465 



composed of several canals very close to each 

 other, and that a bifurcation is formed, when a 

 small portion of ground near the bank is lower 

 than the bottom of a lateral furrow *. 



According to the circumstances which we have 

 just related, the bifurcations of rivers take place 

 either in the same basin, or on the ridge of a 

 partition between two basins. In the first case, 

 they are either branches -f-, that re-enter the 

 thalweg from which they were separated at a 

 greater or less distance, or branches % which join 

 the lower tributary streams When the bifur- 



* See the memoir of Hydrography, which I published in 

 1810 in the Journal de VEcole Poly technique, vol. iv, p.65 — 68. 



f Near the principal, recipient, the connection between the 

 alternate slopes of different orders is generally such, that the 

 branches seldom flow from it. The great island, however, on 

 which the village of Morales stands, is three or four leagues 

 broad between the principal recipient of the Rio Magdalena 

 and the Brazo de Ocana. 



X See my maps of the Rio Apure and the Rio Magdalena. 

 The Guaricoto issues from the Apure to join the Portugueza, 

 which is a tributary stream of the Apure. Thus the Cano de 

 Lobo separates itself from the Magdalena to fall into the 

 Cauca. (See above, on an analogous interbranching of the 

 Amazon and the Jupura, p. 359.) As our maps in general 

 do not indicate the direction of the course of the waters, the 

 land lying between different branches of rivers, of which the 

 uppermost take water from the principal recipient while the 

 lowermost give water to it, is often taken, on a simple in- 

 spection of the figure, for a delta of tributary streams. 



§ There are, 1st, Oceanic deltas, as at the mouths of the 



VOL. V. 2 H 



