Page:Quarterly Journal of the Geological Society of London, vol. 27.djvu/324

 cards arranged in order, 1, 2, 3, and so on up to Knave, Queen and King ; so that by their marks we should always be able to mention the cards above and below any given number, unless it happened that one or more had been surreptitiously abstracted from their places. The lacustrine, as distinguished from marine formations, do not strictly follow this rule.

Discussion.

Mr. Etheridge thought the question of the nature of the Rhaetic beds was to a great extent palaeontological. The main point in connexion with them was as to how the British beds were to be connected with those of the Lombardic and Middle European areas. It certainly seemed probable that in this part of the world the conditions of life were different, the deposits being much less in thickness, and the fauna much diminished ; and where represented at all the shells occurred in a dwarfed and stunted form. The exact horizon and nature of the Sutton beds had still to be determined.

Mr. Godwin- Austen believed that every mass of red sandstone would ultimately be referred to either a brackish or freshwater origin. A comparison of the ancient and present area of the Caspian Sea would tend to remove any doubt that might remain on the mind of geologists as to the possibility of the existence of such vast internal seas as those which had to be called in to account for these formations. He regretted that former observers had not attached more importance to the duration and extent of those freshwater conditions which were found so commonly to have prevailed between the periods of deposit of the great marine formations. There was another fact to be borne in mind, that even in existing lakes the water at the one end was sometimes completely fresh, and at the other end salt, each of course with a different fauna.

Prof. Rupert Jones said that although there were good grounds for the lake-theory, something might be said for shallow seas. He remarked that sulphate of lime was deposited from sea-water before salt, that oxide of iron might originate from chloride of iron diffused in water whether of lakes or seas, and that the haematites of Permian age were probably deposited in the sea. He considered that Foraminifera required great caution when used as criteria, as the varietal forms giving the facies were of more importance than the genera and species. The Estherioe were never marine, although often occurring in plenty in temporary freshwater pools on the seashore. In his monograph of Estheria he had said much to substantiate the notion that freshwater conditions often prevailed during the formation of the Keuper. Both in the Old Red Sandstone of the Baltic provinces and in the Lettenkohle and Keuper of Germany, when Estheria comes in, Lingula dies out. The repeated set of formations in the Permian and the Trias precludes their contemporaneity, as supposed by Messrs. Godwin-Austen and Marcou.

Mr. Bauerman remarked that the Hallstatt beds which had been cited as marine contained large deposits of rock-salt.