ORGAN MOUNTAINS. 491 



scended as slowly as we had mounted the serra, stopping 

 almost at every step to gather plants, to examine rocks, to 

 wonder at the strange position of the immense boulders 

 hanging often just on the brow of some steep declivity. 

 I wandered on beyond the others and sat down to wait for 

 them on the low stone wall, forming a parapet on the edge 

 of the road. Directly before me rose the bare, rocky sur- 

 face of one of the great peaks ; a vapory white cloud hung 

 midway upon it ; shadows floated over it. On the other 

 side I looked down upon wooded valleys and mountains in 

 strange confusion, while far below, stretching out to the sea, 

 lay the billowy plain tossed into endless soft green waves. 

 The stillness made the scene more impressive, the silence 

 being only occasionally broken by the click of hoofs, as a 

 train of mules came cautiously down the flagged road. 

 While I sat there a liteira passed me slung between mules ; 

 a mode of travelling fast disappearing with the improve- 

 ments of the roads, but still in use for women and children 

 in certain parts of the country. We stopped to breakfast at 

 a little venda about half-way down the serra ; here the boul- 

 ders are most remarkable from their great size and singular 

 position. We reached the inn at the bottom of the serra 

 between two and three o'clock, and are now sitting in the 

 little piazza, while a drenching rain, which fortunately did 

 not begin till we were under shelter, swells the stream near 

 by, and is fast changing it to a rapid torrent. I will add 

 here such observations respecting the geological structure 

 of this mountain range as Mr. Agassiz has been able to 

 make in our short excursion. 



" The chain is formed by the sharp folding up of strata, 

 sometimes quite vertically, in other instances with a slope 

 more or less steep, but always rather sudden. To one stand- 



