Ordnance survey maps An introduction

The National Grid Each map has a subzone letter written on it indicating the area on the national grid that the map was taken from. Look at the national grid shown here. Identify the subzone letter for the following places; Dublin Cork Kerry Kilkenny

Ordnance survey maps We use a 4 or 6 figure grid reference system to locate places on ordnance survey maps. To give the location use the grid numbers. Use the rule: You have to go in the door before you go up the stairs. Or remember the word atLas (along top – along side). It may help to draw lines with a ruler straight down and straight across from the point.

Location examples On the area shown give a four figure and a six figure grid reference for the train station. First state the subzone letter. Then go along the top (or bottom), find the number which corresponds with the location of the station. Finally go along the side and find the number which corresponds with the location of the station. G24 18 (four figure) G 24.1 18.4 (six figure – more accurate) We don’t write in the decimal points in our answer. Answer: G 241 184

For you to try Give the grid references for the following points; The post office near the train station. A megalithic tomb A tourist information office A hospital A school The priory Now Check your answers

Answers G243 187 G238 182 G250 190 G236 191 G239 194 G247 188

Direction on Ordnance maps Look at the example given then answer the following; The number 3 is EAST of the number 6. 2 is ___________ of 5. 8 is ___________ of 9. 7 is ___________ of 2 1 is __________ of 4 7 is ___________ of 9 In which direction would you travel when going from; 1 to 4? 5 to 2? 8 to 9? 7 to 1? 7 to 3? 7 to 6? 9 to 3? 6 to 8 NW N NE 8 1 2 3 E W 6 7 5 4 9 SE SW S

Answers North East North South west North West South East South

Scale on Ordnance Survey Maps Scale is the relationship between the distance on a map and its corresponding measurement on the ground. There are three types of scale shown on an ordnance map The linear scale (a black and ruler showing distances in kms). The statement of scale (the written sentence expressing the scale) The Representative Fraction (RF – 1:50000, the ratio of a unit on the map to a unit in reality).

Measuring distances on maps To measure a straight line distance, simply place your ruler down between the 2 points given and measure the distance in cms. The scale of the map will tell you how many cms to Kms. E.G 2 cms = 1km Convert the answer. E.G you measured 6.5cms on the map, this is equal to 3.25kms on the ground.

Measuring a curved line To measure a road, river or any other distance which is not a straight line you can measure the distance by placing a piece of string along it, then measuring the string in cms. OR Using a straight edged piece of paper mark the first point you wish to measure. Keep the straight edge of the paper along the feature you are measuring (river). When you reach a bend mark your piece of paper and the map. Then turn the paper to line up with the next straight portion of the feature. Continue doing this until you reach the finishing point. Then lift your straight edged piece of paper off the map and measure the distance in cms between your starting and finishing mark. Convert cms to kms using your scale

Continue this process until you reach the end point, then measure the distance between start and finish in cms Start Finish

Sketching photographs and maps Always draw a frame similar in shape to that of the map. Never trace a map it must be sketched freehand. Draw the map to half scale. Half the width and the length and use those figures to draw your frame. Show and name only the features that you are specifically asked for. Always outline your sketch with a soft pencil. This allows mistakes to be corrected easily. Outline land use zones with a heavy boundary line to limit the area. Always mark and label each land use area. Use colour only if you have enough time.

Donegal town Mark on and identify 1. The river 2. The street pattern 3. 5 areas of land use

River You may use a grid to help you locate features accurately. Start with easily identifiable features for example rivers or coastline. River

Then sketch in the street pattern of the town

Then add areas of land use. Remember you must label all features or provide a key. Key: Shops Castle Church Factory Housing

Draw a sketch map of the ordnance survey map shown, mark on and identify; The coastline Land below 100m The highest point on the map. One major route focus Two named rivers. Three features indicating the recreational potential of the area

Draw the frame first – same shape as the map not the same size. Draw in some guidelines (as shown) use very light lines these are only a guide for locating features. Draw in the coastline; place dots at important places (headlands and bays) to act as a guide. Shade in the areas below 100m, draw a line that represents the 100m contour. Don’t be over-exact. The use of dots may help here again. Shade the area neatly. Light pencil lines will do you don’t need to use colour. Mark and give an name to the highest point. Mark in the most important route focus and name some routes leading into the town. Draw in two rivers. Use one line for each river, name each river. Mark and name three different recreational areas (e.g one water sports area, a forest for orienteering, a golf course. You may use a key to help you in this case.

For you to try Turn to page 174 in your text book. Draw a sketch map of the area shown. Mark on and identify the following features 3 named settlements 3 named roads An area of mixed forest Haulbowline island The river Lee Cork harbour