Published online by Cambridge University Press: 01 May 2009
The purpose of this paper is to discuss methods by which the data of sedimentary petrology (mineralogical composition, grainsizes, etc.) may be most usefully recorded upon a map. The ultimate aim which the writer had in mind when commencing this work was to learn something of the palaeogeography of North-East Yorkshire during Middle Jurassic times.1 It soon became evident, however, that a map upon which the data have been registered may be a record not only of the conditions at the time of deposition but also of the subsequent mineralogical changes in the rocks themselves and, what was less expected, of the tectonic development of the region as a whole.
page 417 note 1 The strata dealt with in this paper are those lying above the Dogger and below the Cornbrash; that is to say not quite the whole of the Middle Jurassic or Lower Oolites as usually denned.
page 419 note 1 Such mixed samples should be valid for much of the cartographic work, but they would not have been valid for most of the work described in Parts I and II.
page 424 note 1 Geol. Mag., LXXIV, 1937, 281–3.Google Scholar
page 424 note 2 Geol Mag., LXXVI, 1939, p. 357.Google Scholar
page 425 note 1 Measurements of minerals such as garnet, which are not found over the whole area, are unsuited for this purpose.
page 426 note 1 Geol. Mag., LXXVI, 1939, p. 309.Google Scholar