[Footnote 44: The writer gratefully acknowledges his indebtedness to Prof. Lapworth for some of his views concerning deposition of strata.] [Footnote 45: The lines 1, 2, 3 ... are incorrectly drawn in the figure. Line 1 should be drawn so as to separate _a_, _b_, _c_, _d_ from _a_^{1}, _b_^{1}, _c_^{1}, _d_^{1}, line 2 to separate _a_^{1}, _b_^{1}, _c_^{1}, _d_^{1} from _a_^{2}, _b_^{2}, _c_^{2}, _d_^{2}, and so with the others.] If elevation ceased and were succeeded by depression, the exact opposite would occur, and the pebble beds would be overlain by sandstones, these by muds, and lastly limestones would appear. It follows that during a marine phase occurring between two unconformities we should have a =V=-shaped accumulation of deposits with the apex pointing to the part of the shore line which was last submerged before the commencement of elevation, as shewn in fig. 14, though the beds of the apex will in most cases be denuded during the re-emergence. [Illustration: Fig. 14.] Indications of the non-coincidence of the planes separating faunas and those which separate deposits of one lithological character from those of another have already been detected, for instance the 'greensand' condition of the Cretaceous period occurs in some places during the existence of one fauna, and in others during that of another, though the planes have not been traced continuously. Mr Lamplugh has furnished another example amongst the Cretaceous rocks of Yorkshire and Lincolnshire, but as has already been observed, a great deal remains to be done in this direction, and geologists are much in want of two sets of stratigraphical maps, in one of which the lines are drawn with reference to the differences of lithological character, whilst in the other they separate different faunas. The student will notice the normal recurrence of deposits in definite order; conglomerate succeeded by sandstone, mud and limestone, in a sinking area, and limestone succeeded by mud, sandstone and conglomerate in a rising area. Naturally many instances of departure from this rule are seen, owing to local conditions, but on a large scale, it is very frequently noted, and recognition of this will enable the student to remember the variations in the lithological characters of the deposits more easily, than if he simply acquired them from a text-book without taking heed as to their significance.