CATARACTS, AND INUNDATIONS. 121 



others of a yellow substance ; and again others of a gray lava, 

 mixed \vith a great quantity of v, hite glass: But the most curious 

 consisted of an heterogeneous mixture of various substances, ce- 

 mented indiscriminately together by some operation, subsequent to 

 their original formation, and so strongly that the rock was broken 

 with diiiiculty by our hammers. It consisted of pieces of black glass 

 (a lava in all probability much vitrified), and large pieces of a 

 cloio, gray lava, the cavities and pores of which were filled with 

 zeolites finely radiated. Some pieces of black lava, in parts com- 

 pact, and in other parts so porous as to approach nearly to a 

 pumice stone, were mixed with the rest of the mass. A mixture 

 of the same substance, (the lavas, the glass and the zeolites), 

 pounded in small grains tilled the spaces between the larger pieces, 

 and connected the whole into a solid rock. The heat (if heat it 

 was) which had cemented these materials, had not been strong 

 enough to reduce anyone to a state of fusion; for the angles of 

 the fragments were as sharply defined as if newly separated from 

 their respective original beds. 



The rocks from whence these different masses have been de- 

 tached, lay heaped together in so disjointed and irregular a manner 

 that some violent convulsion has evidently taken place amon- them 

 since their first formation ; but similar appearances of disorder are 

 to be seen in every range of hills in the country. Regular strata are 

 no where to be met with. It appears as if all this part of the 

 island, at different periods, had been thrown up from its foun- 

 dations. 



The valley is in this place fertile, and nearly half a mile in 

 "breadth. It becomes more narrow towards the north ; and it is 

 there rendered barren by heaps of crumbled lava, or other 

 rubbish, brought down from the hills by waters. These have the 

 appearance of artificial mounds, and a great number of springs are 

 continually boiling through them. Below the surface, a general 

 decomposition seems taking place ; for almost whenever the ground 

 is turned up, a strong heat is felt, and the loose earth and stones 

 are changing gradually into a cluy or bole of various colours and 

 beautifully veined, resembling a variegated jasper. The heat may 

 possibly proceed from a fermentation of the materials composing 

 these mounds ; but more probably (I should conjecture) from th^ 

 springs ami steam forced up 1hrotili them. The springs must have 



