788 REPORTS ON THE STATE OF SCIENCE.—1913. 
APPENDIX. 
The Formation of *‘ Rostro-carinate’ Flints. 
By Professor W. J. Souras, F.R.S. 
[Ordered by the General Committee to be printed in extenso.} 
THE so-called ‘ rostro-carinate ’ flints discovered by Mr. Reid Moir at 
the base of the Red Crag and described by him? and Sir E. Ray 
Lankester ? are known to have passed through an eventful history since 
they were first liberated from the parent chalk. They were exposed 
to the influence of the weather, possibly to torrent action, almost cer- 
tainly to the impact of sea waves and as well, perhaps, to the pounding 
of coast ice on a beach. It would therefore seem reasonable to inquire 
whether they may not owe their peculiar forms to one or other of these 
natural agents. 
If we examine the flints of a shingle beach such as that which 
fringes the foot of the cliffs in Alum Bay, Isle of Wight, we shall find 
many which present a rude resemblance to ‘ rostro-carinates,’ but differ- 
ing too much in detail to be of great value as evidence. Thisis only what 
we might expect, since the momentum of a wave falling on loose shingle 
is dissipated for the greater part in producing a general movement of 
the material. How difficult it is to break a stone lying on loose pebbles 
is well known to every geologist who has made the experiment with a 
hammer. ‘The case is altered, however, when we pass, as at Selsey 
Bill, to thinly scattered flints lying on a sheet of firm clay. Here the 
blow of one stone driven upon another by the force of an advancing 
wave is capable of producing fractures on a larger scale. It was a 
consideration of this case that led me to visit Selsey, and I now propose 
to give a short account of the facts which fell under my observation at 
that place; but before doing so I should like to express my thanks to 
Mr. Heron-Allen, who guided me over the ground, and not only afforded 
me full access to his remarkable collection of flints from the foreshore 
of Selsey Bill, but gave me permission to help myself to any of the 
specimens which might prove of interest in this question. Mr. Heron- 
Allen has discovered many rostro-carinate forms among the Selsey flints, 
and one of them has been described by Sir E. Ray Lankester.*® 
The flints in question are exposed at Selsey Bill just above the mean 
level of the tide: they occur in scattered patches rather thinly strewn 
1 J. Reid Moir, ‘The Flint Implements of Sub-Crag Man,’ Proc. Prehistoric 
Soc. of East Anglia, 1911, vol. 1, p. 17. 
2 KE. Ray Lankester, ‘On the Discovery of a Novel Type of Flint Imple- 
ments,’ Phil, Trans. Roy. Soc., B, vol. 202, p. 283. 
5 Toc. cit. p. 332. 
