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seven or eight metres. The surrounding rocks^ 
which remind us of the cave of Fingal, at 
Staffa, in the Hebrides ; the contrasts of vege- 
tation^ the wild appearance, and the solitude of 
the place, render this small cascade extremely 
picturesque. On both sides of the ravine the 
basaltic columns rise to more than thirty metres 
in height, and on them grow tufts of cactus and 
yucca filamentosa. The prisms have generally 
five or six sides, and are sometimes as much as 
twelve decimetres in breadth ; several present 
very regular articulations. Each column has 
a cylindrical nucleus, of a denser mass than the 
surrounding parts ; these nuclei are as it were 
enchased in the prisms, which in their horizontal 
fracture offer very remarkable convexities. This 
structure, which is also found in the basalts of 
Fairhead, I have shown in the foreground of the 
drawing toward the left. 
The greater part of the columns of Regia 
are perpendicular ; though some very near the 
cascade, have forty-five degrees of inclination 
toward the east ; and farther on there are others 
horizontal. Each group, at the time of its for- 
mation, appears to have followed particular 
attractions. The mass of these basalts is very 
homogeneous. Mr. Bonpland remarked in them 
nuclei of olivine or granuliform peridot, sur- 
rounded with mesotype-zeolite. The prisms, 
and this fact deserves the attention of geologists. 
