8. Arenaceous Strata unconformable on an Oil-generating Formation.—Occasionally a formation, though a parent source of petroleum, does not contain porous rocks suitable for oil accumulation. But a second formation resting unconformably upon the first may be admirably situated for receiving and storing the oil, for this second formation probably contains the necessary sandstones, and also all the unconformable strata are likely to be more or less arpaeeous where they abut against the plane of unconformity, thus facilitating the transfer of the oil from the rocks below (Fig. 9). Cases of this kind occur in California in the Coalinga Oilfield, where oil is obtained from sandstones in the Miocene which lies unconformably over the Eocene; also in Roumania, where the Meotic formation transgresses over the Saliferous.