Structural Description (part 11)

Sediment Deposits within the Peripheral Wall

The sediment deposit accumulated artificially is an integral part of the monument, along with the central platform and the peripheral wall. This remark is important for the restitution of a general picture of the monument: in fact, and most probably, the central platform was invisible in past time, hidden by the artificially accumulated soil deposits; the only visible structural part of the monument was the peripheral wall and the probable lines of prayer flags surrounding it. The best way to show this is to present the cuts we documented during the second campaign (Fig. 37 and Fig. 38) (see also Fig. 11 for detailed placements of the cuts; cuts 3 and 4 are located outside of the main excavation area).

Fig. 37

Fig. 38

Cuts 1 and 2 run from the eastern platform flank through the eastern peripheral wall and outwards through the scatter of collapsed stones. Cut 1 was observed from the north and cut 2 from the south. While the sediment deposits located outside of the peripheral wall are arranged in a simple manner reflecting partly natural deposition processes, the succession of deposits between the peripheral wall and the platform show a high complexity. Our sedimentologist, Luc Braillard, who described the deposits on-site, distinguished four sedimentary units in cut 1 (Fig. 37: 1). The three upper deposits (suR1, suR2, and suR3) are interpreted as having an anthropic origin – they were accumulated by the builders at the end of the construction of the monument. The lower unit (su4) is the excavated ground on which the monument is built. In cut 2 (see also Fig. 39), the base unit su4 is overlaid by two naturally accumulated layers, one of which (su2.1) being a heavy slope deposit with a thickness attaining 1 meter in some areas, the other (su2.2) being the result of synchronic washing and natural slope deposition.

Fig. 39

Cut 3 (Fig. 37: 3) was made about 10 meters to the north-northeast of the northern peripheral wall. The goal was to ascertain the sediment deposition in the slope overlaying the monument, in an area left untouched by the historical builders. The cut presented four sedimentary units including the same compact yellowish brown-gray silt deposit (su4) found at the base of the monument. Above it, the natural soil is composed of a 60 cm thick brown humic layer (su2) and a thin vegetal decomposition layer (su1).

Cut 4 (Fig. 37: 4) was also made for testing the natural sediment deposition in vicinity of the monument, but in an area located to the southeast. Over the silt base su4, the brown soil su2 is 70 cm thick and can be divided in two sub-units (su2.1: colluvial, recent; su2.3: colluvial, old). The vegetation litter atop su2.1 is about 4-5 cm thick.

Cut 5 (Fig. 37: 5) is running parallel to the eastern peripheral wall of the monument. It shows the massiveness of the colluvial slope deposit su2.1, the regularity of the washing deposit su2.2, the natural slope of the underlying silt deposit su4, and finally it gives a glimpse of the shape of the mound in which monument B3 was concealed until 1998.

Cut 6 (Fig. 38: 6) runs through the southern peripheral wall. Although this cut is not reaching the base deposit su4, it shows the contact between the remains of the ruined peripheral wall and the sediment accumulated artificially behind it (usR1 and usR3). This cut also indicates that the monument underwent a strong erosion, and probably also endured important stone removal, along its southern fringe along which the stones are ultimately below today’s grass surface. Local informants told us that this area was known to give back a dump echo when the ground was hit with the foot. This certainly was because of the collapsed stones lying under the grass.

Cut 7 (Fig. 38: 7) also runs through the southern peripheral wall and could not be observed down to the base sediment su4. As in cut 6, observations confirm the strong erosion that occurred along the southern flank of the monument.

The last cut documented is cut 8 (Fig. 38: 8). It was made perpendicularly to the western peripheral wall and features a clear view through the collapsed stone scatter and associated deposits.

A detailed description of all sedimentary units in each stratigraphic cut can be found as appendix at report end.

As we can judge from the brief description of each cut, the deposits which are the most difficult to interpret are located between the peripheral wall and the central platform. In cut 1 (Fig. 37: 1), we see that the accumulation is a complex admixture of three sedimentary units (suR1, suR2, and suR3). The vertical succession of the layers shows the following chronological order: R1–R2–R1–R3–R1–R3–R1–R3–R1. This intricate situation and the composition of each unit indicate that the accumulation occurred in a very short lap of time, almost simultaneously. The units R2 and R3 originate from the digging of the pit that received the platform chamber. The unit R1 results most probably from a mix between the topsoil layer and yellow silts from su4. The sub-horizontal, but intricate, arrangement of the accumulation is also a sign of artificial deposition, as well as the fact that the R-units stop strictly against the eastern peripheral wall and cannot be found eastwards (Fig. 37: cut 2).

All observable facts bring us to the conclusion that the monument builders accumulated the massive sediment deposits located within the peripheral wall. This accumulation is part of a scheme that included the intentional fill of these areas and the covering of the central platform in order to hide it from view. In the following figure, we present a summary of the stratigraphic setting (Fig. 40).