the pipes 16 if desired pumps may be positioned inside the pipes 16 rather than in sumps 20 so that they can be operated during the rf heating periods referring now to fig5 there is shown an alternate embodiment of the invention oil shale body 10 contains electrodes 70 spaced apart therein electrodes 70 having apertures 72 adjacent the lower ends thereof through which products derived from kerogen in the oil shale may pass at the rf frequency electrodes 70 which may be for example six inches in diameter are preferably one quarter wavelength long in the oil shale and spaced apart by distances on the order of one half their length or one eighth wavelength or less in the oil shale as shown in fig5 the horizontal scale is accentuated to illustrate details of the electrode and feed structure for example electrodes 70 at a frequency of one megahertz may be spaced apart by a distance of about forty to fifty feet and the length of electrodes 70 is for example about eighty to one hundred feet electrodes 70 are positioned wholly within the shale body 10 and are supported at the ends of producing tubings 76 which extend to the surface of the formation and may be for example two inch steel pipes pipes 76 act as the central conductors of coaxial cables in which the outer conductors are casings 78 which may be for example eight inch inside diameter steel piped coated inside for example with copper conductors 76 are insulated from outer conductors 78 by insulating spacings 80 which are attached to pipes 76 and loosely fit in casings 78 the lower ends of casings 78 have rf choke.