Cal. Pub. Res. Code § 2761
(a) On or before January 1, 1977, and, at a minimum, after the completion of each decennial census, the Office of Planning and Research shall identify portions of the following areas within the state that are urbanized or are subject to urban expansion or other irreversible land uses that would preclude mineral extraction:
(b) In accordance with a time schedule, and based upon guidelines adopted by the board, the State Geologist shall classify, on the basis solely of geologic factors, and without regard to existing land use and land ownership, the areas identified by the Office of Planning and Research, any area for which classification has been requested by a petition that has been accepted by the board, or any other areas as may be specified by the board, as one of the following: