First, although the professional archaeologists are often observing rather than digging, this is some of what they are supposed to do:
- ensure that we are working safely, not stabbing each other with trowels, falling into trenches full of water or puncturing gas mains
- keeping the work scientifically accurate, for instance making sure earth, and therefore finds are not falling from modern layers to mediaeval layers, thereby losing the proof that it is a mediaeval layer.
- working out what to do next based on what the features might represent, and what we might find by digging out another layer in this particular corner.
- they are learning how to do something
- they are listening to the archaeologists debating a hot concern about dating or identifying gatehouses from cesspits
- they are tired from this unfamiliar manual work
- no one is paying us, we'll stop when we damn well like!
This particular group were watching one volunteer work because they were posing for a photograph, which is another frequent occurrence.