Page:Quarterly Journal of the Geological Society of London, vol. 27.djvu/212

 observed in a summer ramble, from which, however, the following general conclusions may be rawn.

(1) That along the South Coast of England the Chalk Marl thins westward from the Isle of Wight, Where it is in good force, and its bottom part becomes marked, in that direction, by the presence of quartz-grains, mostly very small, but sometimes as large as a pea, showing perhaps signs of a less deep-sea character than usual in the deposit. This bottom bed is the most constant part westward, where, indeed, it seems sometimes to be all that represents the Chalk Marl.

(2) That along the South Coast the Lower Chalk, of no very great thickness in the Isle of Wight (about 200 feet perhaps), thins westward until in Devonshire it is but 30 feet thick, and occasionally less.

(3) The consequent nearness of the Upper Chalk (with flints) to the Greensand helps to explain the occurrence of the great deposits of flints on the hills of the latter in Devonshire.

Discussion.

Mr. Etheridge pointed out the resemblance between the series described by the author and that of the Chalk of Antrim. He thought it probable that the Cretaceous beds had originally extended over the whole of Western England. He called attention to the Blackdown beds, which had been regarded as Upper Greensand, but certainly were not so, though probably Cretaceous, as well worthy of examination.

Mr. Hull hoped that some Fellows of the Geological Society would extend their examination of the Chalk into Ireland, and visit the Antrim district. It was the case there that the Chalk with flints rested immediately on the Upper Greensand, though there was an intermediate band known as the Mulatto-bed, which might possibly represent the Chalk-rock.

Prof. Morris thought the paper afforded evidence in favour of the Chalk having been deposited in a sinking area, and during the process various alterations in the conditions took place.

Mr. D. Forbes inquired as to the character of the nodules mentioned, and whether they were siliceous or not.

Mr. Meter mentioned that near Branscombe there occurred a band within 8 feet of the Red Marl, containing fossils apparently the same as those of Blackdown.

Mr. Whitaker had purposely avoided characterizing the greater part of the Greensand-beds as either Upper or Lower. He thought the cherty beds of the west were stratigraphically higher than those of the Isle of Wight. The nodules inquired about were not siliceous, though probably containing some silica, but were rather phosphatic.