82 MR SMITH ON THE CHANGES 



the favourite scene of boyish amusement. I can per- 

 ceive that the sea has not beat against it so long in vain - r 

 one part of it was hewn into a particular shape, the pro- 

 jecting corners of which are worn away, but in the body of 

 the rock itself, no trace of loss can be perceived. A flight 

 of steps near this have lost none of their perpendicularity, 

 and some millstones which have formed part of a break- wa- 

 ter for at least a century, have apparently lost none of their 

 original thickness. The rate of waste in this locality is 

 therefore extremely slow ; but as, both from the nature of 

 the rock, and the moderate force of the sea in a narrow 

 sound, it must be very regular, were the spots where such 

 observations are made carefully marked, future observa- 

 tions might afford something like a measure of the time re- 

 quisite for producing such effects. 



I formerly expressed an opinion that some change had 

 taken place in the testaceous fauna of Britain since the last 

 alterations of the sea-level, and that, although a large pro- 

 portion of the shells were identical with those of the pre- 

 sent epoch, some of them had become extinct. I am con- 

 firmed in this opinion, both from the observations I have 

 since made, and from those of others. Professor Phillips 

 states, that " among a dozen or twenty shells in the gravel 

 of Holderness, one extinct species is met with.'"* On the 

 coast of Wexford, Mr Griffiths found shells of existing, 

 and also of extinct species, some of which appeared to cor- 

 respond with those of the crag.-f* Mr Woodward marks 

 theBuccinumgranulatum,an extinct crag-shell, amongst the 

 fossils of the brick-earth in Norfolk which belongs to this 

 formation ;j and Mr Murchison, amongst sixteen species of 



* Treatise on Geology, vol. i. p. 299. 

 t Proceedings of Brit. Assoc. 1835. 

 X Woodward's Geology of Norfolk, p. 36. 



