why dose it take archaeologist many years to excavate a site?
Basically they have to work by hand. Going into a site, they do not know exactly where the artifacts will be...how deep, how close together etc. Also, the objects they seek can be very small. Using mechanical tools (excavators for example) can damage or destroy artifacts. They also want to map the locations of things they find, to see if there is a pattern...for example, finding a fire remnant and bones that show charring might indicate a kitchen given one pattern, or a massacre site given another. The closer they get to an object, the smaller the brush and the more delicate the handwork. There are other issues...the deeper one digs, the more you have to shore up the sides or widen them to avoid cave-ins...there are safety concerns. Also, most sites are not wasteland and they are tying them up from other uses, so permissions and agreements have to be obtained and kept. Many interesting sites have people living over them at the surface who would not appreciate having their house or business collapse because of an overzealous dig.
