Go to Step 1  

Now that you know the nearest index contour and the direction of slope, recheck the contour interval. Now you will count up or down, by the amount of the contour interval, until you reach the contour that is nearest your point. There are two questions on each map. First answer the contour interval question, then check the answer. Next, answer the elevation question; write down the value and then check your work by clicking on the question.

Guess what? You are almost finished!

Practice what you just learned. Count intermediate contours!

   
Go to Step 2    
Go to Step 3    
Go to Step 4
         
               
                         
             
                         
     
                         
                       
                         
       
ANSWER: The contour interval is 40 feet.
How do I know? There are 200 feet between index contours, if you subtract 8,200 from 8,400. Then you divide 200 by 5, you get 40 feet. Why 5? Because you must add one index contour in your counting for a total of five contour lines.
           
                         
                       
                         
       

ANSWER: 8,320 feet.

WHY? Because the Red X is on the third contour between 8,200 and 8,400, if I begin counting at the 8,200. If the contour interval is 40 feet, then I count up by 40 for each contour (8240, 8280, 8320).

I can also count backwards from 8,400. The Red X is on the second contour, if I am counting form the 8,400 line; 8400, 8360, 8320.

Also note that there are several "spot elevations" on this map.

            
                         
                       
                         
     
ANSWER: The contour interval is 10 feet.
How do I know? There are 100 feet between index contours, 650 amd 550. If you subtract 650 from 550, you get 100. Then you divide 100 by 2, you get 50 feet. Add that value to 550 and you get 600 which is the value of the index contour without a noted value. Next divide 50 by 5 and you get a contour interval of 10 feet. Why 5? Because you must add one index contour in your counting for a total of five contour lines.
         
                         
                       
                         
     

ANSWER: 580 feet.

WHY? Because the Red X is on the third contour between 550 and 600. If I begin counting at the 550 and know the contour interval is 10 feet, then I count up by 10 for each contour (550, 560, 570, 580).

I can also count backwards from 600. The Red X is on the second contour, if I am counting form the 600 line; 600, 590, 580.

          
                         
                       
                         
       
ANSWER: The contour interval is again 40 feet.
How do I know? Notice on the left side of the map you see index contours 8,200 from 7,800; you also see 8,200 and 8,000. There are 200 feet between index contours, if you subtract 8,000 from 8,200. Then you divide 200 by 5, you get 40 feet. Why 5? Because you must add one index contour in your counting for a total of five contour lines.
         
                         
                       
                         
       
ANSWER: 8,320. This is an interesting contour. Notice that as you move from 8,200 to the Red X, you see the contours start to "close". This means that you are going uphill to the eventual peak of the hill or mountain. In this case, the Red X is on a near circular contour. It is the third contour from 8,200 on both sides; it is surrounded by one index contour, the 8,200. Therefore, counting by forty, the elevation of the Red X is 8,320.
          
                         
       
NOW YOU ARE READY TO GO ON TO STEP 4. IF YOU FEEL LIKE YOU NEED A LITTLE MORE PRACTICE, SO BACK TO STEP 1, STEP 2 AND/OR STEP 3 AND PRACTICE A LITTLE MORE.
         
                         
       
Go to Step 1Go to Step 2Go to Step 4
          
                         
Web Site designed and maintained by Lisa Keys-Mathews.
Last update: 10/30/03