Published online by Cambridge University Press: 01 May 2009
The following investigation was undertaken not only with a general descriptive aim, but also to endeavour to ascertain how far correlation of isolated plutonic outcrops can be made by means of the study of the accessory minerals. It is in addition an attempt to supply further evidence bearing on the relative ages of the Jersey granites and diorites in view of the opinion of Dr. G. H. Plymen, based on field evidence, that the granites are of two ages, but both Pre-Cambrian, the Mont Orgueil and Gorey granite being the older.
page 242 note 1 The presence of ilmenite has in each case been confirmed by a chemical test for titanium made on the material picked up by a large horseshoe magnet.
page 244 note 1 Brammall, A., Proc. Geol. Assoc., vol. xxxvii, 1926, p. 251;CrossRefGoogle Scholar Min. Mag, vol. xx, 1923.Google Scholar
page 245 note 1 Hatch, and Wells, , Text-book of Petrology, vol. i, p. 433.Google Scholar
page 245 note 2 The amount of rock crushed in the case of each specimen was never less than about a quarter of a pound; in exceptional cases five or six times this quantity was crushed.
page 245 note 3 For the complete list of minerals from each locality refer to the table.
page 246 note 1 Plymen, G. H., Proceedings Geologists' Association, xxxiii, 1921, p. 166.Google Scholar
page 247 note 1 It should be noted that apatite is present in the Fort Regent mass.