nd stage. The geysers of the Yellowstone occur on a grand scale;
the eruptions are frequent, and the water is projected into the air to a
height of over 200 feet. Most of these are intermittent, like the
remarkable one known as Old Faithful, the Castle Geyser, and the
Giantess Geyser described by Dr. Hayden, which ejects the water to a
height of 250 feet. The geyser-waters hold large quantities of silica
and sulphur in solution, owing to their high temperature under great
pressure, and these minerals are precipitated upon the cooling of the
waters in the air, and form circular basins, often gorgeously tinted
with red and yellow colours.[11]

[1] J. W. Powell, _Exploration of the Canyons of the Colorado_, pp. 114,
196. Major Powell describes a fault or fissure through which floods of
lava have been forced up from beneath and have been poured over the
surface. Many cinder-cones are planted along the line of this fissure.

[2] Capt. C. E. Dutton. _Sixth Ann. Rep. U.S. Geol. Survey_, 1884-85.

[3] Dutton, _loc. cit._, chap. iv. p. 165.

[4] _Amer. Jour. Science_, vol. 3., ser. (1871). A beautiful map of this
mountain is given in the _Fifth Annual Report, U.S. Geol. Survey_,
1883-84. Plate 44.

[5] Daubeny, _loc. cit._, p. 474.

[6] Gilbert, _Monograph U.S. Geol. Survey_, vol. i. (1890).

[7] Powell, _Exploration of the Colorado River_, p. 177, etc. (1875).
Hayden, _Rep. U.S. Geol. Survey of the Colorado, etc._ (1871-80).

[8] Richthofen, _Natural System of Volcanic Rocks_, Mem. California
Acad. Sciences, vol. i. (1868).

[9] Geikie, _Geological Sketches at Home and Abroad_, p. 271 (1882).

[10] Prestwich, _Geology_, vol. i. p. 370, quoting from Richthofen.

[11] The origin of geysers is variously explained; see Prestwich,
_Geology_, vol. i. p. 170. They are probably due to heated waters
suddenly converted into steam by contact with rock at a high
temperature.

CHAPTER III.

VOLCANOES OF NEW ZEALAND.

One other region of volcanic action remains to be noticed before passing
on to the consideration of those of less recent age. New Zealand is an
island wherein seem to be concentrated all the phenomena of volcanic
action of past and present time. Though it is doubtful if the term
"active," in its full sense, can be applied to any of the existing
craters (with two or three exceptions, such as Tongariro and Whakari
Island), we find craters and cones in great numbers in perfectly fresh
condition, extensive