Cairns and mounds usually conceal burial chambers and are directly related to the vast and complex area of relationships between the living and the dead. Although a lot of research still needs to be done in this area such monuments can be divided into different models depending on the type of tombs and their location in relation to local settlements.

Sealed tombs ("tumulated tombs") 

Cist graves under tumuli show a desire to physically "break off communication" with the dead. 
The volume of the tumulary mound or cairn may be seen as a clear sign of this intention (in order to prevent plundering or relic collecting as well as to protect the living against the return of the dead . 
The monument also provided a focus for cults designed to worship sacred persons who were no longer physically present. The "prestige artefacts" found in some of these sealed tombs, especially in the large "Carnacean" barrows, were part of the same process of mythification.
The excavation of Er-Grah barrow at Locmariaquer revealed the tumulus making process, at least in its main lines.
Next slide
Previous slide

"Open" tombs ("dolmenic" tombs)  

Unlike the tumuli, they consist of a system linking them to the outside world (a passage, a vestibule, an antechamber, and a door). Death is therefore seen in a different perspective. Bone remains often correspond to secondary deposits, showing a certain interaction between the living and the dead (or between the living and the relics materialising the memory of the dead).

The relative sizes of the chamber and of the entrance passages show that the dead had to be left in peace, relatively speaking, even though the living could be in contact with them (two extreme instances of this are the long-passage Middle Neolithic tombs and the Late Neolithic gallery graves ). 
The subdivisions of the chamber seem to indicate that funerary functions could be differenciated.

All types of Late Neolithic gallery-type tombs have extended chambers and smaller access structures as well as greatly reduced external structures. All that goes hand in hand with a change in funerary technique (i.e. more bodies but more individual treatment), which became the main reason for the existence of these tombs.

Art in megalithic tombs 

This kind of art illustrates the complexity of the sacred in Neolithic times. It is all the more difficult to study since many of the decorated slabs were reused in later monuments and buildings. 
Rock art is almost unknown inside "sealed" tombs, which were not designed to provide access to the living, but a few examples can be seen on menhirs. 

Two main cycles can be found:

  • the first, in the 5th and 4th millennia, evolved local styles typical of Gavrinis or Pierres-Plates;
  • the second, in the 3rd millennium, can be related to Late Neolithic gallery-type tombs.
Next slide
Previous slide

Exploded view of Gavrinis showing the small size of the chamber and the long passage leading to it at the heart of a square-shaped cairn covered with a rounded barrow.