The northern part of the Gran Chaco is partly wooded and swampy, and as the slope eastward is very gentle and the rivers much obstructed by sand bars, floating trees and vegetation, large areas are regularly flooded during rainy seasons.
The general elevation of the Chaco varies from 600 to 800 ft.
These Chaco rivers are obstructed by sand bars and snags, which could be removed only by an expenditure of money unwarranted by the present population and traffic. In the southern pampa.
The territories of the Gran Chaco, however, are covered with a characteristic tropical vegetation, in which the palm predominates, but intermingled south of the Bermejo with heavy growths of algarrobo, quebracho-colorado, urunday (Astronium fraxinifolium), lapacho (Tecoma curialis) and palosanto (Guayacum officinalis), all esteemed for hardness and fineness of grain.
In the " mesopotamia " region the flora is similar to that of the southern Chaco, but in the Misiones it approximates more to that of the neighbouring Brazilian highlands.
The " nandu " or American ostrich (Rhea americans), inhabiting the pampas and open plains of the Chaco, has in Patagonia a smaller counterpart (Rhea Darwinii), which is never seen north of the Rio Negro.
In the Chaco the tapir or anta (Tapir americanus) still finds a safe retreat, and the peccary (Dycotyles torquatus) ranges from Cordoba north to the Bolivian frontier.
Pelleschi's Eight Months on the Gran Chaco; R.
The vegetation is similar to that of Paraguay and the Chaco, and aquatic plants are specially numerous and luxuriant.
By Salta and the Chaco territory, E.
By the Chaco and Santa Fe, S.
Brazil; Caribian, around Caribbean Sea; Catamarenyan, Chaco; Changuinan, Panama; Charruan, Parana R.; Chibchan, Colombia .; Churbyan, Orinoco R.; Coconucan, Colombia; Cunan, Panama; Guaycuruan, Paraguay R.; Jivaroan, Ecuador; Kechuan, Peru; Laman, N.E.
Del Fuego; Paniquitan, Colombia; Panoan, Ucayali R., Peru; Payaguan, Chaco; Puquinan, Titicaca L.; Samucan, Bolivia; Tacanan, N.
The city faces upon a curve in the river bank forming what is called the Bay of Asuncion, and is built on a low sandy plain, rising to pretty hillsides overlooking the bay and the low, wooded country of the Chaco on the opposite shore.'
The Buenos Aires treaty of the 3rd of February 1876 fixed the frontier between Argentina and Paraguay, and assigned to Paraguay the portion of the Gran Chaco between Rio Verde and Bahia Negra; the appropriation of the portion between Rio Verde and the Pilcomayo was submitted to the arbitration of the president of the United States, who in 1878 assigned it to Paraguay.
From this centre Spanish adventurers pushed east to La Guayra, beyond the Parana, and west into the Gran Chaco; and before long vast numbers of the less warlike natives were reduced to serfdom.
Grubb, Among the Indians of the Paraguayan Chaco (London, 1904); E.
In the extreme south are the Bolivian Chaco and the llanos (open grassy plains) of Manzo, while above these in eastern Chuquisaca and southern Santa Cruz are extensive swamps and low-lying plains, subject to periodical inundations and of little value for agricultural and pastoral purposes.
Nothing definite is known of its tributaries in the Chaco, but in the sierra region it possesses a number of small tributaries, the largest of which are the Cachimayo, Mataca and Pilaya or Camblaya, the latter formed by the Cotagaita and San Juan.