392 Mr. Bennett 0/; the Geology of Madeira. 



with the cedar and other trees pecuUar to southern latitudes, and with- 

 a profuse variety of shrubs and plants, among which the Erica Ar- 

 borea is the most beautiful, and in the greatest quantity. 



The Island of Madeira (though I believe it never has been sur- 

 veyed) is said to be about 50 miles in length, and in its broadest part 

 about 20, but the average breadth does not exceed 15 miles. 



It consists of a succession of lofty hills rising rapidly from the sea, 

 particularly on the eastern and northern extremities. The summits of 

 many of these ranges present the appearance of what has been called 

 a Table Land, yet occasionally the forms are conical, and surmounted 

 by a peak, which in some instances I found to be of columnar 

 basalt. Deep ravines or vallies descend from the hills or scrras to 

 the sea, and in the hollow of most of them flows a small river, which 

 in general is rapid and shallow. The soil of the island is clay on the 

 surface, and large masses of it as hard as brick are found underneath. 

 Though there are not at present any existing volcanoes in the island, 

 yet the remains of two craters are to be seen, one on the eastern, the 

 other on the western side, the largest being about a Portuguese 

 league, or four English miles in circumference. Every thing around 

 wears marks of having suffered the action of fire, yet I was unable 

 to discover any deposit of sulphur, and was told that none had 

 hitherto been found in the island. 



The varieties of strata, which I shall term generally lava, are not 

 numerous. I myself saw but four, and I was informed there were 

 no more to be met with. Three of them were invariably alternating 

 in the same order. The first or lowest lava is of a compact species, 

 containing few, if any, extraneous substances, is of a blue colour, 

 and of a remarkably fine grain. Upon that, the second, which is a 

 red earthy friable lava, rests ; sometimes separated by beds of clay 

 mixed with pumice, and layers of black ash and pumice. This red 



