299 



coast, and in the centre of the island, is not less than 1500 

 feet high. 



" The whole island appears to be one solid mass of trap. 

 There is no variety. The rock is of a bluish colour in the 

 recent fracture, and thickly interspersed with crystals of 

 olivine. The rolled fragments, when broken, sometimes 

 exhibit drusy cavities lined with zeolite. The mountain- 

 masses are disposed in thick strata, or beds, forming a con- 

 siderable angle with the horizon. Even the loose fragments, 

 where they have not been displaced by the operations of 

 agriculture, are often arranged with surprising regularity; 

 and we can trace in them an approximation to the prismatic 

 figure. Their upper and lower sides are flat, and the circum- 

 ference of from three to six, but generally fiv^e, faces. In 

 some parts of the island, we meet with tesselated patches, a 

 quarter of a mile in extent, consisting of a smooth sheet of 

 rock, cracked into these prismatic fragments, and so nicely 

 adjusted to each other, that room is barely left for a line of 

 verdure in the fissures to mark their division. 



" In the faces of the deep ravines through which most of 



the rivers have worked their channels, the rocks occasionally 



display the columnar form of basalt: exhibiting both the 



perpendicular and the horizontal section, as well as the angles 



of the columns. In other parts, where this regularity does not 



prevail, we may observe the prismatic masses lying over each 



other, but separated by the intervention of a layer of earth, 



the product, apparently, of their own decomposition. In the 



same manner they stretch out into the sea on every side of 



the island, giving a solid base to those coralline fabrications 



which are generally believed to compose the whole reef; though 



it is more probable, that they only form the superficial crust. 



" The soil of Mauritius is a tenacious earth of a ferruffi- 



o 



nous colour, mixed with a very small proportion of vegetable 

 mould. In the dry season, it becomes extremely hard, and 

 cracks into numerous fissures. In some parts of the island, 

 it is sufficiently plastic to admit of being manufactured into a 

 sort of bottles called Gargoulettes, which possess the 

 inestimable quality of preserving water, at a temperature 



