News

Large granite slabs uncovered in Trench 2

Posted by steven on 14/07/2005 at 02:18 PM


The excavations in Trench 2 on the High Pastures site are now in excess of three metres in depth, where two large granite slabs have been uncovered. Are these slabs the roof lintels for the former entrance into Bone Passage in the cave? Read on for more news of this discovery, progress in Trench 3 and links to the latest finds. 


After excavation of the hearth settings in the Trench 2 extension (see last news report) and removal of a low rubble wall, we have uncovered two large granite slabs. Above the slabs we recovered well-preserved animal bone deposits, shellfish remains and bone and antler pins (see Latest Finds Page for more details). The slabs, which are between 150 and 200mm thick and of substantial dimensions, have been set almost level and are fitted together with small gaps between them (see image below).

The image shows the Trench 2 extension with the uncovered slabs in the bottom (vertical scale = 0.5m sections/small scale on slabs is 0.25m), with the lenses of peat ash and charcoal-rich sediments visible in the section behind.

With hopes running high that what we had found was the roof lintels of a souterrain-type passage providing access to the natural cave beyond, we recorded the slabs and decided to remove the smaller of the two to have look below. What we found below was not what we had hoped for. Instead of finding an open or partially open passage, we found the granite slabs to be resting on large limestone boulders and smaller stones with a charcoal-rich sediment running between them.

The image above shows Martin and George lifting the smaller of the two granite slabs, with the chaotic fill of boulders, stones and sediments below.

The slabs have been levelled with the use of ‘pinning’ stones below, one of which had caused the larger slab to break down the centre. We therefore decided to remove one half of this slab to obtain a clearer picture of what was going on below, but again we were thwarted by the presence of the boulder fill. Somewhat frustrated by our findings under the slabs we excavated around the limestone blocks and stones of the fill, recovering a few bone fragments and shellfish remains in the process.  We also removed the stones that were not too heavy in the fill so we could progress downwards. Eventually, after excavating through a sediment layer full of charcoal fragments, we came down on to a quite natural layer of material that was gritty in texture and only contained the odd small fleck of charcoal.

The image above shows the Trench 2 extension with the remaining sections of level granite slabs in the bottom, disappearing into the north-facing section. Below the slabs the large limestone blocks and other filling material can be clearly seen giving way to the gritty brown silt.

If this was a section of a souterrain-type passage leading into the natural cave entrance then it has been thoroughly backfilled with material, preventing access from the time this process was carried out. We have similar parallels for the backfilling of Iron Age monuments such as souterrains in the archaeological record, such as at Newmills. The unusual monument investigated recently at Mine Howe in Orkney, which was originally excavated in the early 20th century, had also been backfilled with stone and sediments containing ‘domestic’ rubbish. Why these types of monument were subjected to this ‘permanent’ form of closure is not at all clear. Was there a change in religious belief and ritual practices?

Whatever the reasons for the backfilling of the passage at High Pastures, the results of our excavations to investigate this feature and gain access to Bone Passage in the cave through this former entrance will have to wait until next year. If the passage has been closed in this manner throughout its length, then we will have to open new trenches to enable us to get a clearer picture of the structures involved and to provide a safe route of access into the cave. Extending the existing trench to enable us to carry out these objectives will involve the removal of considerable amounts of material, containing complex archaeological deposits. Therefore, the planned work in Bone Passage will have to proceed this year using the existing entrance that was opened up in 1972.

However, work is not quite finished in Trench 2. We will be extending the east end of the trench to investigate the low stone-built wall and its relationship to the stratigraphy that lies below. This will also allow us a glimpse of any other structural evidence in this part of the site and hopefully to pick up the full extent of the compacted fire-cracked stone layers that were identified here.

The image above shows Trench 2 viewed from the west. The half of the trench sectioned on the right shows the natural limestone bedrock (white) and the karstic clay overlying this (yellow) falling away into the pit feature. The deep pit feature F204 was cut through sediments in this sector of the trench. Work over the next month will concentrate on removing the dark charcoal-rich contexts on the left side of the trench in this image, to investigate a possible pit or ditch feature that shows in the centre section. The extension to the trench can be seen marked by the upright and horizontal ranging poles, and will take in the small fragment of wall that shows in the section.

Work in Trench 3 has also progressed well during the past few weeks, although this trench has also been closed down now for this year. George Kozikowski has undertaken most of the excavations in this trench recently, which have been complicated due to the presence of substantial amounts of stone and boulder fill.

The trench, which was located to investigate the entrance of the stone-built roundhouse that is evident on the surface, initially picked up a pattern of large boulders that formed each side of the entrance. This feature was then sectioned and half of the trench was excavated to the present conclusion of work. During the excavations several sherds of prehistoric pottery was recovered from a brown soil that provided the matrix to the stonework and fill. This was followed by a few fragments of charcoal, fire-cracked stone and a few degraded pieces of animal bone and teeth. However, with depth the excavations uncovered a chaotic fill of boulders and stone, set in the same brown soil. Just one thin occupation horizon was found interupting the brown sediment, which shows as a dark charcoal-rich lens in the sections of the trench.

The image above shows the north-facing section of Trench 3 with the chaotic boulder, stone and brown sediment fill, punctuated by the thin charcoal-rich lens (horizontal scale=2m/small vertical scale=0.25m).

Eventually, at a depth of some 1.7 metres below the turf line George uncovered another feature in the trench, comprising a row of stones that may have provided some form of revetment at the edge of the pit feature identified in Trench 2. To the west of the revetment George uncovered thin lenses of peat ash and charcoal-rich sediments, which indicated that burning may have taken place in this location. However, with the exception of a few fragments of charcoal these deposits provided no further finds. The archaeological deposits to the east of the revetment was quite different in nature. Here, George recovered seven sherds of pottery (see Latest Finds Page for more details), large pieces of animal bone and significant deposits of charcoal. Sediments wet sieved from this area was found to be rich in charred cereal grains and burnt hazelnut shell.

The image above shows Trench 3 from above with the peat ash and charcoal-rich deposits in the foreground (scale=0.25m) and the row of stones forming the revetment just beyond. The pottery, animal bone and charcoal deposits were recovered from the deeper pit-like feature between the stones at the top of the picture. Quite different activities were obviously taking place in this small area of the site and it will be necessary to open up a larger area of the roundhouse next year to enable us to determine the wider use of the site in relation to the cave entrance and the activities that were taking place on site once this had been closed.

The area between Trenches 2 and 3 is showing a major change in the stratigraphy of the site, with well stratified deposits in Trench 2 and substantial amounts of dumped and chaotic fill in Trench 3. This transitional area of the site will be investigated further next year.

This image shows Trench 3 from the west with Trench 2 beyond. The section facing the camera shows the chaotic nature of the fill in this part of the site. The small scale (0.25m) is resting on the revetment stones, while the peat ash and charcoal-rich lenses have been removed in the foreground. The dimensions of the trench and the quantity of boulders in the fill has resulted in the closure of the trench until next year.



Next entry: Latest developments from the excavations at the High Pastures site

Previous entry: Hearth settings excavated in Trench 2


Comments
Posted by Coralie Mills on 25/07/2005 at 09:59 AM

A more general comment about the site. During a visit to local friends at Breakish, Martin Wildgoose & Steve Birch kindly offered to show us the site. We visited on 24th July 2005. I’m (Coralie Mills) an archaeologist by profession, and my husband Gordon Turnbull used to be. We were both impressed by the professionalism of the excavation, by the unusually deep, complex stratigraphy of the site and by the fantastic preservation. This is clearly a site of great importance for understanding the later prehistoric period in the Hebrides and beyond. Steve took us down into the cave, a fantastic experience and we saw some very intriguing deposits and beutiful formations. The above ground archaeology is also well worth a visit. We would encourage others to support this excellent project and to visit the site or follow the web-site developments.



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