304 



CHARLES DARWIN 



of Tierra del Fuego than that of northern Chiloe; for every 

 patch of level ground is covered by two species of plants 

 (Astelia pumila and Donatia magellanica), which by their 

 joint decay compose a thick bed of elastic peat. 



In Tierra del Fuego, above the region of woodland, the 

 former of these eminently sociable plants is the chief agent 

 in the production of peat. Fresh leaves are always succeed- 

 ing one to the other round the central tap-root; the lower 

 ones soon decay, and in tracing a root downwards in the peat, 

 the leaves, yet holding their place, can be observed' passing 

 through every stage of decomposition, till the whole becomes 

 blended in one confused mass. The Astelia is assisted by a 

 few other plants, — here and there a small creeping Myrtus 

 (M. nummularia), with a woody stem like our cranberry and 

 with a sweet berry, — an Empetrum (E. rubrum), like our 

 heath, — a rush (Juncus grandiflorus), are nearly the only 

 ones that grow on the swampy surface. These plants, though 

 possessing a very close general resemblance to the English 

 species of the same genera, are different. In the more level 

 parts of the country, the surface of the peat is broken up into 

 little pools of water, which stand at different heights, and 

 appear as if artificially excavated. Small streams of water, 

 flowing underground, complete the disorganization of the 

 vegetable matter, and consolidate the whole. 



The climate of the southern part of America appears partic- 

 ularly favourable to the production of peat. In the Falkland 

 Islands almost every kind of plant, even the coarse grass 

 which covers the whole surface of the land, becomes con- 

 verted into this substance: scarcely any situation checks its 

 growth ; some of the beds are as much as twelve feet thick, 

 and the lower part becomes so solid when dry, that it will 

 hardly burn. Although every plant lends its aid, yet in most 

 parts the Astelia is the most efficient. It is rather a singular 

 circumstance, as being so very different from what occurs 

 in Europe, that I nowhere saw moss forming by its decay 

 any portion of the peat in South America. With respect to 

 the northern limit, at which the climate allows of that pecul- 

 iar kind of slow decomposition which is necessary for its 

 production, I believe that in Chiloe (lat. 41 ° to 42 0 ), although 

 there is much swampy ground, no well-characterized peat 



