grid & area references
DESCRIPTION
Grid & Area References. It can be difficult to find places or features easily on a map. So far we have learnt that to find places on a street directory we use an alpha-numeric grid (e.g. B7) - PowerPoint PPT PresentationTRANSCRIPT
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Grid & Area ReferencesGrid & Area References• It can be difficult to find places or features easily on a map.
• So far we have learnt that to find places on a street directory we use an alpha-numeric grid (e.g. B7)
• We also know that to find places on a larger scale, such as a world map we use Latitude & Longitude coordinates to help us find what we are looking for.
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Topographic maps are large scale and we use these for Area and Grid references
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So how do we locate features on a Topographic map?
• We can locate places easily on a topographic map by using the maps gridlines.
• On a topographic map the vertical ( )lines are
called eastings because they increase in value as we move eastward.
• The horizontal ( ) lines are called northings because they increase in value as we move northwards.
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Eastings
Northings
N
1818
1717
1616
1515
2222 2323 2424 2525 2626 2727
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Area Reference
• Features such as a small lake, quarry or village are usually located by means of an Area Reference (AR)
• To find the (AR) of a feature we use the coordinate in the lower left-hand corner of the grid square in which the feature is located.
• You always read the easting first then the northing. (hint to remember E comes before N in the alphabet)
• An area reference always has 4 figures
EXAMPLE: AR3363
easting northing
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Eastings
Northings
N
1818
1717
1616
1515
2222 2323 2424 2525 2626 2727
The Area Reference of the house is:
AR2317
Remember with (AR) you use the bottom left hand corner
What is the (AR) for:
The plane:
AR2215
The boy:
AR2316
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Grid References• We can locate relatively small and more specific features
on map by using Grid Reference (GR). • (GR) locates the exact point on the grid.
• Unlike (AR), Grid Reference uses 6 figures.
-The first two numbers of each coordinate refers to the eastings and northings that surround the map.
- The third number needed to complete each coordinate is obtained by dividing each easting and northing into tenths.
Example: GR335638
easting northing
Dividing the easting and northing into tenths
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EastingsNorthing
N
1818
1717
1616
1515
2222 2323 2424 2525 2626 2727
What is the grid reference (GR) for the ball in which the boy is about to catch?
Answer:
GR238169
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Interactives
• http://mapzone.ordnancesurvey.co.uk/mapzone/PagesHomeworkHelp/maptivity/gridreferences/
• http://geographyfieldwork.com/TestGridIntro.htm
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CLASS EXERCISE
Give the (AR) for the following features:
1. Church;
2. Village Hall;
3. Grove farm;
4. The dairy farm;
5. The town of Little Plumpton;
6. The entire (AR)’s for Gibbet Wood;
7. The (AR)’s that Dale Road passes through;
8. The approximate (GR) of Grove farm.
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• http://www.mape.org.uk/startower/maps/resources/map1.htm
• http://www.mape.org.uk/startower/maps/resources/map1b.htm