Their most striking characteristic is that in the general direction of south-southwest there is a large stone lying on its side with its length lining up with the perimeter of the circle.
Thought to have been from the Bronze Age, their unusual design, and the possibility of being associated with astronomical observations, has attracted several surveys starting at the beginning of the 20th century.
[1][4] Until the mid 19th century these circles, when they were noticed at all, were spoken of as being "Druidical Temples" or similar epithets and it was Frederick Coles who was the first person to carry out a systematic survey which he published in an annual series of papers from 1900 to 1907 in the Proceedings of the Society of Antiquaries of Scotland.
[12] In 2011 the Royal Commission on the Ancient and Historical Monuments of Scotland (RCAHMS) published an authoritative book, Welfare (2011), on recumbent stone circles specifically.
[13][14] The RCAHMS also issued an online gazetteer giving details of each monument that listed 71 as confirmed being recumbent[15] and another 85 as not belonging in this category.