A map legend generally specifies the contour interval on the map, however occasionally simply a component of a map is available. Understanding how to compute the interval will become a precious skill.
On most of the maps, every fifth contour line, indicated as a heavier or darker line, is an index line or index contour.
What is Contour Interval?
A contour interval is a vertical distance or the distinction in the elevation between the two contour strains in a topographical map.
Generally, there are a variety of contour intervals for the more than a few maps. Taking the vicinity to be mapped, contour intervals are considered. In each map, on the right-hand backside side, the contour interval is described. The normally utilized contour interval is 20 toes for a 1:24,000 map scale. To calculate contour interval, we want to divide the distinction in elevation between the index contour strains by way of the wide variety of contour strains from one index contour line to the next. For example, if the distance 200 is divided by way of the quantity of lines, the place the wide variety of traces is 5. The contour interval is equal to 200 / 5 = 40, or 40-unit contour intervals.
Every factor on a contour line is of the genuine equal elevation. In different words, contour traces join factors of equal elevation.
By definition, contour traces separate factors of greater elevation from factors of decrease elevation. This skill it is continually feasible to outline an “uphill” route on one facet of a contour and a “downhill” route on the different side.
Contour traces in no way cross. They might also come very shut to every different (e.g. alongside a cliff), however through definition they might also by no means go every other.* This is due to the fact one area on the floor of Earth can't be at two distinct elevations!
Contour traces by no means split. Instead, contours shape closed loops. These loops comply with the form of the land, and may additionally lengthen previous the area of the map.
Closely spaced contours point out a steep slope, whereas contours that are spaced a ways aside point out a mild slope or nearly flat surface.
What are Contour Lines and Topographic Maps?
The extraordinary attribute of a topographic map is the use of elevation contour strains to exhibit the structure of the Earth's surface. Elevation contours are imaginary strains connecting factors having the equal elevation on the floor of the land above or under a reference surface, which is normally suggest sea level. Contours make it viable to exhibit the peak and structure of mountains, the depths of the ocean bottom, and the steepness of slopes.
USGS topographic maps additionally exhibit many different types of geographic elements which includes roads, railroads, rivers, streams, lakes, boundaries, vicinity or function names, mountains, and an awful lot more. Older maps (published earlier than 2006) exhibit extra points such as trails, buildings, towns, mountain elevations, and survey manage points. Those will be introduced to greater modern maps over time.
How To Read Contour Lines?
A rapid look at a topographic map will supply you a universal thinking of the landscape. Is it flat or mountainous?
If every line represents an equal factor of elevation, then any trade in elevation would lead to inconsistent line spacing, right? For example, numerous contour strains spaced shut collectively would point out steep terrain, whilst traces spaced a long way aside would point out a gentler slope.
What are the three elements that have to be regarded upon planning and designing of a contour interval to be used for a topographic map?
Scale of the map. The contour interval is stored inversely proportional to the scale of the map. …
Purpose of the map.
Nature of the ground.
Availability of time and funds.
What are the 5 Rules of contour lines? Rule 1 – each factor of a contour line has the identical elevation. Rule two – contour strains separate uphill from downhill. Rule three – contour traces do no longer contact or go every different besides at a cliff. Rule four – each and every fifth contour line is darker in color.
What are three sorts of contour lines?
There are three sorts of contour strains you’ll see on a map: intermediate, index, and supplementary.
Index traces are the thickest contour traces and are typically labeled with a range at one factor alongside the line. …
Intermediate strains are the thinner, greater common, strains between the index lines.
What are the geographical aspects shaped with the aid of contours? A single contour line joins the locations of the identical elevation. It can assist to distinguish between mountains, ridges, plateaus, valleys, hills, gullies, etc. It can additionally differentiate between a steep and mild slope of a hill or mountain.