218 J. S. GARDNER——DESCRIPTION AND 
Prof. Prestwich took for a “ slight throw-in of an overlying stratum ” 
of the Barton beds. The shingle is imbedded, as usual, in white sand, 
and underlain by yellow and grey sand in layers, and then by darker 
clayey sand. ‘The cliffs are here 30 feet high with an easterly dip 
of 7°, and are more than halt composed of gravel ; 260 yards further 
the dip decreases to 5°, and we have in descending order ash-coloured 
sand and clay, a narrow seam of pink clay, white sand shading to 
fawn, a thin line of dark clay, lemon-coloured sand, and 23 feet white 
sand with laminated pale drab clays. A little westward a layer of iron 
sandstone appears; and 100 yards further the dip decreases again to 
3° or 4°. At this point we find irony and fawn-coloured sands irregu- 
larly bedded under the gravel, then sandy laminated clay with two 
layers of orange-coloured clay, succeeded by three layers of black 
clay between lignitic sand. Under the flagstaff is an important 
shingle deposit comprising two nearly herizontal and parallel layers 
at its base, and several masses bedded obliquely at an angle of some 
25° above. The whole of the shingle-beds appear to have been mis- 
taken for diluvium by Lyell, but were recognized by Prestwich and 
distinguished from the surface-gravel. They consist, he says *, 
‘“‘uniformly and solely of perfectly rounded smaller or larger flint 
pebbles, mixed with more or less sand, and always, when the latter 
predominates, showing distinct though rough stratification.” <A 
section by Prestwich appears to have been taken from this spot, 
where the flints are very large and round. For 400 yards there is no 
change of importance; but the base-beds show clearly defined stratula, 
which prove, like the slope of the old shingle beaches, that they were 
thrown down by water advancing from the eastward. At this point 
occur more dark lenticular clay patches of the Bournemouth beds ; 
and through the increased height of these more of the overlying Bos- 
combe Sands seem to have escaped denudation. The line of sepa- 
ration between these latter and the beds below may be distinctly 
traced,as a thin but more or less persistent clay seam checks the down- 
ward percolation of water, and throws it out in numerous tiny 
springs, the wet uniformly darkening the beds below even where they 
are composed of white sand. The clay patches continue without change 
for 150 yards. ‘The cliffs are then 65 feet high, 40 feet belonging to 
the lower series and 20 to the Boscombe Sands, with little or no 
gravel capping. ‘The upper beds exhibit stratula at reversed angles, 
showing cross currents, or that the prevailing set of the tides was 
often changed. The lower beds change frequently from dark clays 
to buff or white sands, sometimes within 10 yards, and contain great 
lenticular patches scooped out of them and filledin with white sand, 
marking probably former channels parallel with the shore, such as 
we see to-day on the same spot. ‘The damp surface of the cliffs, to 
which blown sand clings, obscures, however, most of these changes, 
and they must be bared with a spade or pick to be visible. They 
are most distinct after heavy rain. About 400 yards beyond a little 
chine in which the coastguard boats are sheltered, the junction line 
is temporarily lost, and the whole cliff is composed of yellow sand, 
* Prestwich, Quart. Journ. Geol. Soc. vol. v. p. 46. 
