Overview of the Table-des-Marchands excavation: the megalithic chamber and passage structure in the centre of the cairn damaged by quarrying.

Excavations directed by J. L'Helgouac'h uncovered the base of an oval cairn approximately 30x25m wide.

It is bordered by a drystone masonry face and its internal arrangements include only a second face, subcircular and 18 to 20m wide, tangent to the other at the entrance of the passage.

This monumental structure (which may have been 5 to 6m high) seems to have been broken up as early as the Gallo-Roman period, in order to provide loose stones (taken from the cairn) and ashlars (uprights from the dolmen) for the nearby settlement.

Like all the other monuments of this site, the Table-des-Marchands dolmen was not built on virgin soil; under the monument and in the immediate vicinity, untouched fossil soil revealed a great deal of pottery sherds and flints from the Middle Neolithic, several fireplaces, "pit-quarries" attacking the rock and many "post holes" evidencing wooden structures from the second half of the 5th millennium BC.

The dolmen and its cairn were probably erected at the very beginning of the 4th millennium BC, when the alignment related to the Grand-Menhir had most probably already disappeared.