no 



THE LOWER AMAZONS. 



fore their influence is felt upon the other. Along the 

 line of table-lands and mountains that feed the southern 

 tributaries, the rainy season commences about September, 

 gradually swelling those streams, which slowly roll their 

 floods toward the centi'e of the valley, reaching the Ama- 

 zons with their highest waters about the last of February 

 or the first of March. Simultaneous with these contribu- 

 tions from the south, the streams along the slope of the 

 Andes are adding their swollen waters to the great river. 

 At this time the Rio Negro, as we have remarked in 

 speaking of that river, is lowest, and its mouth is dammed 

 np, and its current even turned back by the mass of water 

 from the southern tributaries. By February the rainy 

 season is flooding the highlands of Guiana and the Cordil- 

 leras of Colombia, v>'hen the Rio Negro and the other 

 northern aflluents carry down their gathered floods, at- 

 taining their greatest rise in June, by Avhich time the 

 southern rivers have fallen. Thus but one set of tributa- 

 ries is acting at once, to lift the level of the Amazons. 

 Should both simultaneously roll down their accumulated 

 spring floods, the forest in the centre of the valley would 

 be almost submerged. As it is, the Amazons rises be- 

 tween forty and fifty feet above its lowest level, and the 

 valley for several miles either side of the river is laid un- 

 der water. Some writers, from the manner in which they 

 have spoken of the inundation of the valley, leave the im- 

 pression that its whole extent is flooded as completely as 

 the Llano s during the spring-tides of the Orinoco. But 

 the portion of the plain overflowed is comparatively small. 

 At the time of the highest rise, the forests are flooded 

 back probably not more than an average of fifteen miles 

 from the banks of the river, while the greatest width of 

 the valley is over seven hundred miles. . This is true of 

 the Amazons only between the mouth of the Tapajos and 

 Fpper Peru, a distance of seventeen hundred miles. Be- 



