What I would expect to be on topic, all the time or almost all the time:
- archaeological geophysics
- stratigraphy (including archaeological approach, with Harris Matrix and like?)
Where I am not sure, and I would expect at least some (but not all) questions to be on topic:
- interactions between earth (including climate) and ancient people
- archaeological dating of various events studied by paleo-(insert earth science here)
- how climate changes influenced ancient people (and if and how ancient people influenced climate)
- how did mining, agriculture and other past human activities influenced earth etc.
- ancient mining once again
- what materials could people reach in certain time and space
- their mining techniques
- flint knapping - techniques, how good are various rocks for knapping etc.
What I don't expect to be on-topic at all:
- any social and/or relegious aspects of archaeology (perhaps with exceptions of ways how people perceived and reflected earth and specific landmarks, i.e. cult of mountains in some cultures?)
- production of artifacts that is not directly tied to earth, geology, pedology etc.
- almost anything else