PLATEAU OF CAXAMARCA. 281 



between Santiago and San Borja, in a mountain ravine where 

 at some points the overhanging rocks and the canopy of 

 foliage forbid more than a very feeble light to penetrate, and 

 where all the drift wood, consisting of a countless number 

 of trunks of trees, is broken and dashed in pieces, the 

 breadth of the stream is under 160 English feet. The rocks 

 by which all these Pongos or Narrows are formed undergo 

 many changes in the course of centuries. Thus a part of 

 the rocks forming the Pongo de E/entema, spoken of above, 

 had been broken up by a high Hood a year before my jour- 

 ney ; and there has even been preserved among the inhabi- 

 tants, by tradition, a lively recollection of the precipitous 

 fall of the then towering masses of rock along the whole of 

 the Pongo, an event which took place in the early part of 

 the eighteenth century. This fall, and the consequent 

 blocking up of the channel, arrested the flow of the stream ; 

 and the inhabitants of the village of Puyaya, situated below 

 the Pongo de Kentema, saw with alarm the wide river-bed 

 entirely dry : but after a few hours the waters again forced 

 their way. Earthquake movements are not supposed to 

 have occasioned this remarkable occurrence. The powerful 

 stream appears to be as it were incessantly engaged in im- 

 proving its bed, and some idea of the force which it exerts 

 may be formed from the circumstance, that notwithstanding 

 its breadth it is sometimes so swollen as to rise more than 

 26 English feet in the course of twenty or thirty hours. 



"We remained for seventeen days in the hot valley of the 

 Upper Maranon or Amazons. In order to pass from thence 

 to the shores of the Pacific, the Andes have to be crossed at 



