Arago: Exhibits

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Relief

Relief is the representation of all portions of the earth above the sea which have a three-dimensional form, sometimes referred to as ‘the lay of the land.’ Early cartographers were unable to symbolize relief accurately due to lack of familiarity with land forms. When surveying became a precise science, this shortcoming no longer prevailed and it then became feasible to portrait the earth’s terrain accurately on a map. Methods of showing topography have varied over the centuries. During the 16th and 17th centuries, mountains were show in profile, sometimes called ‘molehill’ style. Later, hachuring was used to delineate the terrain effectively. With better technology in the 19th and 20th centuries, contouring, hyposometric, shaded relief, and pictorial/land form styles became feasible, providing map readers new realms of accuracy and detail.

Profile (molehill) relief was the method used by cartographers of the 16th and 17th centuries. Mountains were shown in profile and placed to show where mountain ranges existed. This method could only indicate the location of mountains but could not accurately show relief in ‘plan’ as modern maps do.

Hachures are short lines drawn down the slope in the direction of the steepest gradient; conventionally, they are drawn more closely together where the slope is steeper, and can be made heavier on the southeast sides of land forms to give an increased appearance of relief. The chief disadvantages of hachuring are (1) the lack of absolute information for which numerous spot-heights have to be inserted; (2) the difficulty of drawing hachures in the field; and (3) the problem of distinguishing directions of slope. The chief advantage is that it enables minor but important details, lost on a contour map within the contour interval, to be brought out; and sometimes it can show country of striking relief in a very dramatic manner.

50c 350th Anniversary of Benguela single

Profile Relief

10p Map of Colombia single

Hachures Relief