Radiocarbon dating of a
red deer antler pick discovered at the bottom of the western terminal ditch suggests that the Stonehenge Cursus was first constructed between 3630 and 3375 BCE. It is just under 3 km long, and is roughly 100 m wide. Because of a slight difference in the alignment of its north and south ditches, it widens to a point nearly 150 m near its western end. It is roughly aligned east–west and is oriented toward the sunrise on the spring and autumn
equinoxes. There is a (later)
Bronze Age round barrow inside the western end of the enclosure, and a large Neolithic
long barrow was constructed at its east terminal. The
Stonehenge Riverside Project excavated the remains of the long barrow in 2008 to determine if the barrow predated, or was contemporary with the cursus itself. The ditches of the cursus are not uniform and vary in width and depth. The eastern ditch is fairly shallow, as is the southern ditch – being only 0.75 m deep and 1.8 m wide at the top. At the western terminal, the ditch is 2 m deep and 2.75 m wide. Like most cursuses, its function is unclear, although it is believed to be ceremonial. The length of the cursus, running roughly east west, crosses a dry river valley known as Stonehenge Bottom. This may have been a
winterbourne during the Neolithic era. If so, this would give it similar characteristics to other cursus, such as the
Dorset Cursus, and it may be related to a ceremonial function. It has also been suggested that the Stonehenge Cursus acts as a boundary between areas of settlement and ceremonial activity. The cursus is also aligned on the equinox sunrise which rises over the eastern long barrow. Two artificial pits have been found near the east and west ends of the cursuses. It has been found that lines of sunrise and sunset at midsummer through these pits are aligned with
Stonehenge. ==Excavation==