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( 513 ) XXV.—Notice of High-Water Marks on the Banks of the River Tweed and some of its Tributaries; and also of Drift Deposits in the Valley of the Tweed. By DAVID MILNE HOME of Wedderburn, LL.D. (Plates XXXV.-XXXVIII.) (Read June 7, 1875.) A few years ago, a memoir on high-water marks on the banks of the Rivers Earn and Teith, in Perthshire, by the Rev. THOMAS BROWN, was read in our Society, and published in our Transactions. The only other Scotch geologist, so far as I know, who has alluded to the existence of river terraces, much above the level of existing floods, is the late Dr ROBERT CHAMBERS. In his work, entitled " Ancient Sea Margins," Dr CHAMBERS specifies many Scotch rivers, in the valleys occupied by which, he had seen terraces, at considerable heights above the rivers and above the sea. The explanations of these high river terraces given by the Rev. Mr BROWN and by Dr CHAMBERS respectively, are different. I venture to entertain doubts respecting the soundness of both explanations; and as the subject is of some interest, it appears to me that farther inquiry is desirable. Dr CHAMBERS was under the belief that almost all the high-level terraces examined by him on the Tweed, Tay, Clyde, and Spey, were horizontal, and therefore not formed by rivers. He did not suggest, that they had been formed by lakes. He considered them sea beaches. The Rev. Mr BROWN, on the other hand, states that all the high-level terraces which he examined on the Rivers Earn, Teith, and their tributaries the Turrit, Keltie, and Ruchil, slope with the streams; and he ascribes their formation to river action. He however came to this rather remarkable conclusion, that the highest of these terraces on the Earn, which is about 57 feet above the channel of the river, and in like manner the highest terraces in the other four rivers, had been formed by floods in these rivers, whilst flowing in their present channels; to account for which floods, he supposes the existence of what is called " a pluvial period " in Western Europe. The floods in the Earn now, seldom rise higher than 10 or 12 feet. A rise of the river in its existing valley, of 57 feet, certainly would imply a climate and state of things very different from the present. Startling as this conclusion appeared, I found that it had been also suggested by another geologist, Mr ALFRED TYLOR, in explanation of the high terraces of VOL. XXVII. PART IV. 6 U Trajvs. RoysL I So c. ECUJL !" REFERRED TO ON PAGES 517 AND 554 OF TF:XT. VOL PUN OF TWEED VALLEY FROM BERWICK TO KELSO SHOWING LINES OF TERRACES SCALE i T-H OF 6 INCH ORDNANCE MAP The Figures orv iJte Litter refer (AJ 'the, Text where, thus some Fiyures OCSMT* Henderside Paxton Village Lafiyterk Village Coldstream Town €aniy Bridge ICK UPON TWEED Sproii stok Village Cornhill Town W. & A.K.. Johnston.. Edinbaxgh. Fig l.(See page 526 of text) Preston Haugh. West -East Fig 2 (See page 943 of text) Oxendean Kaim. East . _"WTA AI. Johnsto A3AH0S 30NVMOaO IAIOUJ & 01 o 82 L_ PLATEXXXVJI1 Bxjyah ,>'<*>. Tnui.s. VIU. XXVII. VALLEY OF TWEED FROM SEA TO SUMMIT LEVEL AT MOSS PAUL AND ST. MARYS LOCH TO SHOW DIRECTION OF DRIFT RIDGES. Heights zrv -feet' above' the- l&'el ofth&Seatikas 373 :&A.K..iohr.f.i.nr'.l , 514 D. MILNE HOME ON HIGH-WATER MARKS ON THE the Eiver Somme in France, a river apparently about the same size as the Earn and Teith. In the Somme valley, there are beds of fluviatile gravel, at the height of about 80 feet above the present channel of the river; and these beds, Mr TYLOR maintains, were deposited by the river in its present channel rising to that height when in flood. It occurred to me, that some test of the correctness of these views might be obtained by an examination of similar high terraces visible in the valley of the Tweed. I had a good opportunity of making this survey, having long had my residence on the north bank of the river, and being therefore well acquainted with the locality. I shall also in this memoir describe some other things in districts adjoining the Tweed, which seem to be more or less connected with the formation of the terraces. I divide my paper as follows :— 1st, Notice of the Eiver Tweed, between Melrose and Berwick. ; 2d, Notice of districts adjoining the River Tweed, dd, Theoretical explanations. 4th, Views held by other persons. I,—Eiver Tweed and its Banks. 1. The channel of the Tweed at Melrose, is about 270 feet above the sea, and about 30 miles distant from the sea. The towns of Kelso and Coldstream divide the course of the river into three parts, each part being about 10 miles long. The levels of Kelso and Cold- stream, above the sea, show that between Melrose and Kelso, the gradient or fall of the river is at the rate on an average of 17 feet per mile; between Kelso and Coldstream, of 7 feet per mile; between Coldstream and Berwick, of 3 feet per mile. The diagram fig. 1 represents these several gradients. Fig. 1. B, Mouth of Tweed at Berwick; C, Tweed atTColdstream; K, Tweed at Kelso ; M, Tweed at Melrose. That rate, however, is on the assumption that the river runs from one point to another in a straight line. If in consequence of its windings, 60 miles in- stead of 30 be assumed as the length of its actual channel, the rate of fall per mile would be very much less. BANKS OF THE TWEED AND SOME OF ITS TBIBUTABIES. 515 The neap tide comes up the river to the Chain Bridge, about 5 miles from Berwick, and the spring tide about 2 miles higher up. The banks of the river along its course differ in height and in distance from one another, as in most rivers. Where the river passes between hard rocks, the banks are high, the width between them small, and the stream generally deep ; when not deep, it is rapid. Where the river passes through soft strata,—such as marl, clay, gravel, or sand,—the banks are low, with a greater width of stream. The terraces or flats noticeable along the course of the river, exist chiefly on the kind of banks last described. The stream wears away and undermines detrital materials more easily than rocks; so that marks are most frequently on banks of detritus. 2. The first flat or terrace with its bounding cliff which I notice, is the lowest in level, and therefore the most recent. The base of this cliff was reached by a flood which occurred on 9th February 1831. It has not, since that date, been again reached. There had previously been two floods in the memory of persons still alive— one called the Boiler Flood,* and the other, the Berwick Fair Flood,—neither, so remarkable as that in 1831. The fact of this flood of 1831, having risen higher than any previously known, accounts for the circumstance that, at about twenty different places between Melrose and Berwick, individual proprietors, apparently without mutual con- cert, thought it right to mark, some by stones, others by brass plates, the precise height to which the flood reached on their lands or houses. The following table indicates the height above the present ordinary summer level of the river, to which the flood of 1831 rose. Places. Height. Remarks. Feet. Berwick, . 15 Pointed out by harbour master. New Water Haugh, . 13 Given by gardener, being a mark made on a tree. Whitadder Mouth, f . 12 or 13 Base of lowest visible cliff. Whitadder, Cant/s Bridge, 12 Do. do. Gainslaw, 19 Water rose up two steps of lobby in farm-house. * I have not learnt in what years, these two previous floods occurred. The Eoller Flood takes its name from the circumstance that a large wooden roller for farm purposes, lying on Leeshaugh, near Coldstream, was lifted by the flood, carried down to the mouth of the river, and stranded on Spital beach. Having been recovered, it was sent back to Lees. Probably this flood occurred in October 1797, the year in which Kelso Bridge was swept away. The Berwick Fair Flood is supposed to have occurred in the month of May,—that being the month of the principal fair at Berwick. Mr JEFFREY, in his " History of Roxburghshire," mentions that a flood occurred in the Teviot in the year 1846, which was greater than that in 1831. In the Tweed, this flood did not rise so high as that in the year 1831. t Near the junction of the Tweed and Whitadder, a considerable change has visibly taken place in the course and levels of both rivers. The Ordnance Survey Map indicates that the Tweed below 516 D. MILNE HOME ON HIGH-WATER MARKS ON THE Places. Height. Bemarks. Feet. Yard Ford, 15 Base of lowest visible cliff. Start Fishery, . 18 Do. do. Tweedhill, 21 Marked by a stone with inscription. Chain Bridge, . 20i Marked by an iron bolt put into north pier. Field, west of do., 23" Marked by a stone with inscription. Horncliff (east of), 22 Base of lowest cliff. Horncliff (west of), . 20 Do. do. Norham Castle (opposite to), 23 Base of lowest visible cliff. Upsetlington Boathouse, 23 Mark on window of boat-house. Milne Graden, . 23 Marked by a stone still standing below garden.

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