One of the richest sources of clues to the prehistoric way of life is an archeological "dig", a site where ancient objects are deeply buried. Archeologists base their choice of the site for a dig on clues such as the shape of the ground surface and stories or traditions that indicate people once occupied the site. Sometimes a dig is made where artifacts have been found by accident. A farmer plowing a field may turn up stone arrowheads, or a bulldozer operator may uncover the foundations of an accident building.
Even before starting to dig, or excavate, archeologists make a map of the site. The map is blocked off in numbered squares so that workers can later identify exactly where an artifact was found. Next, the soil is carefully removed layer by layer. If a worker comes upon an artifact - perhaps a piece of pottery - he or she uses a small, soft brush to remove the soil without damaging an object. The loosened soil may be sifted through a fine screen so that even tiny objects are not lost.
The artifacts are photographed, labeled, cleaned, and then studies carefully to classify and identify them. Experts spend hours putting together fragments of bone, pottery, or other artifacts. They make drawings to show what an object may have looked like unbroken. Samples of soil, clay, paint, and the like may be sent to chemical laboratories to be analyzed.
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