151 



head. Saccharum and Imperata were both present, and with 

 them occasionally another unidentified species which closely 

 resembled in vegetative habit the American Andropogon fur- 

 catus. One outlying promontory of the island was occupied 

 chiefly by this, with an effect much like that of the bunch-grass 

 association of the prairie states. Mixed with the dense cogon 

 were scattered shrubs of various species. Commonest among 

 them by all odds was Acacia Farnesiana, sometimes well loaded 

 with pods. Among the other less common species were a Cissus, 

 Tahernaemontana sp.,Cordia myxa,,Desmodmm tenellum, an Indigo- 

 fera, and a gourd with warty, orange, melon-like fruits five inches 

 in diameter. The size and age of all these was such that they 

 seemed to be recent introductions since the eruption. 



As we gradually ascended the sides of the mountain and pene- 

 trated farther inland, the vegetation became more and more 

 sparse. This decrease seemed to be correlated with the prox- 

 imity of the crater, rather than with the altitude. The cogon 

 began to disappear first from the crests of the ridges, then from 

 the bottoms, until half way to the crater it occupied only the 

 smaller ravines, which it colonized in long strips. The last 

 ascent of the crater was considerably steeper, and here the cogon 

 disappeared entirely, exposing hundreds of acres of perfectly 

 bare yellow-brown ash. 



With the torrential tropical rains, and with a loose soil of 

 ash entirely unprotected by vegetation, the rapidity of erosion 

 is very great. It has resulted in the working out within three 

 years of a most elaborate system. Every feature of erosive 

 activity and result taught by physiography may be observed 

 within a very little distance, from stream piracy to meandering, 

 and viewed from the summit of the mountain the surface of the 

 island looks like a physiographic model. 



Because of the great relief, the erosion is at first chiefly in 

 depth, and results in a narrow canyon with vertical walls and 

 flat bottom. One may find such a canyon a foot wide and a foot 

 deep, and by stepping into it and following it to the lake, ob- 

 serve its whole history. It becomes rapidly deeper, while pre- 

 serving its vertical sides, and an obstruction or hard stratum in 



