**11. Very low frequency electromagnetic method**

Very Low Frequency (VLF-EM) is an effective reconnaissance geophysical tool for mapping geologic features. It may be used wherever an electrical conductivity contrast exists between geological units, this includes Fault mapping, Groundwater investigation, Overburden (summation of all the materials on the bedrock) mapping, contaminant mapping. Electrical conductive features include fault zones which tend to be more conductive than the surrounding bedrock or host rock. Other conductive geologic units include moist, clayey or fine grained soils which tends to be more conductive than dry, sandy or coarse grained soils. Hence, these geologic objectives are reasonable "targets" and can be mapped using electromagnetic methods. In reconnaissance mode, VLF profiles can be run quickly and inexpensively to determine anomalous areas which requires further investigation.
