.	Schools (Sch), Colleges (Coll), Convent (Conv), Garda Station (police), Hospital (Hosp), Fire Station (Fire Stn), Parking (P)

Understanding Place Names in Ireland

Here are some common Irish words found in place names and their meanings:

Word	Meaning	Word	Meaning
Sliabh (Slieve/Sleeve)	Mountain	Lios (Lis)	Fort
Cnoc (Knock)	Hill	Dún (Doon)	Ancient fort
Drom (Drum)	Ridge	Rath	Ring fort
Gleann (Glen)	Valley/Glen	Caher	Stone fort
Abhainn (Owen)	River	...mór (more)	Large
Áth	Crossing point of a river	...beag (beg)	Small
Inis (Inish/Inch)	Island	...ín (een)	Little
Carraig (Carrick)	Rock	...ard	High
Baile (Bally)	Small settlement	...dubh (duff)	Black
Teampall (Temple)	Church	...buí (boy)	Yellow
Cill (Kil)	Church	...sean (shan/shane)	Old
Ros	Wood

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Recreation, Tourism and Maps

Physical features = blue labels

Human features = red labels

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Locating Large Buildings on OS Maps

When choosing a location for large buildings like a factory, hotel or leisure centre, or school, several factors need to be considered to ensure that the site is suitable for its intended purpose.

Here are the key factors:

1. Site

• Factory: Needs a large, empty site for buildings, parking, and potential future expansion.
• Hotel/Leisure Centre: Prefers a flat, accessible area, which is easier and cheaper to develop.
• School: Also benefits from a flat site, which makes building and expansion easier.

2. Transport

• Factory: Requires good roads to transport raw materials, products, and workers. Railway stations and airports nearby can assist with importing/exporting goods and moving staff.
• Hotel/Leisure Centre: Needs good roads for customer access and a nearby railway station may attract more visitors.
• School: Needs good roads to allow easy access for students and teachers by car or bus. A nearby railway station might also be useful.

3. Proximity to a Town

• Factory: A nearby town can provide workers for the factory. However, placing a factory within a town might create issues like noise pollution or traffic congestion.
• Hotel/Leisure Centre: Proximity to a town provides customers for the hotel or leisure centre.
• School: A nearby town provides students and can offer accommodation for some teachers.

4. Other Factors

• Factory: Factories in towns may have access to urban services like sewerage and water. Factories are often placed in industrial estates, where they can benefit from proximity to other factories (e.g., sharing resources or materials).
• Hotel/Leisure Centre: Access to town services can benefit the centre.
• School: Less need for linkages with other industries but benefits from urban services and proximity to residential areas.

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Street Maps

Street maps are detailed maps of urban areas, showing streets, buildings, and various services in a specific area. They are often large-scale maps, meaning they show a lot of detail over a small area, which is useful for navigation within cities.

Locating Places

• Street maps often use a letter-and-number grid system to help locate specific places. For example, a location in grid G1 is found within the 'G' section along the top and the '1' section along the side.

Symbols on Street Maps

• Like other maps, street maps have symbols to represent different services and functions available in the area. Some common symbols include:
  • Hospital: Often shown with an 'H' symbol.
  • Bus/Rail Stations: Represented by a bus or train icon.
  • Public Buildings, Parks, and Recreation: These have unique symbols for easy identification.
• Refer to the legend or key on the map to interpret these symbols.

Planned and Unplanned Urban Areas

Street maps can show whether an area is planned or unplanned:

• Planned Areas:
  • Typically have straight streets that intersect at right angles.
  • These create a grid-like pattern of rectangular building blocks.
  • May include square or rectangular parks and recreational areas.
• Unplanned Areas:
  • Usually feature older, winding streets that meet at random angles.
  • These areas often developed over time without a formal layout, creating an irregular street pattern.