[2][3] Prehistory is conventionally divided into a number of shorter periods, but differentiating these various eras of human history is a complex task – their boundaries are uncertain, and the changes between them are gradual.
However, in general, the Paleolithic lasted until the retreat of the ice, the Mesolithic until the adoption of farming and the Neolithic until metalworking commenced[4] The Neolithic period's extraordinary wealth of structures is not matched by the remains from earlier periods, in which the evidence of human occupation is sparse or non-existent - nor is it matched by remains from the later Bronze Age, which provides a relative dearth of evidence.
Much of the North Sea basin was dry land until after 4000 BC, which would have made travel to northern Scotland relatively easy for early human settlers.
[6][7][8][9] The very limited archaeological record of this period provides scant evidence of Mesolithic life - in Orkney in particular and in Scotland north of Inverness in general.
"Lithic scatter" sites at Seatter, South Ettit, Wideford Hill, Valdigar and Loch of Stenness have produced small polished stone tools and chippings.
[14] About 6000 BC the Storegga Slides off the coast of Norway created a tsunami that reached 25 metres (82 ft) above normal high tides in places.
Evidence of widespread coastal inundations from a wave 8 metres (26 ft) high has been found as far south as Fife and the impact on shore-dwelling mesolithic societies in Orkney would have been considerable.
In the Orcadian context, there are definite developments during the Neolithic, but the changes are gradual and tend to build on earlier ideas rather than appearing to form two distinct periods.
However, recently discovered evidence shows that Orkney was the starting place for much of the megalithic culture, including styles of architecture and pottery, that developed much later in the southern British Isles.
Occupied between 3100–2500 BC the houses are similar to those at Barnhouse, but they are linked by common passages and were built into a large midden containing ash, bones, shells, stone and organic waste.
A variety of bone beads, pins and pendants and four carved stone balls were also discovered at the site, which was only revealed after a storm in the winter of 1850 ripped away the grass from a covering sand dune.
The original interior chambers were simple in style and dived into two or three stalls, but were later enlarged to include twelve separate compartments set along a 23 metres (75 ft) passageway.
[35][37][38] Enlargement and elaboration of burial cairns as the Neolithic progressed is a theme found throughout Scotland, and the move from simple and private tombs to larger structures, some with entrances apparently designed for public gatherings may also be linked to the emergence of landscape-scale ceremonial complexes.
[44] It is also clear that whilst the flow of ideas and technologies in Britain has often been from the south to the north, that at this time, it is evident that Orkney played a significant role in the development of British Neolithic culture.
Grooved Ware pottery on the other hand tends to be associated with larger 'village' settlements like Skara Brae and Barnhouse, and with Maes Howe style tombs.
[46] The grass mound hides a complex of passages and chambers built of carefully crafted slabs of sandstone that in scale and accomplishment has few equals in prehistoric Europe.
It is aligned so that the rear wall of its central chamber, a rough cube of 4.5 cubic metres (5.9 cu yd) is illuminated on the winter solstice.
[52][53][54] Excavations by Orkney College at the nearby Ness of Brodgar site between the Ring and the Stones of Stenness revealed several buildings, both ritual and domestic and the works suggest there were likely to be more in the vicinity.
Although containers of pigments have been found at sites such as Skara Brae, this was the first discovery in Britain, and possibly in Northern Europe, of evidence that Neolithic peoples used paint to decorate their buildings.
The first grooved pottery, which is so distinctive of the era, was made here, for example, and the first henges – stone rings with ditches round them – were erected on Orkney.
[70][71][72] The Dwarfie Stane tomb on the island of Hoy is made from a single huge block of red sandstone with a hollowed-out central chamber.
It was the first Orcadian ancient monument to be described in writing, appearing in the 16th century Descriptio Insularum Orchadiarum by Joannem Ben who provided the explanation for its existence as having been built and used by giants.
[78][79] In Orkney, fewer large stone structures were built during this period, burials were now being made in small cists well away from the great megalithic sites and a new Beaker culture began to dominate.
These are substantial stone towers that developed out of the roundhouse tradition in north and west Scotland, whose dry-stone walls may have reached 13 metres (43 ft) in height.
[89][90][91] Mine Howe, located near Tankerness in the parish of St Andrews, is a prehistoric subterranean man-made chamber dug 7 metres (23 ft) deep inside a large mound.
[103] As Roman influence waned in Scotland from 211 onwards,[104] Orkney faded from history again and the Celtic Iron Age way of life continued, largely unchanged.
The Buckquoy spindle-whorl found at a Pictish site on Birsay is an Ogham–inscribed artefact whose interpretation has caused controversy although it is now generally considered to be of both Irish and Christian origin.
Evidence associated with the St Boniface Church on Papa Westray suggests this island had been the seat of the Christian bishopric of Orkney in Pictish times.
F. W. L. Thomas, whose day job was as a captain in the Royal Navy, published The Celtic Antiquities of Orkney in 1852,[114] which listed various sites and aimed to interest "antiquarians" in the subject.
He was involved in excavations at Skara Brae and Rinyo, but it was only when a shard of pottery was discovered at the latter site that it became understood that these settlements dated to the Neolithic rather than the Iron Age.