Typically, the chamber is larger than a cist, and will contain a larger number of internments, which are either excarnated bones or inhumations (cremations). Most were situated near a settlement, and served as that community's "graveyard".
Scotland has a particularly large number of chambered cairns, many of radically different type. Because of the lack of other remains (the only other significant remains we have are Hut circles and field systems), they are perhaps the most important clue we have to what civilisation in Scotland was like in the Neolithic. Here is a short description of each type as the classification currently stands:
The Clyde-Carlingford group are to be found in both Scotland and Northern Ireland. On the Scottish side, they are mainly found in Argyll and Dumfries and Galloway, both in the south-west of the country (a small outlying group can be found near Perth). They are not passage-graves in the traditional sense since they lack any significant passage; the chamber (although usually blocked after use) is of very basic design and is normally located at one end of the cairn. As a result, it can be accessed from the outside. These cairns are generally considered to be the earliest in Scotland, dating from 4000 BC and were probably brought to Scotland from Ireland.
Sharing some features with the Clyde-Carlingford group is the Hebridean group. As their name suggests they are normally found in the Hebrides, and have a crude polygonal chamber and a very short passage to one end of the cairn.
The Orkney-Cromarty group is by far the largest and most diverse. It has been subdivided into Yarrows, Camster and Cromarty subtypes but the differences are extremely subtle. In general, they all have dividing slabs at either side of a rectangular chamger, separating it into compartments. The number of these compartments ranges from 4 in the earliest examples to over 24 in an extreme example on Orkney. The actual shape of the cairn varies from simple circular designs to elaborate 'forecourts' protruding from each end, creating what look like small Amphitheatres. It is likely that these are the result of cultural influences from mainland Europe, as they are similar to designs found in France and Spain.
The Bookan type is thought to be the earliest to be found on Orkney. Because of Orkney's archaeological richness, Bookan type tombs are very hard to find. They are extremely unusual, some being double-deckered! They all seem to have features which suggest some early stage in the development of Maes Howe type tombs.
The Maes Howe group, named after the famous monument on Orkney, is among the most elaborate. Like their counterparts on Shetland, they are unlike anything else in Scotland, so it is possible these were the result of local development, or influences from Scandinavia. They consist of a central chamber from which lead small compartments, into which burials would be placed.
Finally, the Shetland group, of which little is known. On plan, they do look similar to the Maes Howe group although the whole chamber is cross-shaped and there are no small compartments.Chambered cairns in Scotland