5 io NOTES OF A BOTANIST CHAP. 



deep ravines, furrowed in soft alluvial sandstone 

 rock, wherein blocks and pebbles of quartz are inter- 

 spersed, or interposed in distinct layers. Towards 

 their source they are obstructed by large masses of 

 quartz and other rocks ; but as we descend the 

 stones grow fewer, smaller, and more rounded, until 

 towards the mouth of the Bombonasa, and thence 

 throughout the Pastasa, not a single stone of the 

 smallest size is to be found. The beaches of the 

 Pastasa consist almost entirely of powdered pumice 

 brought down from the volcano Sangay by the river 

 Palora. When I ascended the Bombonasa in the 

 company of two Spaniards who had had some 

 experience in mining, we washed for gold in the 

 mouth of most of the rivulets that had a gravelly 

 bottom, as also on some beaches of the river itself, 

 and never failed to extract a few fragments of that 

 metal. All these streams are liable to sudden and 

 violent floods. I once saw the Bombonasa at Puca- 

 yacu, where it is not more than 40 yards wide, rise 

 1 8 feet in six hours. Every such flood brings down 

 large masses of loose cliff, and when it subsides 

 (which it generally does in a few hours) the Indians 

 find a considerable quantity of gold deposited in the 

 bed of the stream. 



The gold of Canelos consists almost solely of 

 small particles (called "chispas," sparks), but as 

 the Indians never dig down to the base of the wet 

 gravel, through which the larger fragments of gold 

 necessarily percolate by their weight, it is not to be 

 wondered at that they rarely encounter any such. 

 I 'wo attempts have been made, by parties of 

 Frenchmen, to work the gold-washings of Canelos 



<j o 



.systematically. One of them failed in consequence 



