so that the smallest are to be found opposite the recumbent. The recumbent and its flankers were evidently seen as the most important elements of the circle; in a number of cases the remaining stones were added later, and in some cases were apparently never added at all. Irish stone circles Irish recumbent stone circles take a rather different form, with the recumbent being small and placed in an isolated position on the southwest side while the two tallest stones, known as portals, stand opposite on the northeast side. It is highly likely that the recumbent stone circles of northeast Scotland and south-west Ireland are related, given how similar they are, but the geographical distance between them – several hundred kilometers of mountain terrain, bogs and sea – has prompted debate about how exactly the relationship came about. It is possible that rather than there being direct communication between the two locations, the ideas underlying recumbent stone circles were transmitted by a single influential person or group of people who – for whatever reason – left one location and perhaps settled in the other. Because of the differences in design they are now more commonly called Cork–Kerry or axial stone circles. Usage Recumbent stone circles are believed by some archaeologists such as Aubrey Burl to have been designed for ritualistic astronomical purposes. The moon would have appeared above the recumbent stone, framed between the flankers. Scotland's recumbent stone circles have an average diameter of about , so a recumbent stone that was long would have given an observer an arc of vision of around 10 degrees. This would have given the worshippers about an hour during which the moon would pass over the stone. About every eighteen and a half years, the moon would make a closer approach in which it would appear to be "framed" between the two flanking stones above the recumbent; this was presumably a peak time for ceremonies. The nature of the ceremonies is unknown, but Burl suggests that "the rites enacted in the rings were closely connected with the flourishing and dying of plants, crops, animals and human beings in the short-lived world of four thousand years ago." The interiors of some excavated recumbent stone circles have been found to contain pits filled with charcoal, sherds of pottery and the cremated remains of human bones (sometimes those of young children). However, they were not funerary