Electrical Resistivity, ohm-meters:Data from resistivity surveys are customarily presented and interpreted in the form of values of apparent resistivity ρa.  Apparent resistivity is defined as the resistivity of an electrically homogeneous and isotropic half-space that would yield the measured relationship between the applied current and the potential difference for a particular arrangement and spacing of electrodes.
Rate of Penetration (ROP), meters/minute:The rate at which the direct push head can break through rock beneath the surface until it reaches the final depth.