Читать книгу The Clyde Mystery - Lang Andrew, May Kendall - Страница 7

It was in July 1898, that Mr. Donnelly, who had been prospecting during two years for antiquities in the Clyde estuary, found at low tide, certain wooden stumps, projecting out of the mud at low water. On August 16, 1898, Dr. Munro, with Mr. Donnelly, inspected these stumps, “before excavations were made.” 22 It is not easy to describe concisely the results of their inspection, and of the excavations which followed. “So far the facts” (of the site, not of the alleged relics), “though highly interesting as evidence of the hand of man in the early navigation of the Clyde basin present nothing very remarkable or important,” says Dr. Munro. 23

I shall here quote Dr. Munro’s descriptions of what he himself observed at two visits, of August 16, October 12, 1898, to Dumbuck. For the present I omit some speculative passages as to the original purpose of the structure.

“The so-called Dumbuck ‘crannog,’ that being the most convenient name under which to describe the submarine wooden structures lately discovered by Mr. W. A. Donnelly in the estuary of the Clyde, lies about a mile to the east of the rock of Dumbarton, and about 250 yards within high-water mark. At every tide its site is covered with water to a depth of three to eight feet, but at low tide it is left high and dry for a few hours, so that it was only during these tidal intervals that the excavations could be conducted.

On the occasion of my first visit to Dumbuck, before excavations were begun, Mr. Donnelly and I counted twenty-seven piles of oak, some 5 or 8 inches in diameter, cropping up for a few inches through the mud, in the form of a circle 56 feet in diameter. The area thus enclosed was occupied with the trunks of small trees laid horizontally close to each other and directed towards the centre, and so superficial that portions of them were exposed above the surrounding mud, but all hollows and interstices were levelled up with sand or mud. The tops of the piles which projected above the surface of the log-pavement were considerably worn by the continuous action of the muddy waters during the ebb and flow of the tides, a fact which suggested the following remarkable hypothesis: ‘Their tops are shaped in an oval, conical form, meant to make a joint in a socket to erect the superstructure on.’ These words are quoted from a ‘Report of a Conjoint Visit of the Geological and Philosophical Societies to the Dumbuck Crannog, 8th April, 1899.’ 24

The result of the excavations, so far as I can gather from observations made during my second visit to the ‘crannog,’ and the descriptions and plans published by various societies, may be briefly stated as follows.

The log-pavement within the circle of piles was the upper of three similar layers of timbers placed one above the other, the middle layer having its beams lying transversely to that immediately above and below it. One of the piles (about 4 feet long) when freshly drawn up, clearly showed that it had been pointed by a sharp metal implement, the cutting marks being like those produced by an ordinary axe. The central portion (about 6 feet in diameter) had no woodwork, and the circular cavity thus formed, when cleared of fallen stones, showed indications of having been walled with stones and clay. Surrounding this walled cavity – the so-called ‘well’ of the explorers, there was a kind of coping, in the form of five or six ‘raised mounds,’ arranged ‘rosette fashion,’ in regard to which Mr. Donnelly thus writes:

‘One feature that strikes me very much in the configuration of the structure in the centre is those places marked X, fig. 20, around which I have discovered the presence of soft wood piles 5 inches in diameter driven into the ground, and bounding the raised stone arrangement; the stones in these rude circular pavements or cairns are laid slightly slanting inwards.’ 25

From this description, and especially the ‘slanting inwards’ of these ‘circular pavements’ or ‘cairns,’ it would appear that they formed the bases for wooden stays to support a great central pole, a suggestion which, on different grounds, has already been made by Dr. David Murray.

The surrounding piles were also attached to the horizontal logs by various ingenious contrivances, such as a fork, a natural bend, an artificial check, or a mortised hole; and some of the beams were pinned together by tree-nails, the perforations of which were unmistakable. This binding together of the wooden structures is a well-known feature in crannogs, as was demonstrated by my investigations at Lochlee and elsewhere. 26 It would be still more necessary in a substratum of timbers that was intended (as will be afterwards explained) to bear the weight of a superincumbent cairn. Underneath the layers of horizontal woodwork some portions of heather, bracken, and brushwood were detected, and below this came a succession of thin beds of mud, loam, sand, gravel, and finally the blue clay which forms the solum of the river valley. 27 The piles penetrated this latter, but not deeply, owing to its consistency; and so the blue clay formed an excellent foundation for a structure whose main object was resistance to superincumbent pressure.

Outside the circle of piles there was, at a distance of 12 to 14 feet, another wooden structure in the shape of a broad ring of horizontal beams and piles which surrounded the central area. The breadth of this outer ring was 7 feet, and it consisted of some nine rows of beams running circumferentially. Beyond this lay scattered about some rough cobble stones, as if they had fallen down from a stone structure which had been raised over the woodwork. The space intervening between these wooden structures was filled up in its eastern third with a refuse heap, consisting of broken and partially burnt bones of various animals, the shells of edible molluscs, and a quantity of ashes and charcoal, evidently the débris of human occupancy. On the north, or landward side, the outer and inner basements of woodwork appeared to coalesce for 5 or 6 yards, leaving an open space having stones embedded in the mud and decayed wood, a condition of things which suggested a rude causeway. When Mr. Donnelly drew my attention to this, I demurred to its being so characterised owing to its indefiniteness. At the outer limit of this so-called causeway, and about 25 feet north-east of the circle of piles, a canoe was discovered lying in a kind of dock, rudely constructed of side stones and wooden piling. The canoe measures 35½ feet long, 4 feet broad, and 1½ foot deep. It has a square stern with a movable board, two grasping holes near the stem, and three round perforations (2 inches in diameter) in its bottom. On the north-west border of the log-pavement a massive ladder of oak was found, one end resting on the margin of the log-pavement and the other projecting obliquely into the timberless zone between the former and the outer woodwork. It is thus described in the Proceedings of the Glasgow Philosophical Society:28

‘Made of a slab of oak which has been split from the tree by wedges (on one side little has been done to dress the work), it is 15 feet 3 inches long, 2 feet broad, and 3½ inches thick. Six holes are cut for steps, 12 inches by 10 inches; the bottom of each is bevelled to an angle of 60 degrees to make the footing level when the ladder is in position. On one side those holes show signs of wear by long use.’

An under quern stone, 19 inches in diameter, was found about halfway between the canoe and the margin of the circle of piles, and immediately to the east of the so-called causeway already described.

I carefully examined the surface of the log-pavement with the view of finding evidence as to the possibility of its having been at any time the habitable area of this strange dwelling-place; but the result was absolutely negative, as not a single particle of bone or ash was discovered in any of its chinks. This fact, together with the impossibility of living on a surface that is submerged every twelve hours, and the improbability of any land subsidence having taken place since prehistoric times, or any adequate depression from the shrinkage of the under-structures themselves, compels me to summarily reject the theory that the Dumbuck structure in its present form was an ordinary crannog. The most probable hypothesis, and that which supplies a reasonable explanation of all the facts, is that the woodwork was the foundation of a superstructure of stones built sufficiently high to be above the action of the tides and waves, over which there had been some kind of dwelling-place. The unique arrangement of the wooden substructures suggests that the central building was in the form of a round tower with very thick walls, like the brochs and other forts of North Britain. The central space was probably occupied with a pole, firmly fixed at its base in the ‘well,’ and kept in position by suitable stays, resting partly on the stone ‘cairns’ already described, partly in wooden sockets fixed into the log-pavement, and partly on the inner wall of the tower. This suggestion seems to me to be greatly strengthened by the following description of some holed tree-roots in Mr. Bruce’s paper to the Scottish Antiquaries: 29