Geophysicist Don Johnson pushing the ground penetrating radar unit across a grid square on the Ranelius site.  The antenna (the large white box) sends out several pulses of energy into the ground with every rotation of one of the rear wheels of the cart. When the signal bounces back, the receiver collects and records the amount of time and the strength of the signal.  

Unfortunately (for a geophysical survey) trees are unavoidable on a forested site, and have to be gone around.