In 1891 I brought before the Society a paper on the beds of gravel which occur on the hills and in the valleys of the district south of the Thames between Guildford and Newbury. In that paper I drew particular attention to the composition of the gravel, and showed that gravel of a very uniform character extends in some cases over a considerable area (in one case over a length of nearly 10 miles), whereas other gravels in the near neighbourhood have different and yet curiously persistent characteristics. These peculiarities seemed so difficult to explain, on any theory which attributed the formation of the gravels to the action of the sea, that I arrived at the conclusion that they were river-gravels—their peculiarities of composition depending upon the geological structure of the drainage-areas of different rivers.
Sir Joseph Prestwich appears to have been inclined to the same conclusion. He says, writing in 1890:—
‘As the channels of the early streams became deeper and larger, and the Lower Greensand more exposed, the mass of débris carried down increased, and the proportion of chert and ragstone became greater. It was then that were formed the extensive plateaux of gravel of the Chobham and Frimley Downs, and of the other hills we have named in Berkshire, Hampshire, and Surrey.’
With this I quite agree, but in the next paragraph Sir Joseph says, ‘We are without a clue as to whether fluviatile or marine action had to do with their origin’; but, he continues,‘ but
The following communication is intended as a supplement to a paper read before the Society by one of the authors in 1883 (Quart. Journ. Geol. Soc. vol. xxxix. p. 348), and the two together form an amplification of an article on the same subject by Mr. W. H. Herrics (Geol. Mag. dec. ii. vol. viii. p. 171).
In our last paper we devoted our attention almost entirely to the Upper and Middle Divisions of the Bagshot series. We now propose to treat more fully of the Lower Division, and to show that the occurrence of pebble-beds is by no means confined to one horizon in the Bagshot series, as would seem to be supposed by some observers.
In the interval much has been written about the geology of the Bagshot district, no less than five papers by the Rev. A. Irving, and one by Mr. Hudleston, having appeared.
The views lately advanced by Mr. Irving are very much at variance with the hitherto accepted interpretation of the geology of this district, and to a great extent we find ourselves compelled to differ from him. He considers (Quart. Journ. Geol. Soc. vol. xli. pp. 506, 507) that the Upper and Middle Bagshot beds, in some places, overlap the Lower Bagshot Beds, and rest directly on the London Clay, which had been thrown into a slight syncline previous to the deposition of the Lower Bagshot strata. He founds his argument partly on the relative thicknesses of the Lower Bagshot beds and the
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