94 Capt. Bayfield's Notes on 



marks of the sea having remained for a considerable time at different levels ; to which parallel 

 beaches of limestone shingle correspond. 



I imagined, at first, that the peculiar shapes of these natural columns might be the effect of at- 

 mospherical agents, and the unequal hardness and consequent power to resist that effect, in the dif- 

 ferent alternating strata of limestone. Observation however soon convinced me, that these agents 

 are incapable of producing such effects. They may and do wear away the cliffs rapidly, aided by 

 the expansive power of freezing water, in a climate whose winter temperature is so low ; and if the 

 cliff be composed of strata of a nature to be unequally acted upon, it may be undermined, or several 

 projecting ledges may be left, and these may be divided by natural fissures, so as to cause the 

 face of the cliff to assume a variety of shapes ; but a talus is soon formed which protects it from 

 further destruction from this cause. 



The action of the atmosphere alone, therefore, cannot form groups of isolated natural columns 

 or perforated rocks, and carry away the debris or arrange it in parallel beaches of waterworn 

 fragments, whose levels correspond with those at which the columns remain, or to the parts 

 of those columns which appear to have been worn slender by the long continued action of the 

 waves. But if we attend to what is going on at present on these islands, we shall have little dif- 

 ficulty in deciphering the memorials of the past. We see columns of limestone, evidently the 

 ruins of former cliffs, assuming the various shapes of flower-pots, towers, arches, &c., and standing 

 on the gently shelving limestone, laid dry only at low water, and at a short distance from the per- 

 manently dry shore. They are worn away by the waves acting upon a space which depends upon 

 the rise of the tide, until they become very thin at the mean level of the sea. It is thus that they 

 so frequently assume the shape which has led to their being termed flower-pots. The limestone 

 gives way to this incessant washing, in angular fragments, which, after undergoing attrition in the 

 surf for some time, are finally deposited in beaches of shingle, upon the shelving limestone, at an ele- 

 vation corresponding to the highest rise of the tide. Such is the process at present, and the columns, 

 with beaches of corresponding elevation, were observed to be forming in every favourable situation. 



Now the columns which occupy levels far above the reach of the sea at present, are not only ex- 

 actly similar in appearance and shape to those which are forming, but are accompanied by beaches 

 of limestone shingle, more or less waterworn, and of corresponding elevation to the worn stems or 

 shafts of the flower-pot columns. 



These appearances, I think, can only be explained by allowing, as before stated, either that the 

 land has been raised, or that the level of the ocean has fallen. In either case the changes of level 

 have been only a few feet at a time, with long intervals between, as is indicated by the wearings 

 of the columns, which must have required a long period of years, and by the succession of the 

 beaches one above another*. 



* There is one more indication which was observed by Dr. Kelly, R.N., in the harbour of 

 Quarry island. He there found the limestone perforated by Lithophagi at a height not reached 

 by the sea at present, excepting perhaps in very high spring tides. The harbour is so well 

 sheltered that there is never any surf to wash this perforated ledge of limestone when the water 

 does not otherwise rise to it. Considering all the circumstances, it is possible that the sea may attain 

 the height of these perforations, and remain at it for an hour or two at a time, during two or three 

 tides in a month ; but it is probable that in the summer, when there are seldom gales to cause 

 extraordinary high tides, the ledge may not be reached by the water for two or three months in 

 succession. 



Lithophagi could not possibly live in such a situation, perfectly dry and heated by the sun for 

 weeks together. We frequently found masses of limestone on the beaches perforated by Lithophagi, 

 the shells of which remained in the cavities, but they appeared to have been washed up by the 

 surf, and we have every reason to believe that these animals live, either constantly submerged, 

 or in situations which are dry only for a short time during each tide. 



