﻿24 Notices of Memoirs — J, S. Gardner's Lecture — 



them attentively there is, it seems to me, a very well marked and 

 recognizable sequence. I will now indicate the sequence. It 

 has never been laid before the geological public until now, and it is 

 possible, as is often the case with new work, that there may 

 be some objections raised to it. I can only tell you, however, that 

 after discussing the matter with geological friends, my own con- 

 victions are strengthened." The author then referred to his diagram 

 of the district. " This lower fresh-water series is seen in the neigh- 

 bourhood of Corfe, and forms part of the cliffs at Studland. It is 

 characterized by abundance of pipe-clays, and forms a thickness of 

 possibly 200 feet. The middle fresh-water series, also met with 

 near Corfe and at Studland, forms the whole thickness of the cliffs 

 between Poole Harbour and Bournemouth. We thus have a mag- 

 nificent section four miles long and 100 feet in height. Branksea 

 Island is also formed of this series. Their entire thickness cannot 

 yet be accurately estimated, but may be put down at some 300 feet. 

 They are characterized by the fact that the clays contained in them 

 are usually brick-earth. 



The next series above is a marine series, and is some 400 ft. or 

 500 ft. thick. The base beds are dark sands and clays, succeeded by 

 pebble beds and sands, then more sandy clays with pebbles, and 

 ending with a thick deposit of white sands. This marine portion of 

 the series occupies the cliffs between Boscombe and High Cliff. It 

 is the middle fresh- water series which is so rich in the clay beds 

 containing fossil leaves. These leaves are found in various con- 

 ditions of preservation. In most cases the impression only of the 

 leaves in the clay is met with, but in some cases they are so well 

 preserved that the actual substance has been retained, although chemi- 

 cal changes have altered its composition, and it will peel off and 

 blow away. In some of the clays the masses of leaves are so decayed 

 that they cannot be recognized, and are not worth our collecting. 

 Where the preservation is good, we can readily distinguish the 

 various original textures of the leaves by comparing their general 

 aspect and colour both among themselves and with existing forms. 

 For instance, those which are thick, such as evergreens ; thin, as 

 convolvulus ; hard, such as oak ; or soft, such as lilac ; or even 

 velvety, such as the common Phlox, can all be recognized. Their 

 colours, in most of the beds, vary from buff to brown, and I need 

 hardly tell you that in no case have we any of the green colouring 

 of the leaves preserved. Whilst these various shades of dark buffs 

 and browns are in many cases the result of chemical change that has 

 taken place after the leaf was covered up, yet I believe that in many 

 cases this change had occurred, at least partially, before the covering 

 up, just as we saw a few weeks ago the changed colours of the fallen 

 leaves of autumn. In the darker clays the remains are black and 

 completely carbonized ; where this is so, the finer venation is indis- 

 tinct and the remains difficult to save, so that we may discard them 

 unless the outline of the leaf is of unusual form. The darker browns, 

 I take it, indicate hard and evergreen leaves ; for instance, the 

 laurel-like leaves are always of a deep colour, whilst both the thin 



