AND PORTO SANTO. 67 



It is within a mere hillock, of an imperfect, conical form, on a plain 

 2406 feet above the sea, from which it is only three miles distant 

 on the south east, it is about ten miles distant from the east, and 

 thirty from the west end of the island, and has peaks or mountains 

 in its rear, rising from 2000 to 3600 feet above it. These moun- 

 tains being composed of ridges or streams of basalt, of the same 

 nature as that at the water side, alternating with tufa and scoriae, 

 and intersected by descending dikes, even at a height of 5000 

 feet, no one can conceive them to have been masses hfted up from 

 the sea, at the foot of which a crater afterwards opened, as in the 

 formation of Sabrina. The interior form of the Lagoa is certainly 

 in its favour, but there is no wall, or even fragment of a ^\ all, nor, 

 indeed, is there an atom of lava, pumice, or obsidian to be picked up 

 in its neighbourhood. There is not a single ridge or stream of 

 basalt to be traced from it, nor is there a single bed of scoria?, both 

 of which woidd have remained in evidence, however long the 

 crater may have ceased to vomit them ; the remoteness of which 

 period makes the absence of all traces of sulphur still more extra- 

 ordinary : in short, the mineralogist would quit it totally disap- 

 pointed. Its size, which every observation on record would re- 

 quire to be the more considerable, from its very Ioav position, is truly 

 diminutive, the greater axe of the eUipse (bearing E. 30°, S.) 

 being only about 240 feet, the lesser (bearing S. 38°, W.) only 

 190 feet, and the depth only fifty-four feet. There was a small 

 pool of rain water in it about a foot deep, and the whole surface 

 was covered with a deep bed of vegetable earth, which, from the 

 evidence of that in the neighbourhood, probably reposes on tufa ', 



' The length of Madeira, from Porta de Pargo to Porta St. Lorenzo, is9| P. leagues 

 (321 Cr. miles), according to the survey of Col. Paulo d' Almeida, being 6 G. miles 

 less than the distance between the same points in Johnston's Geo-hydrographic Survey 

 of Madeira, pubHshed by Faden in 1790 : the greatest breadth is from Porta da Cruz 



K2 



