California Code, Public Resources Code - PRC § 3904

As to any placer mining claim which has been otherwise validly located or relocated since July 20, 1935, and as to which claim the locator or relocator has not performed the work thereon required by former Sections 1426da and 1426dc of the Civil Code  1 for the reason that literal compliance therewith was not feasible, the locator or relocator may perfect his or her claim by excavating an open cut thereon and removing from the cut not less than seven cubic yards of material if the work is completed not later than December 14, 1935.