have produced important information on the date and development of the Sarn-y-bryn-caled cursus complex between 3000-2000 BC. In particular a timber circle of 2000 BC, two penannular ring-ditches and a section across the cursus monument were excavated. A radiocarbon sequence has been obtained. The results of the excavations are described in Part I. Part II comprises a discussion of the forms, dates, functions, and reconstruction of timber circles. A corpus of and chronology for timber circles is presented. PART I: THE EXCAVATIONS 1 Clwyd-Powys Archaeological Trust,