Monument record 1744 - ALLT CHRISAL, BARRA

NL69NW 7.09 6376 9769.

T70: A rock shelter perched 20m above the Sound of Vatersay and the same distance from the shore-line. It was formed when an erratic in the form of a massive angular slab of gneiss was deposited onto an ice-smoothed surface, on which it slipped down-slope, becoming wedeged on four small blocks and fractured, leading to the formation of troughs and then rifts, and further collapse and slide. The end result was a low-roofed rock shelter with three small chambers, separated by the supporting blocks of gneiss. The westernmost chamber (i) measured 3.2m by 1.5m deep and had no soil accumulation on its floor. Chamber (ii), the middle one, measured 4.5m by 1.5m deep, with a subsidiary rear chamber, 2m by 1.4m, behing the supporting block. A very shallow deposit of silty soil lay over part of its floor. Its ceiling, however, was only 0.9 - 1.2m high and it seems unlikely that it was, or could have been, used for any purpose other than the most temporary of shelters. Chamber (iii), the easternmost was 4.5m by 2.5 - 3.2m deep, and had a ceiling at 2m. A rear, subsidiary chamber to the E was 3.5m by 2m, but only 0.8m high.

Immediately in front of the three chambers, a steep, smooth rock surface drops away sharply for a height of 6m, before the slope lessens to form a narrow platform above the sea.

Excavation in June 1989 was conducted in chamber (iii). Even here, surface indications suggested that there was very little depth of soil, and a trench 3m by 1.5m was laid out along the front of the chamber, immediately above the steep rock face below the shelter; it was subsequently extended to 4m by 2m. Beneath a layer of sandy peat, an uneven deposit 10-20cms thick of gritty or dandy brown silty soil had accumulated from which was recovered a single sherd of coarse handmade pottery. This deposit, which was found over the entire area of the trench, covered an L-shaped alignment of angular stones which in places survived two courses high and two stones wide. The largest stones used to built the alignment were 30-40cms in length and the two arms of the structure were 2.2 and 1.3m long respectively. beneath the silty soil was a thin deposit 2-3cms deep od peaty sand which was confined against the angle of the L, and which rested against the stones of the alignment. This deposit rested on a naturally cobbled surface which appeared to be the E edge of a talus formed of solifluction material. Outside the alignment, to the W, a 15cms wide band of darkish brown soil flscked with charcoal lay alongside the stone alignment, and immediately on the cobbled surface. The only other deposits found in the area excavated were the fill of two small but deep depressions on the very southern edge of the trench (and therefore of the shelter). Seven small pieces of flint were found in the south-eastern depression.

The interpretation of the deposits suggests the following sequence of events: Some time after the creatioin of the rock shelter, a low L-shaped stone wall was erected in the chamber, forming a windbreak, protecting an area from westerly winds, which could have provided a very well protected sleeping area for one or two persons. A soil began to develop while the shelter was in use, and in particular a pit-like depression just outside the shelter filled up after the wall was erected but before it fell into disuse. The flints from this deposit give the only indication for the date of the windbreak's construction and use. It is suggested that the flints most probably derived from an earlier assemblage at Allt Christal (NL69NW 7.37). Subsequently, the shelter fell out of use, the windbreak collapsed, and a silty soil developed over the floor of the shelter, during which time there may have been casual usage perhaps indicated by the single sherd of (neolithic?) pottery found in this material, but there is no evidence of any further regular or prologed interest in the shelter. Two shotgun cartridges found in the topsoil perhaps characterise fleeting and irregular usage of the shelter after its initial utilisation, which was probably in the neolithic.

An exploratory trench, 2.5m by 1m, was excavated running from the foot of the steep slope below the shelter towards the shore-line, to assess whether the platform immediately above the sea had been utilised or whether material washed out from the rock shelter might have accumulated there. In the event, there was no evidence of either occupation or washed-down deposits on the platform.
K Branigan 1989a; K Branigan and P Foster 1995; NMRS MS/595/3.

K Branigan, 1989a, Discovery and Excavation, Scotland, 68 (Bibliographic reference). SWE10408.

K. Brannigan & P. Foster, 1995, Barra: archaeological research on Ben Tangaval from the end of the Ice Age to the Crofting Commissio, 38, 165-7, 200, 201 plan: fig. 5.4 (Bibliographic reference). SWE33223.