This
survey was not successful at locating underground tree trunks and stumps. A major part of the difficulty was that
other soil materials had a larger contrast than that of the trees. For example, it appears that changes in the
depth and thickness of an organic (i.e. forest litter) layer may have been the
source of some geophysical anomalies; it is also possible that discontinuities
in an iron-bearing strata may also have caused anomalies. While some buried trees may be detectable at
this site, their detection is rare relative to other unwanted finds.
Two different geophysical instruments were applied to the search. A ground-penetrating radar furnished approximate soil profiles to a maximum depth of 1.5 m. Radar antennas with two different frequencies were found to allow profiles for only a short span of depths. A medium resolution antenna was best for profiling within a depth span of 1.0 - 1.5 m, while a high resolution antenna could detect features within the range of about 0.5 - 1.0 m. Neither antenna was found to be very suitable for trying to locate trees that were shallower than 0.5 m; unfortunately, it is this shallow zone that is unfrozen and therefore easier to excavate.
The second instrument of this survey was a conductivity meter that measured the surface-weighted average electrical conductivity of the soil to a depth of about 1.5 m. This instrument measured large changes in conductivity at the coal layer. However, the contrast in conductivity between the trees and the surrounding soils was uncertain. While the conductivity meter mapped distinct geophysical anomalies, none of these had the linear pattern that may be expected for a buried tree trunk.