59 
ON THE MICEOSCOPICAL EXAMINATION OF SOME 
BRACKLESHAM BEDS. 
By T. Rupert JoifES, F.G.S. 
In Yol. I of the ' Geologist,' at page 249, was published a paper 
on the preparation of sands, clays, and chalk, for microscopical pur- 
poses, under the heading of " Geological Manipulations ;" and, as 
both pleasure and geological profit are to be obtained from the exact 
examination of various fossil-bearing deposits, both as to their con- 
stituents and their contents, I beg to offer you an example of the 
results of such an examination of some tertiary beds from Brackle- 
sham. These notes I have had by me several years, and their short- 
comings are so great in some respects that I should not send them, 
were it not that they may serve as a plan to some youug care- 
ful observers who might feel inclined to enter upon the strict exa- 
mination of some definite series of fossilil'erous strata. AYhat the 
series under notice is deficient of, is a statement of the exact rela- 
tionship of these several deposits, examined nearly twenty years ago. 
I received the materials at that time from a friend who was collecting 
" Brackleshara fossils," — a term wliich will be more definite, now 
that the Rev. O. Eisher, E.G.S., has indicated tlie exact limits of the 
Bracklesham formation.* 
The specimens were chiefly, I believe, from Bracklesham and 
Selsea ; but some may have been brought from the Isle of Wight. 
By the presence of certain fossils, however, in some of the deposits, 
their exact place may probably be determined. However deficient 
in these stratigraphical requirements the following account of the 
deposits may be, they will serve the purpose here intended, namely, 
to show young beginners what to look for in sands and clays. In- 
structions have been already given as to liow such materials are to 
be examined, in the first volume, p. 249. 
The careful microscopical examination of a good series of succes- 
sive deposits, in the way that Ave propose, cannot but be useful botb 
to the geologist and the palaeontologist. The conditions of deposit 
will be elucidated by the proportions of fine and coarse materials in 
the beds ; especially if these be traced along a considerable tract by 
the examination of many samples of the deposit, through its varia- 
tions from clay to sand (or vice versa), or in its changes from an 
argillaceous or arenaceous to a calcareous condition. Such variations 
are not always recognized with sufficient exactness by the eye or by 
the pocket-glass, and require mechanical, if not chemical, analysis; 
recourse being had to the aid of acids in determining the relative pro- 
portions of lime and other constituents. Except by careful separa- 
tion in water, and patient sorting and picking, the minute shells and 
other fossils cannot be obtained in anything like a fair average ; and 
year by year the Eoraminifera, Entomostraca, Bryozoa, and the small 
* See Report of the Geological Society's Proceedings, Dec. 4tli, 1861. 
