Fig. 1. (a) A schematic representation (brick model) of the assembly of the clay and solution effective media and (b) the corresponding equivalent circuit (Bonanos et al., 1981). R_e is the electrode impedance, g_s is the conductivity of the solution element, c_s is the capacitance of the solution element, g_c is the conductivity of the moist clay element, and c_c is the capacitance of the moist clay element.