2. A sand bank in the sea, or a rock, or ledge of rocks,
rendering the water shallow, and dangerous to ships.
On the tawny sands and shelves. --Milton.
On the secret shelves with fury cast. --Dryden.
3. (Mining) A stratum lying in a very even manner; a flat,
projecting layer of rock.
4. (Naut.) A piece of timber running the whole length of a
vessel inside the timberheads. --D. Kemp.
{To lay on the shelf}, to lay aside as unnecessary or
useless; to dismiss; to discard.