Glossary

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Glossary of terms used in this navigation tutorial

 Term Meaning Bearing A direction of travel. Whenever you are walking in a straight line, you are following a bearing. Bearings are given as an angle in degrees clockwise from north. A bearing may be a grid bearing or a magnetic bearing. Cliff Vertical or near vertical ground. Usually in the form of steep rock. Contour interval The vertical displacement between one contour line and the next. This will be a specified amount (in feet or metres) for each map. Contour line A line on a topographic map representing land of a specified elevation. It is a line that joins points of an equal elevation. Depression An area of ground that is surrounded in all directions by higher ground. For example, volcanic craters and limestone sink holes. Easting A grid line running north-south on the map. Grid Bearing A bearing relative to grid north. Given as an angle east (clockwise) from grid north. Grid Line There is a matrix or grid on each topographic map that is aligned to grid north. A grid line is one of the lines on this grid and you use this in conjunction with your compass when navigating. Grid North This is the direction of the north-south running grid lines on your map. All topographic maps used by bushwalkers have a grid superimposed upon them, and this grid is aligned to grid north. Grid north is slightly different to true north because of the distortion caused by the curvature of the Earth being represented on a flat map sheet. Grid Reference A pair of numbers that gives the coordinates of a position on a map according to the map's grid. The first number in the pair denotes the position on an east-west axis. The second number in the pair denotes the position on a north-south axis. In navigation by map and compass grid references are normally containto 6 figures (a pair of 3 numbers) which on metric maps is accurate to 1 hectare (100m x 100m). Gully A small sloping watercourse. A small valley with a sloping profile. Knoll A small hill. Maybe a bump on a ridge. Magnetic Bearing A bearing relative to magnetic north. Given as an angle east (clockwise) from magnetic north. Magnetic North This is the direction of the Earth's magnetic north pole, which is the axis along which the Earth's magnetic field is aligned. It is not the same as the Earth's axis of rotation or the Earth's lines of longitude. The magnetic north pole is a region in the Canadian arctic. Magnetic North is important to navigation because it is where your compass needle points. Non-perennial A non-perennial stream is one which flows only at certain times of year or only after rain. Northing A grid line running east-west on the map. Open forest Forest in which the tree canopy is open. That is, there are enough gaps between the trees that direct sunlight can reach the forest floor. There is not much overlapping of tree branches so there are substantial gaps in the leaf canopy. Perennial A perennial stream or watercourse is one which normally flows or at least contains water all year round. Rainforest Forest in which the tree canopy is closed. Little direct sunlight reaches the forest floor. Branches of trees overlap eachother creating an unbroken leaf canopy. Resection The name given to the technique of working out your position by taking bearings of 3 different features whose location is known. Your location is the intersection of these 3 bearings. See Section 10.5. Ridge A range of hills or mountains. The high ground that divides one valley from the next. Saddle A low point on a ridge. The ridge rises on both sides of a saddle. Scale The ratio that is used to convert distances on the map to distances on the ground. Sink hole A small depression or area of sunken ground that is often found in limestone areas. Sink holes may be an indication of underground limestone caves in the near vicinity. Spur A sloping ridge. A ridge that rises from a valley or other low ground, or descends from a peak or range. Topographic map Any map that shows the elevation of of landforms. Triangulation Another name for a resection True North This is the direction of the true north pole, which is the Earth's axis of rotation. It is the direction of the Earth's lines of longitude.True north is not normally relevant when navigating.

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