on Basalt , &c. 
3U 
The immense magnitude of some basaltic columns, the ex- 
treme regularity of their prismatic configuration, and the peculiar 
structure of their articulations, have directed the attention of 
naturalists to them, much more than to any of the other rocks 
which affect the columnar form. Yet many of these are suffi- 
ciently remarkable to deserve more particular notice than has 
generally been paid to them ; and they afford most illustrative 
proof, that this configuration is not confined to either the aqueous 
or igneous formation; for some lavas, universally allowed to 
•• commonly of a single shoot, which is sometimes 60 feet high ; others are divided by 
" articulations, which are from one to six feet asunder. 
“ I have more than once observed a large column divide into several smaller in its 
" upper part. The columns are generally larger near the top than the bottom of the 
“ stream of lava, because they subdivide ; and they are always least in that part of the 
r< stream of lava which first entered the water, the refrigeration being more prompt, 
“ and its effects more marked. Sometimes the columns are placed perpendicularly 
“ side by side, and form vertical walls, which are sometimes more than 100 feet high, 
et and a league long ; sometimes they are heaped obliquely, horizontally, and in all 
*« positions. Some, without being divided in their length, are larger at one end than 
«* the other ; and then they are arranged like wood piled up, with all the small ends at 
“ one side ; sometimes they are formed into pyramidal bundles, by parting from a 
*• common centre ; and, finally, there are some which, by their reunion, form large 
** balls. These radii of lava, which are rather pyramidal than prismatic, resemble 
«' those of the globular pyrites, striated from the centre to the circumference, which 
“ are found in the chalk of Champagne. 
“ On the shore of la Trezza, near the Mole, there is a very curious group of little 
articulated prisms, which issue from a common centre, and form fasciculi singularly 
“ twisted. The articulations are marked, but the species of vertebrae do not separate. 
«* In the heart of the mountain on which stands the Gastello di Jaci, there are large 
“ balls, from two to four feet in diameter, resembling in form the large pyrites in the 
“ chalk of Champagne. These balls of lava are formed of pyramidal columns, united 
“ by their points in a common centre.” Catalogue des Laves de l' Etna, page 453. 
The division of the upper part of basaltic columns into several smaller ones, has also 
been observed in the basaltic columns of Fairhead, by Dr. Richardson. See 
Nicholson’s Journal, 4to. Vol. V. page 321. 
MDCCCIV. S S 
