GLOSSARY

Here is a list of all the geographic terms and vocabularies used in this blog, with their corresponding definitions.

A

Altitude: This refers to the vertical position of a point or an object that is above the earth’s surface, above the mean sea level. (Compare with Elevation)
A.M.S.L: Abbreviation for ‘Above Mean Sea Level’.

B

Benchmark: This is a surveyor’s mark, which is made on a stationary object on the ground like a wall, a pillar, a rock or a building, whose position and elevation have been previously determined/ are known. In surveying, a benchmark is usually used as a reference point from which the elevation of other objects on the ground are determined. BM.

C

Centripetal drainage pattern: in this drainage pattern, streams flow from different direction and converge at the same end-point, which is generally a depression or a basin.
Contouring: This is an act of using contour lines when representing the relief of an area on the map. 
Contour interval (or vertical interval): This is the difference in height between any two successive contours on map.
Contour lines: These are the lines drawn on the map connecting all points on the earth’s surface with equal elevations above the mean sea level.

D

Dendritic drainage pattern: in this drainage pattern, the tributaries join the main river at acute angles, resembling the shape of a tree with its branches.
Depth: This is the vertical position of points/objects below the mean sea level. (Compare with elevation)
A drainage pattern (or a river system): This is a pattern achieved by a network of river channels and tributaries in a particular drainage basin. Common drainage patterns include centripetal, radial, trellis and parallel.

E

Elevation: This refers to the vertical position, above the mean sea level, of a point/an object that is on the earth’s surface. (Compare with altitude and with depth)
Elevation points: These are miscellaneous dots and marks used to show the elevation of various points on the map. Trigonometric points, spot heights and benchmarks are the three common types of elevation points used on the map.

F

Form lines: refer to supplementary contour lines.

G

Gradient: This is the average rate, at which the ground slopes. It measures the average steepness of the slope of a piece of land.

H

Hachures (also hachure lines): These are short broken lines, which vary in thickness and length, used on a map to indicate the direction and steepness of the slope.
Hachuring: This is an act of using hachures when representing the relief of an area on the map.
Horizontal Equivalent: This is the actual ground distance between any two points on the map.
Hypsometric coloring: refer to Layer tinting.
Hypsometric maps: These maps use the system of colors to represent relief of a landscape.

I

Index contour lines: These are the contour lines, which are usually labelled with their elevation on the map, and sometimes bolded a little bit heavier than the rest.
Intermediate contour lines: these are the contour lines that usually fall in-between the index contour lines. They are finer than index contours and do not have their elevations labelled on them.

L

Layer tinting (also called layer coloring or hypsometric coloring): This is a method used to represents relief of an area on maps by using various shades of colors. All areas on map with relatively similar elevations are represented by the same shade of color.

P

Parallel drainage pattern: In this drainage pattern, several rivers flow in the same direction, usually with few tributaries.

R

Radial drainage pattern (also centrifugal drainage pattern): In this drainage pattern, streams diverge from a central high point towards different direction.
Rectangular drainage pattern: This drainage pattern is characterized with many right-angle bends in both the main streams and their tributaries.
Relief (or terrain): This is the physical configuration or appearance of the land surface in terms of shape, orientation, size, elevation and slope.
Relief shading: This is a method that is used to present the relief of an area on a map through light-shadow effect whereby shades of various intensity are used on the map to indicate the steepness of the slope.

S

Slope: This is an inclined ground surface, which forms an angle with any horizontal plane of the earth’s surface.
Spot heights (or spot elevations): These are convectional dots used to show the exact elevation of points on the map. On the map, Spot heights are depicted by using a dot together with a number that indicates the exact elevation of the given point.
Supplementary contour lines (or form lines): These contour lines appear on the map as dashed or thin continuous lines with no representative value of elevation on them.  They are used when the normal contour interval is sometimes too large to represent a significant change in elevation, such as on level terrain.

T

Trellis drainage pattern: In this drainage pattern, short subsequent tributaries join the main stream at right almost angles.
Trigonometric points: These are convectional small triangles used on maps to show the exact elevation of the highest point in a given area and to indicate the presence of a trigonometric station on the ground.

V

Vertical Increase (also Vertical Rise): This is the difference in elevation between any two points on the map.
Vertical interval: refer to contour interval.