Abstract: A sorting apparatus includes a first grating of spaced parallel bars and a second grating of spaced parallel bars positioned parallel to the first grating. Relative lateral movement of the first grating and the second grating alters the lateral spacing between the parallel bars of the first grating in relation to the parallel bars of the second grating. This enables rocks to be sorted into three piles; a first pile of rocks that will pass through when openings in the first grating and second grating are out of register, a second pile of rocks that will pass through only when openings in the first grating and second grating are in register, and a third pile of rocks that will not pass through.