Fog that forms when the ground cools.

It rises less than about 200 feet (61 meters).

Another tool used by archaeologists to search for archaeological features beneath the topsoil.

Ground penetrating radar or GPR works by sending high-frequency radar pulses from an antenna into the ground.

Buried materials or sediments and changes in the subsoil reflect the radar pulses back up to the antenna, and by measuring the time that has passed between when the pulses were sent and when they were received; an understanding of the changes in soils, sediments, and features can be determined.