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A specific physical interpretation of the effect of relative permittivities εr and conductivities σ upon the amplitude and phase of propagating electromagnetic surface waves is given, where ϵr and σ characterize the layered material regions of a planetary lithosphere. The interpretation is made possible by the availability of simple formulas for the fields of vertical and horizontal unit electric dipoles near interfaces between regions of matter; the earth's lithosphere at its interface with salt water is used as an example. The ranges of εr, σ, frequency ƒ, and radial distance ρ over which the formulas apply are shown to be quite broad. The E component (the radial electric field in region 1, characterized by complex wave number K1 and adjoined at a planar interface to region 2, characterized by k2, where |k1|2 » |k1|2) is discussed in detail. The attenuation of 20 log10 |E| as a function of ρ and ρ/δ2, Where δ is the skin depth, is illustrated for conductivity ratios σ21 = 10−1 to 10−3, over a range of ƒ from 1 Hz to 105 Hz. |E| is shown to be significant for determining permittivities ε2 at the higher frequencies in this range. The use of |E| to infer conductivities σ2 at lower frequencies in shallow sounding of the earth's sea floor is discussed in terms of specific lithological and sediment-related parameters. The technology required to transmit and receive 20 log10 |E| at freshwater and saltwater interfaces with the earth's crust is addressed. A specific experiment is proposed for testing a specialized insulated antenna for seafloor use in shallow coastal waters at 1 kHz.