Understanding Contour Lines

the lab is gone and there's no one here to help you now hi I'm John McCain from survival resources I wanted to do a short video today it's not going to be real long and what it's going to be is understanding contour lines outside of magnetic declination I find that many times the students has a hard time comprehending or actually visualizing contour lines so I wanted to do a real quick video and I hope this helps those who don't understand them to better understand them those of you guys out there that already know all this stuff then it's probably not going to be a lot of help to you but there should be a lot of help to those people who sometimes just don't quite understand them and I want them to be able to visualize the topography so let's get started on this video okay I'm going to use a USG map here to help explain some of the stuff about contour lines for you which have to understand is there seven colors used on a map that's at seven one of those is brown and the brown is always used as contour lines and you will see that all of these little squiggly lines here these are all contour lines and this is what allows you to actually see and perceive the topography what the land looks like once you understand them okay each one of these little squiggly lines represents the elevation above sea level the difference in elevation between each one of these lines remain the same on any specific map now this actually allows you to see this land in three dimension okay but there's certain rules that pertain and understanding these rules are going to allow us to better understand these contour lines first the height and the distance between these lines is what we call the contour interval okay these this contour interval is indicated always at the bottom Center the map right below the scale if you look down here you're going to see the contour interval is 20 feet that means if 20 feet distance between each line increases or D raises it does so by this 20 feet okay you'll see I've moved the camera to another section of the map here in order to further discuss contour lines okay you will notice that each fifth line is thicker okay this is particularly notable right here and right here every fifth line you will also know that every thick line has the actual number written on it which is the elevation above sea level if these numbers go up in number then you're going uphill if these numbers go down then you're going downhill very simple to remember numbers going up you're going up numbers coming down you're going down okay all of these contour lines you will knows have no beginning and they have no end they're all a continuous loop and if you walked around this entire loop here you would never go up and you would never go down you would remain on the same elevation all around every one of these lines you also note that the closer these lines get together particularly over here that this is steeper topography if these lines were real close together almost right on top of each other you would actually be on a cliff that would show that it would be straight up and down now when lines are further apart like here this is less of a steep grade it's a very it would be much easier to walk up here than it would be to walk up here because this is less steep okay you also know there's these shapes here dr u shapes and these VRU shapes they point always uphill increased elevation they would represent a valley a ravine or something like that if they were pointing down then they would indicate a ridge or a spur you can see over here that there's some going this way that shows you that this is a ridge and these would be going in this direction and you would see that right here it less steep and over here much less steep than it would be if you tried to come up this side here an hourglass type of shape and you will see here and here this would show you that there's some type of a pass going through here okay a lot of times the peak of a mountain or a peak of something would be marked with an axe or actually show you the elevation you can see right over here there's an X and it says two one six three you will notice it's not an even number like the others because this is the actual elevation of the top of that then we'll go back to this hourglass shape or this peak you notice that you had a pass through this topography here that it would be much easier to go through here than it would be to go through here okay one of the things I want to warn you about in regard to topographical maps and contour lines is that contour lines do not show everything they can't show everything because every contour line is a distance and height or going down from one line to the other therefore anything that is less than the contour interval you won't see and I want to explain this because sometimes I'll have a student be walking along and they'll they'll come to this cliff and they look at their map and they don't see the cliff and it's going down and they say I must be in the wrong place there's no cliff indicated on my map here but what this means is if you'll see here here is your topography here is your contour lines this is what it looks like from the side if you come up right here you will notice there's a dip here okay this dip as you're walking along here is a cliff but the reason why it doesn't show is because it's less than the contour interval which means that these contour lines were 20 feet high from each other going up and you hit this cliff this cliff is less than 20 feet it could be 18 19 12 whatever but if it's less than the contour interval less than the 20 feet then it won't show up anywhere on the map if this was exactly 20 feet then there would be another contour line right there to indicate that but there isn't so be careful when you're walking along out in the woods or wherever you are and you come to something that's not shown on the map as a contour interval it could mean it's less than the contour interval in other words a cliff could be 18 19 feet deep but it's not going to show because unless it's 20 feet deep it won't become another contour line I hope that helps explain one little warning here that I always like to give out the students okay we really have the basics of contour lines out of the way what I've explained so far really should give you an understanding of what they are how they work and how you can visualize the typography my problem is a lot of times my students still couldn't really visualize how when you went up in contour interval or down it would actually show the shape of the land and that's what I really like to do is have a student understand I want a little light to go off and have them go now I get it so I thought about this a long time and I said you know if I could build an actual mountain and cut it all up into pieces you know slice it off like you would a ham with a slicer then maybe if we built this in front of them then they could actually understand how the contour lines showed or represented to topography so I got my self into the woodshop and I actually made a mountain and then me and my wife sat there and we carved between each contour line in order to give the shape of it and then we painted it green so it would look like a mountain so what I'm going to do now is I'm going to show you this little training aid that we put together and hopefully this will help those who are still a little confused that when they're done they'll say now I get it and that's all I'm hoping for with this video okay as you can see what I've done is I've drawn a portion of a map onto a large piece of cardboard and what I've done is I've done the contour lines and I'm showing more or less of shadow as you can see the numbers go from 3,000 3,500 3,500 over here and then it goes up a little further this shows an actual saddle in a mountain now when someone looks at a topographical map and they see these lines they should immediately be able to envision in their mind what this looks like as a mountain unfortunately a lot of times they don't so building the mountain what we did is we made it so it would fit exactly onto these contour lines so let's go with the first layer here's the first layer and as you can see the remaining contour lines here is painted onto each of the other pieces so that that's your first thing now as you can see everything is going up the second piece again with the remaining contour lines is added and now we can start to see the shape that there's a lot less steepness coming up this way than there would be if you are coming over here then we add the next piece and what we just keep doing is adding these what you see on the top of these one is what's left underneath on the map each one of these as you can see is the same height all the way around so that shows you that for each contour interval if you will walk around this line you would never go up you would never go down but as you increase the different contour pieces you'll see that it starts to take shape here's another piece there's another piece there's a piece that tops off this this continues on this one over here this continues even further and then this tops it off now as you can see this actually shows you to typography of what this represents if you were just looking at this this is what you should see in your mind you would see what the ground looks like and a lot of times when we've utilized this after our class students ago now I get it now I can actually visualize the typography they can see that if you are hiking it would be easier to come up here than it would be to come up here they can also see there's a saddle here if they were going to go through here then you would come up through here and go over and go down so hopefully this little training aid will help those that were still a little confused and we hope that people will now understand that contour lines aren't real difficult they're actually very helpful in helping you understand what the topography looks like and that you should be able to envision that in your mind where there you have it understanding contour lines I hope this video has really helped those people who are having problems understanding or comprehending what they were and what they really showed anyway as always I thank you for joining us please be sure to check out our products and our articles at survival resources com again we thank you for your support and we'll see you next time around

Channel: survivalresources

Views: 177,050

Rating: 4.888103 out of 5

Keywords: Map and Compass, Navigation, Contour Lines, Understanding Contour Lines, Reading Maps, Maps, Survival Resources, Survivalresources.com, John D. McCann

Id: SP8XG-xQ2zg

Length: 12min 46sec (766 seconds)

Published: Sat Sep 12 2015