Easting and Northings
With reference to a point, the line or axes running from north to south are known as Eastings. Eastings indicate the distance east of the referenced point. Similarly, the line running from east to west are known as Northings because they indicate the distance north of the referenced point.
Contour lines are imaginary lines joining places of equal height above mean sea level. Contour lines make it possible to read areas of hills, valleys and level land on a map.
Contour lines that are very close together on a map indicate very steep slope. When these lines are far apart on a map, it indicate gentle slope. The absence of contour lines on the map indicate very flat land.
The top of a plateau is flat, characterized by very few contours while the sides are often steep which is characterized by contours close together.
Bench marks are basically fixed heights above mean sea level. They are indicated by the sign
Bench marks are chiseled into stonework or walls of buildings.
There are two types of photographic maps, Vertical; which is picture taken from an airplane and looking down vertically (90 degrees) and Oblique; taken at any position except vertical.
Scales can be represented in two ways on maps;
- As a statement scale such as ½ inch to 1 mile or
- Representative fraction (R.F), for example, 1: 253440, which means 1 inch to 253440 inches. In R.F, the scale unit and what it represents are the same.
Gradient is the means of defining the slope of a land. It is calculated by measuring the horizontal distance between two points and dividing by vertical difference in height between the 2 points.
Can be defined as angular bearing measured from north in a clockwise direction.
This is defined as the activity of man on the landscape for building settlement, farming, making routes, etc. to achieve the best results, man is usually guided by natural conditions of land and terrain.