CiiAP. V. ROUND ISLAY. 71 



of carpenter, cooper, and blacksmith ; and to whom we were 

 indebted for mnch valuable assistance in procuring soil for 

 the Wardian cases, and in giving us the use of his yard. 



The soil in the richest parts of these ravines, which had 

 been washed down from the higher slopes of the Lomas, is 

 several feet deep, and appeared sufficiently good to be used 

 for the Wardian cases, in the event of its being foimd im- 

 possible to obtain soil from any more promising locality ; 

 and the great number of wild flowers which were growing 

 in it convinced me that it could not contain anything veiy 

 pernicious.^ 



The formation consists of granite, with veins of very pure 

 quartz; but the plains are covered wath large patches of 

 fine dust, consisting chiefly of silica, containing potash and 

 mica, with small quantities of the debris of the rocks asso- 

 ciated with the soil, which Admiral FitzEoy suggests may 

 have been the ashes ejected, at some remote period, from the 

 volcano of Arequipa. Near the sea-shore, and about half a 

 mile south-east of Islay, there is a very cm-ious result of the 

 constant action of the weaves, in two immense cavities hol- 

 lowed out of the rock, called the Tinajones (jars). They are 

 circular holes about thirty yards across, and of great depth, 

 separated from the sea by a wall of clifis not more than four 



■' The analysis of this soil, by Dr. Forbes Watson, gave the following result : — 



Water, and a little organic matter 7'100 



Silica, as silicate and as silex ."iO'SOO 



Peroxide of iron 12-100 



Ahuniua 12-300 



Lime 4-100 



Magnesia 2-100 



Soda 0-724 



Chloride of sodium 0-408 



Phosphoric acid 0117 



Carbonic acid 



Sulphnric acid 0-082 



99-081 

 Loss -319 



100-000 



