360 Dr James Macaulay on the Physical Geography^ 



island would prevent its being seriously entertained. The na- 

 ture and the amount of the non-volcanic formations, the posi- 

 tion they occupy amidst the pyrogenous products, and the 

 manner in which the various rocks are situated, sufficiently de- 

 monstrate that no former track of land has been submerged, 

 but that the island has, by the force of submarine volcanic ac- 

 tion, been raised to its present state ; and that the older strata, 

 fragments of which now appear even at a great elevation, were 

 originally formed at the bottom of the sea, and remained there 

 till disturbed and heaved up by the igneous agency. That the 

 present Archipelago of Madeira is but the fragment of a greater 

 region, Sr. M. d' Albuquerque further argues, from the absence 

 of any focus of divergent currents, and the general inclination 

 of all the beds of lava, which he says is in the direction of 

 south-west. This inclination is certainly far from obvious ; for, 

 as already stated, the beds lie in various directions, and seem 

 to diverge not from one but from many foci of volcanic energy. 

 There is certainly no where to be seen anything like a well- 

 marked crater, such as those of Auvergne and other districts 

 of extinct volcanic action. Some have considered the Corral 

 to be the crater of the island. I believe it to have been only 

 one of the several centres of eruption indicated by the direc- 

 tions of the basaltic beds. Another, for instance, and equally 

 well-marked, seems to have had its site in the present bay of 

 Funchal. The outline of this crater may be traced partly by 

 the line of basaltic rock at the Pontinha,, which, running out 

 into the sea, forms the pier there, and part of the continuation 

 of which is seen in the basaltic island on which the Ilheo fort 

 in the bay is built. Other centres of eruption are obvious in 

 different parts of the island. The only difficulty in the way of 

 supposing these to have been the volcanic craters of the island 

 is their immense size. But every thing around bears token of 

 the gigantic scale on which the igneous agency must here have 

 been in operation. The vast volume of the basaltic formations, 

 the thickness of the strata of conglomerate and volcanic sand, 

 and the enormous quantities oi' scoriae and other ejected mat- 

 ters, prevent any surprise as to this matter. Even in the com- 

 paratively tranquil state of things since the commencement of 



