The Causes and Phenomena, of Earthqitafces. 69 



mechanical expansion laterally and vertically, thus causing many 

 of the phenomena observed in strata, which hasty conclusions 

 refer to the direct agency of igneous force. 



Incidentally, to point out how even the solar heat affects ex- 

 pansion of some of the sandstone in this county of Cumberland, 

 I would refer observers to the coping of bridges, such as that of 

 Parramatta, which is formed of a different rock to the mass of 

 the bridge. The alternate expansion and contraction of the 

 exposed stone causes the cement to be disturbed and gaps to be 

 produced ; an effect also observed in houses where careless 

 builders cement with untempered mortar. 



It may be further remarked, that the removal of sedimentary 

 matter from one region to another by the ordinary agencies of 

 water, may, by pressure produced in the region to which it is 

 carried, also cause change of level. So that all must not be 

 assigned to earthquake shocks, though the coasts of Chili, and 

 more recently the shores of Cook's- Strait, in New Zealand, have 

 been elevated within the last half century by earthquakes. 



For the sake of convenience, and to meet a reference made to 

 me by some gentlemen in Sydney, I here introduce a remark or 

 two respecting the Chili earthquake of 19th November, 1822. 

 It is stated by Mrs. Graham, who was on the spot, that the coast 

 was elevated over more than 100,000 square miles, and from 2 to 

 4 feet. Sir C. Lyell has collected the testimonies in confirmation, 

 and says that from the calculations he has made from the state- 

 ments of Cruickshanks, Meyen, Freyer, and Darwin, the mass 

 raised must have exceeded in weight 100,000 times that of a 

 mass equal to that of the great pyramid of Egypt, if solid, which 

 would then weigh 6,000,000 tons, and assuming the probable 

 thickness of strata below at only two miles, then the weight 

 would exceed that of 363,000,000 pyramids. 



Sir J. Herschel (Familiar Lectures, p. 5), says that Aconcagua, 

 one of the Andes, overlooking Valparaiso, nearly 24,000 feet in 

 height, was raised, and that 10,000 square miles of country were 

 upheaved with it. If, however, as is possible, the raised area was 

 at the base of the Andes, then the mountain might not have 

 partaken of the rise ; and it is only right to add that some of the 

 statements made by other observers were called in question by 

 Admiral Belcher, Lieutenant Bowers, and Mr. Cuming, [Their 

 communications may be found in the Proceedings of the Geological 

 Society, vol. 2, p. 213-14.] The elevation along Cook's Strait is 

 well ascertained. 



I must now briefly refer to the labours of a foreign seismolo- 

 gist, whose work is not considered altogether favourably by Mr. 

 Mallet. I allude to the Theorie des Volcans by Count de Bylandt 

 Palstercamp, the Avant propos of which was privately sent to me 

 in 1833, and reviewed by me in the Magazine of Natural History 



