326 



CHARLES DARWIN 



that the walls running S.W. and N.E. which presented their 

 ends to the point whence the undulations came, would be 

 much less likely to fall than those walls which, running N.W. 

 and S.E., must in their whole lengths have been at the same 

 instant thrown out of the perpendicular ; for the undulations, 

 coming from the S.W., must have extended in N.W. and 

 S.E. waves, as they passed under the foundations. This may 

 be illustrated by placing books edgeways on a carpet, and 

 then, after the manner suggested by Michell, imitating the 

 undulations of an earthquake : it will be found that they fall 

 with more or less readiness, according as their direction more 

 or less nearly coincides with the line of the waves. The fis- 

 sures in the ground generally, though not uniformly, extended 

 in a S.E. and N.W. direction, and therefore corresponded 

 to the lines of undulation or of principal flexure. Bearing in 

 mind all these circumstances, which so clearly point to the 

 S.W. as the chief focus of disturbance, it is a very interesting 

 fact that the island of S. Maria, situated in that quarter, was, 

 during the general uplifting of the land, raised to nearly 

 three times the height of any other part of the coast. 



The different resistance offered by the walls, according to 

 their direction, was well exemplified in the case of the Cathe- 

 dral. The side which fronted the N.E. presented a grand 

 pile of ruins, in the midst of which door-cases and masses 

 of timber stood up, as if floating in a stream. Some of the 

 angular blocks of brickwork were of great dimensions; and 

 they were rolled to a distance on the level plaza, like frag- 

 ments of rock at the base of some high mountain. The side 

 walls (running S.W. and N.E.), though exceedingly frac- 

 tured, yet remained standing; but the vast buttresses (at 

 right angles to them, and therefore parallel to the walls that 

 fell) were in many cases cut clean off, as if by a chisel, and 

 hurled to the ground. Some square ornaments on the cop- 

 ing of these same walls, were moved by the earthquake into 

 a diagonal position. A similar circumstance was observed 

 after an earthquake at Valparaiso, Calabria, and other places, 

 including some of the ancient Greek temples. 1 This twist- 

 ing displacement, at first appears to indicate a vorticose 



1 M. Arago in L'Institut, 1839, p. 337. See also Miers's Chile, vol. i. p 

 392; also Lyell's Principles of Geology, chap, xv., book ii. 



