The Geological History of the Thames is still the subject of conflicting hypotheses. Mr. F. W. Harmer (1907) has drawn a very interesting parallel between the basin of the Middle Thames around Oxford and the Vale of Pickering in Yorkshire. The latter, as is well known from Professor Kendall's paper (1902), was occupied by a glacial lake which was due to the Derwent River having had its outlet to the sea south of Scarborough closed by a dam of ice; the water rose in this lake until it overflowed at a gap near Malton; the river thus formed cut a gorge through which the drainage from the Vale of Pickering flows south-westward into the Yorkshire Ouse, and reaches the sea through the Humber. According to Mr. Harmer the Upper Thames originally discharged north-eastward through the Fens into the Wash; this outlet was blocked by the ice; the waters of the Upper Thames collected as a lake, which was discharged by overflow channels cut through the Chiltern Hills, and as the lake-level fell the discharge was maintained only through the Goring Gap at the south-western end of the Chiltern Hills. This view advances a different explanation of the Chiltern wind gaps than that advocated in a paper in 1894, and is opposed to the theory of the evolution of English rivers adopted by Professor W. M. Davis in 1895.
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page 147 note 3 Gregory, J. W., “The Evolution of the Thames”: Nat. Sci., vol. v, pp. 97–108, 1894.Google Scholar
page 147 note 4 Davis, W. M., “The Development of certain English Rivers”: Geog. Journ., vol. v, pp. 127–46, 1895.Google Scholar
page 148 note 5 Mr. Osborne White is also of the opinion that the excavation of the Goring Gap was begun in long pre-Glacial times.
page 148 note 6 Pocock, T. I., The Geology of the Country around Oxford, Mem. Geol. Surv. England and Wales, 1908, pp. vi, 142.Google Scholar
page 148 note 7 White, H. J. Osborne, “On the Origin of the High-level Gravel with Triassic Debris adjoining the Valley of the Upper Thames”: Proc. Geol. Assoc., vol. xv, pp. 157–74, pl. vii, 1899.Google Scholar The view that the clay with flints on the Buckinghamshire hills is of glacial origin has been maintained by Sherlock, & Noble, (Quart. Journ. Geol. Soc., vol. lxviii, pp. 199–212, pls. xii–xiv, 1912).CrossRefGoogle Scholar In the discussion on this paper the authors' views were generally rejected.
page 148 note 8 Salter, A. E., “Pebbly and other Gravels in Southern England”: Proc. Geol. Assoc., vol. xv, pp. 264–86, 1899.Google Scholar