Used to indicate whether the data from the survey is the electric resistance value, the appearance of Earth. Many types of stone that stream flows through non-electric resistance value of pure substances.
Using survey data to indicate that a specific electrical resistance of the soil appear. The stream flows through several rock types. Not the actual electrical resistance of a pure substance.
Used to indicate that a specific resistance value data from the presence of soil. Many rocks stream flow. Is not the true resistivity of pure substances.