By degrees these repeated discoveries attracted the attention of antiquaries, and Dr. Pleyte, of Leyden, is now publishing a large illustrated work on the antiquities of Holland (B. 301), in which a conspicuous place is given to the terp-mounds and their contents. It is, however, to some of the office-bearers of the Museum of the Friesch Genootschap at Leeuwarden, more especially Mr. Corbelijn Battaerd, its conservator, that I am indebted for much of my information on the subject. In this museum are stored up most of the objects hitherto found in the terp-mounds, and the collection, already unique of its kind, is daily and rapidly increasing, as orders have been issued in regard to many of them that no relics are to be disposed of without being, in the first place, submitted to the authorities of the museum.
Like most countries, the early traditions of Holland have been forgotten or ignored, and in its annals little mention is made of the terpen. In explanation of the origin and early use of the word, Dr. Pleyte quotes from Ocko van Scharl a passage to the effect that one of the ancient kings of Friesland, named Adgillus, who reigned towards the end of the sixth century, had caused, on account of the ravages of an inundation which took place four years prior to his accession, a large number of elevated places to be formed, so as to give shelter to man and beast in the event of a recurrence of this danger. These mounds were then called Terpen.
Mr. Dirks, president of the Friesch Genootschap, as early as 1871 characterised these mounds as analogous to the terramara beds of North Italy ("ce sont des terramares historiques");[65] but it remained to Professor Pigorini of Rome to show that they were identical as regards internal structure. This he did in 1881 (B. 372c), after a visit to one at Aalzum which was then being excavated, when he showed that there was a circumscribing dyke, and, although no actual piles were then visible, he was informed by the proprietors that such wooden structures had been occasionally met with. Prior to his visit, it appears that no special attention was directed to these structural remains. From all he could learn, however, on this point, and especially from a consideration of the stratified arrangements of the débris, Pigorini concluded that the deposits were due to pile-dwellings, and had accumulated under precisely similar conditions to the terremare, in regard to which he is such a distinguished authority.
The terp at Aalzum is still being systematically excavated, and, though only as yet partially cleared off, its results, from an archæological point of view, are now second to none of the kind in Holland. Moreover, the excavations are conducted on an extensive scale, and the locality is readily accessible. I can, therefore, conceive of no better means of conveying to you some knowledge of the nature and structural phenomena of these remarkable deposits, than by detailing the facts which came under my own cognisance during a visit I made this summer to the same spot under the guidance of my excellent friend, Mr. Battaerd.
The terp lies about a mile to the north of the town of Dokkum, some twelve miles from Leeuwarden, and four or five from the seashore. In approaching the locality from Dokkum there was little to attract special notice beyond the usual Dutch scenery—canals, rich meadows, herds of splendid cattle, and here and there some well-cultivated cornfields. In front of us a slight elevation could be discerned, crowned by a small church in the midst of a clump of trees, the surroundings of which were neatly hedged meadows and cornfields. As we advanced towards this church, and within a few hundred yards of it, we entered on a sloping road, as if raised on a dyke, but on each side the land was perfectly flat and bearing a splendid crop: here a field of magnificent beans, and there an equally promising one of wheat. These fields, said Mr. Battaerd, were formerly part of the terp-mound from which the fertilising stuff has already been removed, but this road was left undisturbed, so that we are now actually walking on a portion of its surface. By-and-by we came in sight of heaps of clayey stuff, the tops of which sparkled with reflected light, and in their midst were to be seen the masts and rigging of three boats. Those whitish clay-like heaps, said Mr. Battaerd, formed the surface soil, which, being of no commercial value, had to be wheeled off before the saleable deposits could be got at. At last the actual workings were reached, and we found ourselves in front of a perpendicular section some 15 or 18 feet high, from which men and women were busily engaged in loading the boats. Uppermost in my thoughts was the paramount question of the existence of upright piles, which, it will be remembered, Pigorini had not actually seen. Great was my delight when, at the very first glance, my eye detected an undoubted pile of oak just in face of the cutting. Close by it I soon found another and as we moved along numbers were observed, some soft and yielding, scarcely offering any resistance to the spade; and others of oak very hard in the centre, but more decayed and ragged-like than those I have been in the habit of seeing among the lake-dwelling remains. Those seen in this section differed considerably in size; and I observed that some penetrated deeper than others. At a little distance lay a heap of oak beams which had recently been removed from the trenches—one of which I measured and found it to be four yards in length, and from six to eight inches thick. Upon inquiry, I ascertained that these beams lay horizontally, and about half way down, in the stratified stuff.
Those who, like Professor Pigorini, are acquainted with the structural features of the terremare of Northern Italy, will not be surprised at the comparative rarity with which piles are met with in the terpen, because of the rapidity with which timbers, when buried in dry earth, decay and disappear altogether, leaving in many instances no traces whatever behind them. This fact was strikingly shown by Chierici, who produced positive evidence of the former existence of piles in the upper strata of some of the terremare, by showing that the holes left by the piles, after the woody fibre had completely disappeared by decomposition, had become subsequently filled up by dust and infiltrated material, which ultimately became hardened, and so retained the actual form of the original piles. ([See page 248].) In short, natural casts of the original piles were accidentally formed, which thus disclosed a knowledge of their former existence, which otherwise might never have been suspected. To the soundness of this deduction I have myself unconsciously contributed by an observation which I made some years ago, while digging at the crannog of Lochspouts, and having recorded it I may perhaps be allowed here to repeat my words. "One day I was greatly puzzled by finding what was evidently a portion of a birch tree, from 6 to 9 inches in diameter, quite flat, and with scarcely any wood left inside the thick bark. In no instance previously had I seen the evidence of pressure on logs of this size; but after carefully considering the point it was ascertained that such effects occurred only in the upper portion of the mound, and above the log pavement, where the wood had been exposed to atmospheric influences, so that when the woody fibres rotted away the flattening of the bark was easily produced. All the logs found buried in water or mud retained their original dimensions and showed no trace of having yielded to superincumbent pressure."[66]
The absence of piles and wooden structures from many of these mounds is, therefore, no proof that they have not formerly existed; and, indeed, it is difficult to account for the horizontality and regularity of the beds on any other hypothesis.
While I wandered about amidst the various sections presented by the progressive stages of the excavations, wondering at the distinctness of the strata, or picking up stray objects from the débris, such as mussel shells, bits of bone, fragments of pottery, etc., which were to be found here and there sticking in the face of the cuttings, my friend, Mr. Battaerd, was deeply occupied in examining a heap of bones, which lay weathering in a sunny corner. Having joined him in his osteological study, I found that the chief point of attraction was the head of a urus (Bos primigenius) of great size, and with splendid horn cores—the finest example, according to Mr. Battaerd, that had yet found its way to the museum.
The land close to the brink of the section, and extending over a considerable portion of the mound, was occupied by growing corn, and hence its dimensions can only be approximately stated. The proprietors, Messrs. W. and J. Bierma, obligingly accompanied us, and one of them assured me it could not be less than from three to four hundred yards in diameter. Its greatest height above the water in the canal was 18 feet, but of course the level of the canal water is considerably lower than that of high tide in the open sea. The commercially valuable stuff commenced some 3 or 4 feet below the surface, and continued without interruption to within a few feet of the canal water. It was in this intermediate portion that the relics were found: but their exact position, especially that of the smaller objects, was seldom determined, as it was generally after the stuff had become partially broken up during transport that they were found.
The stuff in situ was distinctly stratified, forming layers of various thicknesses, from a finger breadth up to 3 or 4 inches, or sometimes more, which in some instances could be continuously traced for long distances. Sometimes they shelved out altogether, and others commenced. Here, a bed of fibrinous matter, in which quantities of the partly decomposed fibres of flax could be readily recognisable; there, a thickish deposit of a brownish glutinous stuff like peat. Charcoal and ashes permeated the whole, and showed themselves sometimes as distinct layers. Clay and sand were also largely mixed with these deposits, and occasionally assumed the form of distinct and separate beds.