GEOLOGICAL CHARACTER. 13 
Strata, or veins of basalt, are frequently met with 
in all the islands: they usually occur in mountains 
of amygdaloid rock, or cellular volcanic stone. The 
veins or strata are seldom, if ever, horizontal, but 
generally perpendicular, oblique, or curved. One 
of the most extensive and curious of these, 1s 
piled up in stupendous grandeur near the head of 
Matavai valley, and overhangs the mountain-stream 
that flows around its base. There are several in 
Huahine, which I] have examined. One, on Hua- 
hiné-iti, intersects, in an oblique direction with an 
inclination towards the west, a large mass of pumice 
and ancient porous lava; another, situated on the 
south-east front of Vaiorea, in the midst of a pile 
of more compact and apparently recent lava, is 
nearly perpendicular; both resemble very much 
the whinstone dykes in the north of Ireland. The 
crystallized columns or prisms are very perfectly 
formed, and are laid at right angles with the posi- 
tion of the vein they compose. The greater part 
appear pentangular, but their shape and size is 
not uniform. On comparing a very small trian- 
gular crystal, which I brought from Vaiorea, with 
one which I procured from the dykes near the 
Giant’s Causeway, the substance and structure 
of each appeared nearly the same. 
_ Although so many unequivocal appearances of 
the action of fire occur in almost every island, 
especially m those in which I have had the best 
opportunity of pursuing inquiries, relative to the 
probable origin of the islands, viz., Huahine, and 
the small adjacent island of “Vaiorea, where the 
cellular rocks often present a surface, exactly 
resembling that of the recently ejected and scarcely 
indurated lava in Hawaii; I never met with any 
cavern, aperture, or other formation resembling a 
