Trans. N. V. Ac. Sci. 4 Oct. g, 



lantic seas ; whilst in the neighboring chalk cliffs there are several 

 deep caves. Prof. Day described one of these caves which can be de- 

 scended into at the landward end. (Mr.WHiTEHOUSE here exhibited to 

 the audience a view of this cave, which he said was " the very one that 

 first suggested to him, that the caves of Staffa, as well as these, were 

 artificial.") In continuation, Prof. DAY stated that Mr. WhitehOUSE 

 laid great stress on the necessity of very heavy waves to produce such 

 caves. He reminded him that water charged with gravel and sand was 

 the real agent of erosion, and that water so charged, even if only gently 

 moved, could in the course of time produce great destruction. More- 

 over, waves of very limited size have very great destructive powers, as 

 evidenced in the displacement of the granite blocks, that form the tur- 

 tleback built to protect Execution Lighthouse in the Sound. Nor is 

 there any proof, that the speaker knew of, that heavy ocean waves do 

 bore caves into cliffs in the direction of their impact. The very vi- 

 olence and evenness of their attack is opposed to such a result. If one 

 section of a cliff is weaker or more exposed than the rest, a bay will be 

 formed ; and a projecting headland between two such bays may be 

 eaten through from each side, not by the direct attack of the heavy 

 breakers, but rather by the incessant swirl of the waters, as they eddy 

 around in the bays at its base. In such case, first a cave, then a high 

 arch, and finally a chasm would be formed, but transversely to, not in 

 the line of attack of, the ocean waves. Such arches, and the isolated 

 pinnacles which are the final results, are common features on every rock- 

 bound coast. 



Moisture laden with sea-salts was a powerful though slow agent of 

 erosion, very effective, as the speaker had seen, alike on churches on 

 the south coast of England, built of perishable marlstone, and on 

 the granite cliffs of Cornwall. To assume, as the author did, that frost 

 had played no part in the formation of these caves, because there was at 

 the present day no frost to speak of in that locahty, and to argue that 

 the sea could not at its present level have its share in the work, is to 

 assume that there have been no changes of level in the coast of Scotland, 

 and no changes of climate, since the commencement of the formation 

 of these caves — a proposition that begs the whole question of the date 

 of their origin. 



Again, the author had totally ignored the action of water percolating 

 through rocks, as another assistant in the work of erosion. That water 

 did percolate through these rocks was evident from the mention made 

 of stalactites in these caves ; and, in some of the pictures shown, it cer- 

 tainly appeared as if the caves had been formed along lines of fissure. 

 (Mr. WHITEHOUSE stated positively, however, that there were no fis- 

 sures.) In" all limestone cliffs we may expect to find caves which had 



