Why would an archaeologist need to be careful when completing an excavation?

Archaeologists work slowly and carefully in order to recover as much information about an archaeological site as possible, which can then be used to interpret it. More specifically:

* In order to avoid damaging the artifacts they hope to recover. * To make sure as many artifacts as possible are recovered.

* In order to avoid missing changes in soil texture and colour that may indicate different layers of construction or abandonment of a site. * In order not make mistakes and to be exact in what they're working on.