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II.—Ball or Pillow-form Structures in Sandstones1

Published online by Cambridge University Press:  01 May 2009

Extract

The structures described below occur in rocks of a rather monotonous and generally uninteresting type; namely in sandstones, interstratified with masses of shale and mudstone, exposed near the centre of the Berwyn Anticline in parts of Denbighshire. The necessity, however, of examining every exposure, incumbent upon the Surveyor, has led me to pay attention to detail, and especially to certain phenomena that would appear to be of world-wide occurrence in sediments of all ages.

Type
Original Articles
Copyright
Copyright © Cambridge University Press 1916

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References

page 148 note 1 For this reason the rock is unsuitable for use in the exposed corners and angles of buildings. It is known locally as ‘grinsel’.

page 151 note 1 Contrast ‘mud-lumps’, where mud is squeezed out from between sand-stones that are of different composition and grade of material (see later, p. 155).

page 152 note 1 The Upper Keuper Sandstones of East Nottinghamshire”: Geol. Mag., 1910, pp. 302–11.Google Scholar

page 154 note 1 The Upper Keuper Sandstones of East Nottinghamshire”: Geol. Mag., 1910, pp. 306–7.Google Scholar

page 154 note 2 On the application of Quantitative Methods to the Study of Rocks”: Q.J.G.S., vol. lxiv, pp. 171233, 1908.Google Scholar

page 154 note 3 I have recently seen ball structures in the sandstone of St. Bees Head, Cumberland, and Dr. R. L. Sherlock tells me that pillow-form masses of Magnesian Limestone overlie puckered Marl Slate in a cutting at the north end of Annesley Tunnel in Nottinghamshire.

page 155 note 1 The mud-lumps at the mouths of the Mississippi, by E. W. Shaw, U.S.G.S., Professional Paper 85-B, 1913.