Your answer was sink holes. people have made the same choice.

Every so often, you can read in the newspapers or see on television a where sink hole has suddenly opened up and gobbled up someone's car or house. But sink holes usually don't appear in such neat patterns nor do they like sharing space with other sink holes. Sink holes this close together would probably merge into one giant hole in the ground. Also, sink holes are almost never perfectly round, like the images in this picture.

The answer is irrigation fields. This picture is from Al Kufrah oasis in southern Libya. Libya is a country located in northern Africa. In this desert area, the only constant suppy of water comes from underground.

To make it possible to grow certain types of plants, the people who live here must irrigate the desert. They use a very long pipe with holes in it which turns around from the center of each field like the big hand of a clock. The water sprays out of the holes and brings life to desert land. Each round field in this image has a diameter of one-half mile and the entire area is about 20 miles across!

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