Archaeological survey means looking for clues about people from the past, looking for archaeological sites (any place where there are clues).
Digging holes in the ground (excavation) is only one of the methods of archaeological survey. Archaeologists use many different ways to find archaeological sites and to work out what might be there without excavation. Often they use lots of these ways together.
Here are some of the more common ways of finding out what might remain from earlier times: