Abstract
THE Geological Magazine for November (No. 101) commences with a note on the forms of valleys and lake-basins in Norway by Mr. J. M. Wilson, in which the author draws attention to a connection which he has observed between the configuration of the surface of the country and the disposition of the principal planes of division of the rocks, this disposition apparently altering with the windings of the valleys. His notion appears to be that masses of rock have been torn a way by glacier action until a divisional plane offering a minimum resistance to the passage of the ice was exposed.—The second article is the conclusion of Mr. Alfred Tylor—s paper on the formation of deltas and on the evidence and cause of great changes in the sea-level during the glacial period, in which the author describes at considerate length the structure of the Delta of the Po (which is illustrated by sections of numerous artesian borings in Venice), and refers also to those of the Mississippi, Ganges, and Volga, in support of his views as to the peculiar curves formed by the surface of these deposits, his hypothesis of the former occurrence of a general “Pluvial” period, and his belief that during the glacial period there was an actual subsidence of the sea, due partly to its contraction by cold and partly to the abstraction of large quantities of water to form the enormous deposits of ice and snow in the colder regions. He also indicates the curves produced generally by denudation and deposition.—Mr. John Hopkinson describes some new species of Graptolites from the South of Scotland, including representatives of the genera Dendrograptus, Graptolithus, Diplograptus, and Dicranograptus from the Llandeilo rocks of Lanarkshire and Dumfriesshire; and a species of the anomalous genus Corynoides from the latter district. This paper is illustrated with a plate.—From Prof. Hall, of Albany, we have a note on the relations of the Middle and Upper Silurian (Clinton, Niagara, and Helderberg) rocks of the United States, written in opposition to Mr. A. H. Worthen, and in support of the generally received opinions upon this subject. The paper, although to a certain extent controversial, furnishes a useful summary of this department of American geology.—Mr. H. B. Woodward publishes a note on the Midford Sands, which he seems inclined to regard as truly transitional between the Upper Lias and the Inferior Oolite, and from this takes occasion to hint that the Keuper, Lias, and Oolite; may be looked upon as one conformable series, the divisions or stages of which are to a certain extent arbitrary. The number concludes with the completion of Prof. Nordenskiöld's account of his expedition to Greenland in 1870.
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Scientific Serials . Nature 7, 133 (1872). https://doi.org/10.1038/007133a0
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DOI: https://doi.org/10.1038/007133a0