Silbury Hill is a 40-metre high man-made mound near Avebury in the English county of Wiltshire.
It is the largest man-made earthen mound in Europe. There are many Neolithic monuments in the area, including the West Kennet Long Barrow and Stonehenge.
Structure
Composed principally of chalk excavated from the surrounding area, the mound stands 40 metres (130 feet) high and covers about 5 acres (2.2 hectares). It is a display of immense technical skill and prolonged control over labour and resources. Archaeologists calculate that Silbury Hill was built about 4750 years ago and that it took 18 million man-hours, or 500 men working 15 years (Atkinson 1974:128) to deposit and shape 248,000 cubic metres (8.75 million feet³) of earth and fill on top of a natural hill. Euan W. Mackie asserts[3], that no simple late Neolithic tribal structure as usually imagined could have sustained this and similar projects, and envisages an authoritarian theocratic power elite with broad ranging control across southern Britain.
The base of the hill is circular and 167 m (550 feet) in diameter. The summit is flat-topped and 30 m (100 feet) in diameter. A smaller mound was first constructed, and in a later phase much enlarged. The initial structures at the base of the hill were perfectly circular and surveying reveals that the centre of the flat top and the centre of the cone that describes the hill, lie within a metre of one another.
The first phase, carbon-dated to 2750 BC, consisted of a gravel core with a revetting kerb of stakes and sarsen boulders. Alternate layers of chalk rubble and earth were placed on top of this, the second phase involved heaping further chalk on top of the core, using material excavated from an encircling ditch. At some stage during this process the ditch was backfilled and work was concentrated on increasing the size of the mound to its present height using material from elsewhere.
Purpose
The exact purpose of the hill is unknown. Moses B. Cotworth stated at the beginning of the twentieth century that Silbury was a giant sundial to determine seasons and the true length of the year. More recently, the writer Michael Dames has identified Silbury Hill as the winter goddess, but he acknowledges that the monument remains finally a stupendous enigma.
According to legend, this is the last resting place of a King Sil, represented in a lifesize gold statue and sitting on a golden horse. A local legend noted in 1913 states that the Devil was carrying an apron of soil to drop on the citizens of Marlborough, but he was stopped by the priests of nearby Avebury. In 1861 it was reported that hundreds from Kennett, Avebury, Overton and the neighbouring villages thronged Silbury Hill every Palm Sunday.
Michael Dames put forward a composite theory of seasonal rituals, in an attempt to explain Silbury Hill and its associated sites (West Kennet Long Barrow, the Avebury henge, The Sanctuary and Windmill Hill), from which the summit of Silbury Hill is visible.
Paul Devereux observes that Silbury and its surrounding monuments appear to have been designed with a system of inter-related sightlines, focusing on the step several metres below the summit. From various surrounding barrows and from Avebury, the step aligns with hills on the horizon behind Silbury, or else with hills in front of Silbury, leaving only the topmost part visible. In the latter case, Devereux hypothesises that ripe cereal crops grown on the intervening hill would perfectly cover the upper portion of Silbury with the top of the corn and the top of Silbury coinciding.