- Portals:
Circumferential
or Unknown
Portals: Radial
There are two basic variants - those that have portal stones set with their long axes along the circumference of the circle like all the other stones and those with portal stones set radially, with their long axes perpendicular to the circumference of the circle.
Stone circles of the Cork-Kerry type are known as axial stone circles and always have an odd number of stones in their perimeter. Some may also have an internal monolith and some have an internal boulder-burial that has been added by a later group of people.
The axial stone is usually in the south-west quadrant and is normally the lowest, widest stone. Opposite the axial stone are a pair of portals and these are normally the tallest stones of the circle. The axis thus defined may be astronomically bi-directional or uni-directional in either direction. Stone circles of broadly similar type occur in North-East Scotland where they are known as Recumbent Stone Circles.
The two arcs of stones between each portal and the axial normally contain equal numbers of stones that grade downwards in height from the portals to the axial. However, variations in the height, spacing etc. of these side-stones may have been used to indicate secondary axes or other zones of interest on the horizon.
This sample represents about 48% of the known total at time of writing.