Graphs like this are common in archaeology. This shows the seriation of 15 archaeological sites,. The percentage of types of pottery found at each site is shown by the size of each bar. Collared and High Collared sherds are most common at the Rife and Van Eden sites, while Collarless sherds are more common at the Tara site. Collared sherds were more popular later in time than Collarless ones, so the Van Eden and Rife sites are the youngest. These graphs are sometimes called battleship graphs because the shape of each type looks like the outline of a battleship.