AND PORTO SANTO. 71 



Grande, and Canarios. That the plateau of the Poul was also 

 another point of eruption, I have no doubt, for the same reasons ; 

 but I have already submitted why there has, probably, never been 

 anything like a crater there. Some have considered the bay 

 of Funchal to be the segment of a large crater% but the rocks 

 of the bay do not afford more evidence of calcination than those of 

 the interior ; they are not at all vitreous, or approaching the 

 nature of obsidian, and instead of rising in lofty masses above the 

 level of the water, as if they had formed the walls of a crater, 

 they occur in basaltic strata of inconsiderable depth, alternating 

 with tufa, and with the most evident indications of having flowed 

 from the heights in the centre and interior of the island, which 

 are from 3500 to 6000 feet higher than this pretended crater. 

 ^Mien we recollect how fragile, how easily decomposed and dis- 

 persed, all the parts of a crater (constantly attacked by gases 

 and vapours) are, compared with the streams which issue from 

 it ; that nearly one quarter of the cone of Vesuvius fell in a 

 single eruption, and that during a repose of less than a century 

 and a half, it became covered with trees and plants — we cannot 

 wonder that all traces of the grand crater of Madeira should have 

 been effaced in the many ages which have elapsed since its 

 creation : the very convidsions which have so evidently rent the 

 Courals may have undermined its tottering remains. The basaltic 

 rocks of Madeira are probably of the same age as those of 

 Teneriffe, and, consequently, considerably older than the lavas 

 produced by existing causes in the latter island ; causes which 

 from local circumstances have not extended to Madeira. ' 



"f M. Guillin, in the Appendix of Bory St. Vincent's Voyage. See note to p. 25, 

 supra. 



' Shocks of earthquakes were felt in Madeira in 1813-14, from the N.W. ; and 

 January 11th, 1816. The latter is said to have lasted from fifteen to twenty minutes, 

 and to have cracked the beams of the houses, throwing; the inhabitants against the 

 walls ; it was felt at Lisbon and the Azores. 



