Circular worlds

The three henges at Thornborough were aligned along a north-west to south-east axis, stretching out over a mile. Each one is about 250 metres in diameter.

Like other henges across Britain, the Thornborough henges are each surrounded by an earthen bank. The banks at Thornborough originally stood up to 4 metres high, and were broken by two opposing entrances. We know from excavations that these inner banks were probably plastered with gypsum, a mineral dug from nearby pits, which would have made them a striking brilliant white.

Each henge had a deep and wide ditch inside the bank, defining the circular central area. Outside the main bank was a shallower and more uneven outer ditch, with a corresponding small outer bank.

Today the henge earthworks are eroded and have been damaged by quarrying and ploughing. The northern henge is relatively well preserved, however, as its dense tree cover has protected it from intensive agriculture. Its surviving earthworks show the impressive scale of the monuments when they were first built. The inner ditch is still up to 2.6 metres deep and some 20 metres wide, and the main bank survives up to 3 metres high and 18 metres wide.

Worlds above and below

The henge monuments at Thornborough were built in open, dry grassland on an upland plateau with extensive views of the sky. The high banks of each henge would have blocked views of the surrounding landscape for people standing within them, except through the entrances. It has been suggested that these entrances were aligned with the movement of particular stars, such as Sirius, the sky’s brightest star in the constellation Canis Major. Its rising would have been framed within the southern entrance of all three henges.

The southern entrances of the northern and central henges are also aligned with the midwinter solstice sunrise. This was part of a wider practice of orientating Neolithic monuments to the solstices, including the passage tomb at Newgrange in Ireland and the stone circle of Stonehenge in Wiltshire.

It has been suggested that the white gypsum covering the henge banks may have been associated with the underworld, with the bones of the dead, or with the bright stars above. The fact that the Thornborough henges were built in one of the most subsidence-prone parts of the Gypsum Belt, where natural sinkholes and hollows are common, underlines the association with the world below. This active and unusual geological landscape may be one of the reasons people built monuments here.

Bronze Age burials

In the early Bronze Age (about 2400–1500 BC), the Thornborough henges remained important, with several round barrows – mounds that usually covered graves or burials – built nearby. Between the central and south henges is a low mound known as the Centre Hill. When the archaeologist WC Lukis opened it in 1864, he found fragments of human bone in a wooden ‘coffin’ with a pottery vessel and flint tool. This was probably an early Bronze Age burial, although geophysical survey suggests that this barrow might have been built over an earlier, Neolithic structure.

Ten further early Bronze Age burial mounds and several ring ditches (circular ditches, usually surrounding a burial) are scattered across the landscape, including a group of three at Three Hills Group. Their upstanding earthworks have been destroyed by ploughing.

Also probably of this date are two double alignments of pits, which would have held timber posts, near the henges. Excavations at the one near the south henge have shown that it was 350 metres long, and probably erected between 1800 and 1600 BC. These ‘avenues’ may have been built to guide people’s movements, or make links between monuments. The southern avenue ends near a round barrow.

A threatened landscape

By the mid 20th century sand and gravel extraction had destroyed about 13 hectares (32 acres) of land around the Thornborough monuments, including areas within 600 metres of the central and south henges. This resulted in the loss of many archaeological features, including most of the main cursus monument. The cursus had only recently been discovered by JK St Joseph through aerial photography, and was not protected by law. Rescue excavations were only possible at the western terminal in 1955 before it was destroyed.

More recent extraction quarries at Nosterfield and Ladybridge to the north of the complex were much larger, covering nearly 182 hectares (450 acres). However, this time archaeological excavation and recording preceded the quarrying. This led to many new discoveries including Neolithic pits and scatters of flint – evidence for a settlement contemporary with the henges.

The earthwork henges have suffered in other ways: the central henge was used as a munitions dump during the Second World War, and a section of the south henge bank was deliberately bulldozed in the 1960s.