NOTES ON BRAZIL. 



2S7 



On closer inspection I found that the whole mass was composed of 

 Laminas, which had acquired so much adhesion, that pieces miglit be 

 taken out nearly as large as our half-crowns. I endeavoured next to find 

 how and in what number these Laminas were formed. *By ascertaining 

 how many of them were contained in an inch, I concluded that the mass 

 must be, at least, equal to the number of days in fifty years, and that 

 the accumulated sand of each day was consolidated by the calmness and 

 the dews of the succeeding night ; a variety of tints being observabit 

 in them, as in sand-stone in general, probably according to the measure 

 of moisture employed in their formation. The appearance corresponded 

 exactly with that of the micaceous laminated sand-stone of England ; so 

 that it seems that sand, gathered by wind alone, would produce this 

 kind of stone, and in fifty years might acquire consistency enough to 

 enable the mass to support a face of ninety degrees. 



Dried branches of shrubs are frequently found upon the sandy 

 wastes, which once enjoyed moisture enough to enable them to vegetate. 

 These disappearing, as did the wood, clay, and twigs, with which my 

 experiments were made, would continue to retain their form, if the 

 congregated sand ever hardened into stone; this may account for the 

 appearance of such substances embedded in rocks. On like principles 

 the marks of foot-steps in the sand-stone of England may be accounted 

 for. My horse's feet, in passing, frequently broke the strata to the 

 depth of six inches ; and shoidd the surrounding part ^ever be consoli- 

 dated, the impression of his foot v>rould remain, to A'^atever depth it 

 might afterward be buried. After rain, I observed the same kind of 

 depressions, on the surface of these deserts, as are found in much of the 

 Yorkshire sand-stone ; these are overwhelmed as the sand dries, and 

 begins again to move, but they are not obliterated, and remain to excite 

 the curiosity of ages to come. 



These resemblances between the phenomena of sand-hills, which are 

 known to have been raised by the wind alone, and those which appear in 

 the consolidated ridges of Europe, might be traced, I think, in the 

 deserts of Africa and Asia. Perhaps enough has been said to stimulate 



