The Pamphlet Collection of Sir Robert Stout: Volume 67
Appendix No. 1
Appendix No. 1.
On page 69, preceding, the opinion was hazarded that the rocks and scoria finally ejected from Tarawera and Ruawahia fissure were basic in character, and denoted that a change had occurred in the history of the vulcanicity of the district. A reference to the analyses below, which have been most kindly supplied by Mr. J. A. Pond, Colonial Analyst for Auckland, proves the truth of this to demonstration.
In order that this may the more clearly be understood, a synopsis of analyses of volcanic rocks has been added, which shows the means of a very large number, given in Clarence King's "Geology of the Fortieth Parallel," Vol. I., and which have been taken out specially for this purpose. An analysis of a typical basalt, copied from J. Bete Jukes' "Manual of Geology," is also given.
Whilst it would thus appear that basic rocks formed the final ejectamenta from the fissure, it would seem, from facts which have come to the writer's knowledge since the foregoing pages were written, that during the earlier stages of the eruption, matter which may yet prove to be molten acidic rock was also ejected. This matter is in the shape of irregular, highly visicular, masses of obsedian glass, and of beautiful glassy bombs, which have been found along the shores of Lake Rotoiti in considerable quantities. The latter are perfectly ovoid in shape, and as much as 2in. in the longer diameter, of a dark-brown or black colour, and so light that they, equally with the irregular masses, float on water. These symmetrical objects have the appearance of birds' eggs formed of dark glass, like that of a bottle. The native inhabitants of Hawaii give to the filamentous glass so frequently found near the crater of Kilauea the name of Pele's hair—Pele being the goddess of the mountain: it is suggested that these pretty globules of glass may with equal propriety be called "Tarawera's tears."
It is to be noted, however, with respect to these analyses, that none of the scoria, of which such large quantities are found on top of Tarawera, has been brought from there to be tested. The lapilli shown in the table is that scattered around the southern and western parts of the deposit; but there cannot possibly be any reasonable doubt that it came from Tarawera and Ruawahia.page 76 page 77