29 SUNDIAL. A stone sundial is in this small clearing. Anyone approaching to within thirty feet of it will feel a momentary resistance to forward progress as they breach an invisible dome-shaped membrane-like barrier surrounding the sundial.
The shadow-caster (gnomon) of the sundial can be adjusted. Moving it all the way to the right changes the local time (within the dome) to double speed. Moving it to the left does the same to lower the speed of time to one half relative to the outside world.
Clues will be readily apparent, as the movements of birds, clouds, etc. will change based on the sundial's setting.