A corn crib is a storage facility for holding and drying field corn in the ear, which is then used for animal feed. Its features would include slats (usually horizontal wooden ones) and/or wire netting for ventilation; doors in the ends for accessibility; and anti-rodent provisions (elevating it off ground level, tight flooring). Corn cribs can have gabled or shed roofs, but shed roofs are by far the more common type. The earliest corn cribs were made of log, but few of these survive. Most extant cribs are constructed of frame. "Keystone" shaped cribs, flaring from bottom to top, were designed to prevent settling and to shed water. These types were common in the nineteenth century.