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
( 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.
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