Is it a Hill or is it a Hole?

Look at the figure to the right. You should be able to recognize that you are looking at two hills... OR are you?  Let's assume the contour on the lower left is sea level.  Can you figure out the rest of the contour labels with a contour interval of 10'?...

Now lets consider another possibility.  What if the closed contours on the right were not representing a hill but rather a HOLE. Can you see that the contour shape would be the same, but the labels would be different?  It turns out that there is a way to determine whether closed contours (ones that make a complete circle) are a hill or a hole.  If they represent a hole, little lines (called hachures) are added which point towards the bottom of the hole.  Now can you predict what the contour labels will be for the two circles on the right? 

CAUTION: keep in mind that if you climb up a hill and cross through an elevation, when you crest the hill and go back down you must go back down through the same elevations (contours) as you went through on the way up.  Study the figure to the right and pay close attention to the 300 contour interval.

So the map on the right shows what a hole would look like.  Notice how the 30 foot contour lines must be repeated.

Now let's practice what you have learned. Use the map below to answer the questions on your handout. HINT: The elevation of the coastline (at "A") is sea level.

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