Sand beaches differ widely with respect to their firmness or hardness. On some beaches walking is tiresome and motoring impossible; while others are ideal speedways owing to the stone-like hardness of the sand. A sea beach which presents within the distance of a fraction of a mile the possible extremes of firmness and lack of firmness and various intermediate degrees of hardness is described in detail. The factors responsible for the great contrasts in sand structure represented by these differences are pointed out and demonstrated by experiments. The conclusion is reached that the close-packed and loose-packed structures responsible for firm and soft sands may under favorable conditions be perpetuated in the sandstones resulting from the eventual consolidation of beach and bar sands and have considerable economic importance.