RIB VAULT

A 'rib vault' or 'ribbed vault' is any vault reinforced by masonry ribs. A rib vault may be a quadripartite rib vault (which is divided into four sections by two diagonal ribs) and a sexpartite rib vault (a rib vault whose surface is divided into six sections by three ribs).
Most ribbed vaults are quite common in early gothic buildings, ribbed vaulting is commonly made out of stone to hold the weight of wooden ceilings, ones made out of stone wouldn't be as durable, for example, the chapter house in Southwell Minster's vaulting is made of solid stone and has no central pillar, so the chances are it will collapse very soon if action doesn't take place.
Ribbed vaulting can be common in Salisbury, Lincoln, Southwell, Wells, Bristol, Norwich and Worcester Cathedral.
There is more information on the rib vault at the main article for vaulting.