These chambered tombs are the most numerous and important megalithic monuments in Galicia. They were places of collective burial, although the acidity of the Galician soil prevents any bony remains from arriving until today. But they not only fulfilled this function but they were used as markers of a certain territory that distinguished the community that had raised them, reason why they are located in elevations or near streams of water.
It is convenient to stress the absence of covered galleries in the Galician constructions. Those are a Catalonian feature and are usual in some places of Andalusia. In the gallery graves a clear differentiation between the chamber and the passage is not observed.
Now, and in a simple way, we classify the Galician dolmens, although it is the archaeologists job to do a more complex systematization as exist burial types in which the bodies were deposited directly on the ground, without any covering above or covered by an only stone that supported the barrow.
Galician dolmens show among them several differences:
When this sort of megalithic constructions have been excavated grave goods have been found and among them predominate the arrowheads, the sheets of flint, the microliths, the beads of variscite and some small pottery remains. They were erected about the year 4,000 B.C.
They appear during the second stage of the evolution of these buildings; This stage goes from circa 3,500 B.C. to circa 2,700 B.C. They are the most beautiful forms of the Galician megaliths. They generally have a polygonal ground plant although in some cases they are rounded polygonal chambers. In Galicia splendid examples are conserved, like the one of Dombate (Fig.2).
The pasage is many times covered and clearly higher compared with the megalithic chamber as it happens in the Casa da Moura in Queguas (Ourense) or in the Casa dos Mouros in Vimianzo (A Coruña).
Grave goods are similar to those found in dolmens of the previous phase, although the polished tools evolve towards more complex forms and the pottery remains are more abundant.
They represent the latest period, the final phase of the Galician megaliths. These monuments fall within the interval of 2,700 B.C. to 2,000 B.C. They usually have a rectangular ground plan and only one covering stone.
Beautiful examples of this sort of monuments are the Casota de Berdoias in Vimianzo or Fornela dos Mouros in Laxe (both in A Coruña), of which the plan appears in figure 3.
They are standing stones hard to date, with a ritual function that we are far away from understanding. Very little remains today and only two of them seem to be authentic: the Lapa of Gargantáns in Moraña (Pontevedra) and the standing stone of Cristal in Ribeira (A Coruña).
In order to establish the time of construction the best thing is to verify if they are in connection with dolmens, because in many occasions they are just marker stones or way points in crossroads, although they could be erected in very ancient times.
Their presence in Galicia is practically nonexistent. The archaeologist Federico Maciñeira presented in l894 two circles that were set in A Mourela in As Pontes (A Coruña). They were destroyed some years later to take advantage of their stones to make the surface of a road nearby. The bigger one (see drawing) was 20,5 m in diameter and consisted of small stones between 30 and 60 cm in height. Its entrance , oriented towards the southeast, was flanked by two quartz blocks of almost a meter high.
At present only one circle stone is considered authentic, the one located in O Freixo in As Pontes (A Coruña), because most of the investigators consider that the circle of Prao das Chantas in O Valadouro (Lugo) is a more modern accomplishment.
The modern dating methods like radiocarbon, the dendrochronology or the Termoluminiscense have allowed us to establish the Galician megalith phenomenon within the interval of the year 4,200 to the year 2,000 B.C, that is to say, in a period between the neolithic and the end of the calcolithic.
The analysis of the paleosoil that can be studied during an excavation is a mean of establishing the diverse aspects of the existing vegetation at the time of the construction of the megalithic monuments.