The key result of the 1998 excavations at Prissé-la-Charrière was the discovery that the western end of the monument contained an earlier structure or structures, flanked by their own quarry ditches, which had been overlain by the later enlarged long mound. This discovery provided the main focus for the work which was carried out in 1999, and which was in large measure designed to clarify the nature of the earlier structures and their relationship with the later phases. For this reason, excavation in 1999 was concentrated primarily at the western end of the mound, and notably in and around the western chamber revealed in 1998. The programme of work included examination of the junction between the dry-stone structures surrounding the western chamber and the mound built up against it to the east, characterised by its massive core of yellow material. On the southern flank, excavations begun in 1998 were pursued in 1999 so as to expose the in situ structures (notably the system of alveoles). Similar work was undertaken on the northern flank, and excavation here was extended to include sections across the primary quarry ditch at the foot of the mound. The purpose of these quarry sections was to study the fill of the quarry and its relationship to the outer and inner kerbs which were built across it when the mound was enlarged during the later phase.

The leading conclusions from this fifth season of excavations at Prissé-la-Charrière may be summarised as follows:

1. The principal constructional elements are now much more clearly defined. There are at least four major units laid end to end along the long axis of the mound: beginning at the west with (a) the dry stone structures associated with and including the two ‘inclined walls’ and the ‘massif’ surrounding the western chamber; then (b) the huge deposit of yellow material composing the core of the early long mound; next (c) the passage grave; and finally (itself consisting perhaps of more than one such ‘unit’) (d) the eastern half of the mound.

The flanking quarry ditches running beneath the edge of the enlarged mound suggest that in some sense units (a) and (b) belong together as two halves of a single structure; likewise, the passage grave (c) may prove to belong with the eastern section of the mound (d). It is equally important to note that within each of these ‘units’ there is the possibility of multiple phasing, with modification, extension and rebuild.

2. This evidence translates directly into the multi-phase character of the mound. At its simplest this can be seen as a division into two phases: an earlier phase marked by a long mound 25m long, with flanking quarry ditches to either side and a sealed western chamber; and a later phase in which the early mound was buried within the western end of a much longer mound, 100m long and up to 20m wide, with broader quarry ditches set back some distance from the foot of the mound.

A further element in this bipartite scheme is the difference in construction between the two phases: more informal in the earlier phase, with massive dumps of material in places, articulated by spine and spur walls; and a later phase when construction took the form of a honey-comb of cells or alveoles, providing greater stability to the monument. This could be seen as a result of greater local understanding of mound construction, and the development of new constructional techniques designed to avoid slumping and collapse.

That this two-phase scheme is over-simplified can be shown in the contrast between units (a) and (b), described above. Tip lines within the yellow material of unit (b) indicate that it was deposited against the eastern face of the dry-stone unit (a) (more specifically, against the massif and its flanking lengths of wall), and that deposition proceeded in an eastward direction. Hence the primary phase appears within itself to subsume at least two separate phases. Examination of the intersections between the dry-stone walls at the western end, in unit (a), also suggest that a number of different phases are represented. Within this scheme must also be accommodated the basal kerb lines on the northern side of the mound, buried beneath later deposits and running adjacent to the inner edge of the primary quarry.

The suggestion is that, rather than a scheme which envisages two principal phases, the mound is to be envisaged as a multi-phase structure, with the overall configuration and the intentions of the builders developing piecemeal as each element was added or modified.

3. The burial feature within the western end consisted of a chamber, defined by five modest-sized orthostats within a circular dry-stone massif, opening to the east, but without passage: instead, the entrance opened onto a funnel-shaped approach through the thickness of the wall. This eastern opening was closed at its inner end by a moveable limestone ‘door’. The walls flanking the chamber entrance are curved so as to form a slightly concave façade, and we may envisage this as the original eastern front of the monument, with the opening to the chamber at its centre. Only later was a blocking wall added across this opening so as to close the chamber. Sealing was completed by the heaping against this façade of the yellow material of the early long mound.

Such a chamber, with temporary entrance arrangements (but no passage), later blocked and buried within the enlarged mound, appears for the present to be without close parallel in this region, though it finds analogues among the Carnac mounds of southern Brittany.

The absolute chronology of this western chamber must wait upon the Oxford AMS dates currently in progress. Within the relative sequence of the structures at the western end of the mound, however, it clearly occupies a primary position. We may indeed speculate that it was the original burial focus from which the Prissé-la-Charrière long mound took its origin, and from which it developed through a lengthy process of addition and enlargement. It would be dangerous to press this hypothesis too strongly as other early structures may still lie waiting to be discovered beneath other sections of the mound, notably at the eastern end. It should be noted that (with the exception of the disturbed area around the ruined passage grave), it is only at the western end that the lower height of the mound has made it practicable to excavate down to bedrock and to establish what lies at the base of the structure. The dimensions of the mound, especially towards the taller and larger eastern end, make it difficult to execute deep soundings or systematically to penetrate through the later dry-stone structures in order to determine whether earlier phases lie beneath them, though such is highly probable.

What is beyond question is that the western chamber represents an important discovery, and is probably the nucleus from which the primary phases of the western mound developed. The absence of a passage would qualify it for an early place in the development of monumental funerary architectures in western France. Whether it does indeed belong to such an early stage in this development, before the adoption of the passage grave, will, we hope, become clearer once radiocarbon dates on the skeletal material are available.