The stone is greywacke, a type of sandstone composed of tightly cemented mineral grains and rock fragments.
A single serpentiform motif with seventeen bends is picked across the stone using a variety of rounded points. At the right end, the motif curves downward briefly along the edge of the stone.
Knowth Kerbstone K91
Knowth Stone Age Passage Tomb
Knowth is a Stone Age Passage Tomb in the Boyne Valley and with
Newgrange and Dowth makes up the
Brú na Bóinne UNESCO World Heritage Site. Knowth is the largest passage tomb of the Brú na Bóinne
complex. The site consists of a large mound (known as Site 1) and 17 smaller satellite tombs.
The mound is about 12 meters (40 ft) high and 67 meters (220 ft) in diameter covering about
1 hectare (2.5 acres). It contains two passages placed along an east-west line and
was originally encircled by 127 kerbstones of
which 124 are still in place.
Knowth Passage Tomb Aerial View
The large mound is estimated to date to around 3200 BCE, placing it in the Late Neolithic period.
The passages are independent of each other, each leading to its own burial chamber. The eastern passage opens into a cruciform chamber,
comparable in form to that at Newgrange. It contains three recesses with basin stones into which cremated human remains were placed.
The right hand recess is larger and more elaborately decorated with megalithic art than the others, a feature characteristic of the eastern chamber at Knowth.
The western passage ends in an undifferentiated chamber, defined by a widening of the passage rather than a fully developed cruciform plan.
This chamber is separated from the passage by a sillstone and originally contained a basin stone, which was later removed and is now located approximately two thirds of the way back along the passage.