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A topographic map simply represents a 2-dimensional portion of the 3-dimensional surface of the land area. Topography, in short, shows the shape of some land, and the topographic maps refer to the land surface. These are the tools which are utilized for geologic related studies since they show the configuration of the surface of the earth.
The next question which comes to your mind will be what does contour mean and how does it aid a hiker in his or her journey? The answer is simple, and we can say that it is just like an outline which indicates the shape or the form of a land surface.
What Are Contour Lines?
Before getting into the details, let us understand or define a contour line! The contour lines on a map help in deciding the elevations and these lines are developed by connecting those points which are having equal elevation – the elevation points to the height of contour in meters, feet which is above the sea level.
In the majority of the topographic maps, the index contour lines will be marked darker and will be projected with their elevations too. The lighter lines will not be showing any elevations.
However lighter contour can be well spotted by carefully counting the downs and ups, starting from the nearest index contour line. This should then be multiplied by the obtained contour interval. The answer will give you details on what is a contour interval. This interval which is seen below the scale will be mentioned clearly on each topographic map.
What Is the Purpose of Contour Lines on A Map?
A contour line will connect points which are having equal elevation. If you are trekking along a contour line, then you will not be moving downhill or uphill. This is the reason why might hikers find topographical maps useful.
What Do Topographic Maps Tell Us?
You won’t be going uphill or downhill while hiking along a contour line. This is the purpose of a topographic map as they will let you get the shape of a three-dimensional mountain on a two-dimensional map.
The steep of the slope increase depending on how close the contours are and the fall line (pointing the direction the water is running) will be at right angles to those contours. There won’t be any topographical map without stating the relief.
Contour is considered as the best and the basic technique of projecting relief on the two-dimensional plane maps. As mentioned above, the contour lines represent points which are of the same elevations. It is one among the signs which is seen on the maps, however, cannot be ever witnessed on the ground the way rivers or the trees are.
What Does A Contour Line Show?
Imagine that you are out for hiking along with your family members or with a group of friends. You will be certainly taking the map out of your backpack and check for the two trekking trails. The first path might be having contour lines which are closely spaced.
On the other hand, the second route is different and has contour lines which are widely spaced. Which one would you prefer to choose?
Well, if you are slow and steady hikers, then you will be preferably picking up the second route which is widely spaced since the contour lines show a gradual slope.
However, if you are picking the second route, then you might be a free climber who can just scale any mountain with a pickaxe. This is because contour lines are close together and project the fact that it has got a steeper slope.
In short, we can say that a contour line will connect points which are having constant as well as identical values. For instance, contours one an elevation will be having constant heights, and this will be the same on every line.
If you have a very close contour line, then there will be a depression or hill or mountain on your way. You won’t be able to spot it out unless and until there is a label on the contour line which states it well.
On the other hand, there are certain maps in which the cartographers will be using hachures or teeth marks for the depressions at volcanoes or the craters since it points to the elevation which goes either up or down.
Uses of Contour Lines
The contours lines are usually used for representing constant elevation and help in projecting the topography of a particular landscape.
However, in the isogon (magnetism), isopleths (meteorology) as well as in the isochrones (drive time), these different contour lines serve different purposes. The closeness of these lines always points to the slope. Irregular contour lines project terrains which are rugged.
While reading contour lines, remember that it is exceptional in nature for these lines to cross, but chances are there in case of cliffs and overhangs.
The Importance of Contour Lines
The uses of contour lines are mentioned above. Now coming to its relevance part, they can be considered as the most important method in projecting the fall as well as the rise of land on a map.
They represent regions which are of the same height and above the sea level. In addition to this, they also help in providing information to the hiker regarding the slope of the land. The steeper slopes will be marked with closed lines.
What Are Contour Lines Used For?
On a topographic map, contour lines are what that connects the points which are having same elevations that are above the sea level. These maps are simply an illustration with the contour lines.
For instance, in the topographic map, everything including the hills, valleys, gentles and the steepness of the slopes are clearly stated in a manner which could be read by the hikers.
What Color Are Contour Lines On A Topographic Map?
These are the lines which equate areas which are of the same height. They will usually be marked brown or orange. Some of these lines are having an elevation below or above the sea level, and this will be mentioned on them.
The blue triangle shows the triangulation pillar.
How Is Distance Measured On A Contour Map?
The distance is measured in the same way which we use on the standard maps. If you are searching for an image of a specific area which is scaled down, then the only difference which you might observe is that you will be provided with some information regarding the altitude. However, these factors won’t be affecting the calculation of distance.
Another thing is that the distance between contour lines can also be easily noted. Those lines which are very closely spaced will be indicating steep slope since the elevation changes rapidly within a small area itself.
On the contrary, those lines which are widely spaced will be showing a shallow slope. Above all, those contour lines which touch each other will point to vertical or else steep rise, same as that with the canyon wall or the cliff.
Different Types of Contour Lines
Majority of the times, the contour lines will be forming concentric shapes just about each other. Often contour lines will form concentric shapes around each other.
Now let us define what are the three types of contour lines and there features in detail. The three types of contour lines are an index, intermediate and supplementary.
These are contour lines which are projected with a heavier mark, and due to the same, they will be the first thing which catches your eyes while you take a walk through the topographical map.
Just like any other contour lines, they will be forming shapes or some kind of concentric circles and every index lines will be equally spaced from one line to the subsequent one. Normal intervals between the lines will be 100 or 200 feet even though lesser or greater numbers are doable.
In between every pair of the contour lines, there will be a set of intermediate lines. They typically come in sets, and each of them will be representing an equal amount of changes of elevations among each line.
The contour line example for this type would be like, you will be having the index lines placed around 100 feet apart. The possible setting will be like; there would be four intermediate lines which are placed in between every pair of these index lines.
These kinds of contour lines are showed on the map with dashed lines. They are drawn at all one elevation.
On the other hand, they represent it on the map in a very different way from the previous two types of contour lines in their spacing or elevation changes. They will be projecting half the changes in the elevation which is seen in between the index and the intermediate contour lines.
Rules of Contour Lines
Rule 1: In a contour line, each point will have the same elevation.
Rule 2: The lines help in the separation of the uphill from the downhill.
Rule 3: Except in the case of a cliff, the contour lines won’t ever touch or cross each other.
Rule 4: There will be a darker color on each fifth contour line which is in turn called the index contour line.
Rule 5: The lines will be closer for steep areas and in case of flat terrain, it would be farther apart.
Rule 6: - The contour lines that form a circle indicate the top portion of a hill.
Rule 7: Hachure marks will be provided for every closed depression, and this will be mostly on the downhill portion of the contour line.
Rule 8: If the map crosses a valley, then the lines will be forming a V pattern to indicate the same. This is the same in case of indicating drainage. The top or the tip portion of the V pattern will be pointing uphill.
Rule 9: V or U patterns will be formed with the contour lines while crossing a ridge. The top or the blunt end of the pattern will point downhill.
Rule 10: The lines which are there on the opposite sides of any ridges or the valleys will be seen in pairs.
What Do Contour Lines on a Map Show?
In the case of cartography, the contour lines will be joining points which will indicate equal elevation which is above the sea level (say mean sea level). These kinds of maps perfectly describe contour lines, for instance in a topographic map it explains the hills as well as the valleys and the gentleness and the steepness of the slopes.
What is a Topographic Map?
Now lets us take a short walk and understand thoroughly about what's a topographic map. It is simply a map which details the two-dimensional illustration of the human-made as well as natural characteristics on the Earth's surface.
The Topographic Maps and Contour Lines!
The topographic maps are used for several applications including fishing, hunting, hiking, resource management and many more. Among these, the unique feature of the topographic line map is that it helps in projecting the three-dimensional shape of Earth's surface, which in turn is shown using the contour lines.
Now you will know what contour lines are and how do they work. Well, just like stated above they are the imaginary lines which help in connecting the locations that have the same heights or altitude. They help in indicating the height as well as the steepness of the mountains and the slopes in a two-dimensional map surface.
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What Are The Lines On A Topographic Map Called?
According to the topographic map rules, these maps will be showing the topography or the land contours using contour lines. They are just curves which join those points of the same height or altitude. In other words, we can say that each point of the map which is having 100 meters elevation will be 100 meters above the sea level.
Elevation Lines on a Topographic Map
The contour lines represent shape or the elevation of any terrain. They are found to be really useful since it helps in illustrating the shape of the land which you are hiking on the map. Here is one of the best ways to summarize the contour lines.
Just take an object like a ball or something and then shine some red laser pointer on the side of the object. The line which you will be a witness now will be similar to the topographic contour lines.
For keeping theories simple, a topographic contour map will point outlines for some particular elevations alone, and these contour lines would be evenly spaced. These evenly spaced ones will give you the answer for what is a contour interval.
To decide the elevation contour lines, you need to check with space which is there in between the lines. If they are really close to each other, then it would be a steep slope, and if they are widely spaced, the terrain will be flat.