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How to Find Contour Interval on a Topographic Map

A topographic map, sincerely put, is a two-dimensional illustration of a element of the three-d floor of the earth. Topography is the structure of the land surface, and topographic maps exist to signify the land surface. Topographic maps are equipment used in geologic research due to the fact they exhibit the configuration of the earth’s surface. Cartographers resolve the hassle of representing the 3-dimensional land floor on a flat piece of paper through the use of contour lines, therefore horizontal distances and vertical elevations can each be measured from a topographic map.

How Do You Figure Out the Contour Interval on a Topographic Map?
  • Find their difference/subtract (800’-700’ = 100’)
  • Count the # of traces from one index contour to the subsequent (On this map: there are 5 contour traces from 700’ to 800’ (4 in between them and the remaining line of 700; 4+1= 5 lines)
  • Divide the distinction in elevation by means of the # of lines! (100’ divided by way of 5 traces = 20’)
  • Contour traces are a kind of isoline: (“iso-“ capability equal): all locations alongside the identical contour line have the equal elevation! No be counted the place you stand on the 100’ contour line, the elevation will usually be 100’, whether or not you’re on the N, S, E, or W aspect of the mountain. You can inform how steep the mountain is by way of how shut collectively the contour traces are to one another! The nearer the strains = the steeper A neighborhood melancholy (like a the mtn.!volcanic crater or a dried-up lake bed) can be proven on a topographic map by means of drawing hachures: brief strains that factor from a contour line towards decrease elevations.

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Identifying Features with Contour Lines

Contour strains exhibit greater than simply the steepness of a slope or the elevation of a peak. You can choose out most important land aspects on the map by means of the way the contour strains are shaped.

  • Peak: A mountain or hill that is marked by using concentric contour lines. The summit may also be marked with a name, an “X”, or an elevation.
  • Valley: A landform with a melancholy in which water, if present, would float down. Also comprehend as gullies, drainages, ravines, and couloirs, valleys are indicated through “V“or ”U“ fashioned contour strains that “point” uphill, towards greater elevation.
  • Ridge: A landform with an extended crest that slopes down on the sides. Ridges are additionally proven via “V“ or ”U“ formed contours, however these “point” downhill, towards decrease elevations. Remember, water by no means runs alongside ridge tops.
  • Saddle: A low spot between two peaks marked by means of hourglass-shaped contour lines.
Characteristics of Topographic Maps Include
  • they exhibit elevation the use of contour lines. Put simply, a contour line is a line which joins factors of equal elevation above sea level
  • they have an emphasis on displaying human contract (roads, cities, constructions etc), however may also encompass some thematic facts such as vegetation or the boundaries of country wide parks
  • they are commonly produced by means of authorities businesses – these are regularly professional mapping corporations and may additionally have both a civilian or defence purpose
  • they have nicely described requirements (called Specifications) which are strictly adhered to – these fluctuate between mapping corporations and the scale of the map
  • they have very excellent place reference structures – such as latitude and longitude, however may additionally additionally have grid lines often have extra records such as an arrow pointing to Magnetic North as nicely as True North.

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8 Things to Remember About Contour Lines
  1. Contour traces join factors with equal elevation
  2. Contour traces by no means intersect
  3. Contour strains are shut collectively in steep terrain and in addition aside in flat areas
  4. A hill or mountain is represented through round contours
  5. A contour that closes with hachures is a depression—with the hachures pointing inward
  6. Contour strains create ‘V’ or ‘U’ patterns when they go a valley or river. The tip of the ‘V’ or ‘U’ constantly factors uphill
  7. Contour traces are drawn on the naked Earth
  8. Contour numbering reads uphill, i.e., the pinnacle of the variety is uphill and the backside is downhill
Types of Contour Lines

The sorts of contour strains are Index lines, Intermediate traces and Supplementary lines.

Index strains are the thickest contour traces and are typically labelled with numbered. They exhibit elevation above sea level.
Intermediate strains are thinner traces between Index Lines.
Supplementary strains are the dotted traces and they are used to exhibit flatter surfaces.

How To Read A Contour Map?

First, it is necessary to comprehend that contour maps are a famous way to characterize the three-d terrain of an area. Contour strains are used on maps to illustrate variants in elevation. By lining up contour strains on a map, you can see how the elevation modifications throughout the area and are in a position to discover landmarks.

The nearer that these strains are to every other, the steeper or sharper the slope of this characteristic will be. This facts can be useful when making an attempt to become aware of facets in a map due to the fact understanding their slope can provide you clues as to what kind of function they may be.

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