ARGENTINA 119 



which, meaning literally a thicket, is applied generally to all 

 the tract of forest land south of the Pilcomayo River lying 

 between the Andean foothills and the Parana. Its area is 

 close on 9000 square miles (23,000,000 hectares, to be exact), 

 of which a bare tenth has passed into private hands, and of this, 

 again, but a fractional part- exploited. Its formation is dis- 

 tinct from that found in any other forest of tropic South 

 America. A few inches of surface alluvial overlie a stiff boulder 

 clay, from 10 to 20 ft. thick, which in its turn rests upon a 

 substratum of pure sand. All well water must be obtained 

 from this sand, the depth at which it occurs varying in inverse 

 proportion to the distance of the bore from the banks of the 

 great parent river. 



" The timber in the Chaco is not continuous. It occurs in 

 long, narrow strips, which take a north and south direction, 

 and are interspersed with open ground in the proportion of, 

 perhaps, 40 per cent forest to 60 per cent of prairie. These 

 glades are, as a rule, covered with a rough pampa grass, but 

 where the clay lies directly on the surface there is only swamp, 

 worthless cactus, and thorny undergrowth. The whole for- 

 mation irresistibly suggests a previous inundation, in which 

 the parts now occupied by the forest have stood out above 

 the subsiding waters. So strong is the resemblance that the 

 belts of timber are known locally as ' isletas,' or islands. 



" The value of these islands lies in the fact that their woods 

 are composed for the greater part of ' quebracho,' a red hard- 

 wood, which also contains a valuable tanning extract. On 

 this account it resists indefinitely the action of water or dry 

 rot, and is much used for fence posts and general construction 

 work. It makes the finest railway sleeper in the world, 

 weighing nearly as much as lignum vitae, with a specific 

 gravity of 1.27, compared to 1.33 of the latter. It thus adds 

 greatly to the solidity of a road-bed, especially during the 

 trials of construction. 



" A league of good Chaco ground will yield 10,000 tons of 

 quebracho logs. Thus its value depends almost entirely on 

 the cost of timber transport to the nearest station. The limit 

 of profitable cartage does not extend beyond 20 miles from the 

 railway, beyond which the country is practically unknown. 



