Structural Description (part 4)

Excavating the Chamber

Since we initially worked toward a dismantling of the platform, we wanted to secure all information about precise location of the stones we had to remove to excavate the chamber covering and filling. All the removed stones were numbered with synthetic paint ( Fig. 16 ) and secured under a plastic sheet next to the excavation area.

Fig. 16

This type of monument was being explored for the first time, so we had no idea about the content of the chamber. It was necessary to progress with caution, and R. Blumer took over the responsibility of this specific task. The excavation went through six stages, corresponding to six removed layers of filling material. Although filling differences were noticed during the excavation process, no peculiar deposit succession could be followed in the limited working area and artificial layers were thus removed. Moreover, the area was regularly filled with rainwater at campaign’s end, making progression and observation sometimes difficult.

During the first stage (excavation layer d0), we removed many of the superficial stone belonging to the chamber covering ( Fig. 17 a) and obtained a rough surface. Once cleaned in excavation stage d1, the obtained surface ( Fig. 17 b) still showed some flat stones in sloping positions, especially along the chamber flanks; we removed most of these in the subsequent stage d2 ( Fig. 17 c). During the subsequent stages d3, the last sloping stones along the flanks of the chamber were removed and the obtained surface was exclusively made of a dense accumulation of filling stones and sediment. We progressively removed this fill during excavation stages d3 ( Fig. 17 d), d4 ( Fig. 17 e), and d5. In the final stage, we obtained a clear picture of the emptied chamber itself, with its hardened and flat sediment floor ( Fig. 17 f).

Fig. 17

The deposits found in the chamber fill are heterogeneous in composition. We could distinguish three levels within the fill of the chamber: (1) in the upper 20-40 cm, the chamber covering is made of at least three concave layers of flat stones, mostly quite large in dimension (up to 80 cm long) with interstitial brown silty sediment; (2) below the covering, the composition changes to a mixture of stones (rounded and angular boulders) of medium to small sizes, intermingled in a denser brown silt deposit; (3) near the chamber floor, we have a 10-25 cm thick layer showing less stone density and a higher compaction degree of the brown-yellowish clayey silt. The flat chamber floor itself is made of the same compacted ground sediment as the deposit on which the platform is built (sediment unit 4).

The crosscut figures give detailed insight about the chamber filling composition and about the construction mode. The first shows the thickness of the deposits we excavated in the five last stages d1 to d5 ( Fig. 18 ). In this crosscut, we distinguish a small pit at meter 2.8; this corresponds to a test made from the surface of obtained after stage d4 to acknowledge the remaining thickness of the chamber filling. The following illustration is the same crosscut as Fig. 18 , but with added vertical stone scatter ( Fig. 19 ). Due to the recording technique we used (digital photographs with measured altitudes), we could not reproduce all the filling stones, but only those we can clearly observe on the pictures. This means that more stones were present than the ones that we could illustrate here. The last drawing is the same crosscut through the platform, but this time with reported elevation of the eastern chamber wall ( Fig. 20 ). It clearly shows the use of vertical slabs (here we distinguish vertical elements V6-V10) supporting the horizontal stones that constitute the platform itself. It also clearly indicates how the construction is adapted to the sloping ground on which the platform is built. For comparative reference, we can compare this view to the illustration of the western platform flank ( Fig. 13 , top). All three preceding crosscuts show that the southern wall of the platform is a little thinner (90 cm) and higher (110 cm) than the northern one (100 cm thick and 40 cm high)), but also built much higher (110 cm).

Fig. 18

Fig. 19