I am crowd sourcing this technical question: i am going to put a flexible rod down into a twisting convoluted animal burrow, with temperature loggers along the rod's length, and leave it in the burrow to record temperatures at different depths over a winter. It could go as much as 7 meters deep at the bottom. How do I accurately measure depth (=vertical distance to the soil surface) at each of these points? An altimeter or GPS is not accurate enough. And i can't dig up the burrow. Is there a device that does this?
RB
