Archaeologists also find larger features, such as the ones visible in this photograph. These are called pits, because they indicate areas where, in ancient times, a hole was dug and then refilled. The ancient Indians used such pits for storage and cooking. When they fell out of use, they were refilled with dark topsoil that was full of village refuse. (That's why nowadays they appear darker than the surrounding subsoil.) Occasionally, pits were also used as graves; such features are called burials.
Click here to see a video of archaeologist Trawick Ward explaining why ancient pits were dug and refilled. (If the video fails to play, try these alternative formats: Quicktime, MPEG-1, MPEG-4, RealPlayer.)