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Twenty-three miles around stretched the dizzy wells of the crater. We stood on the edge of the nearly vertical western wall, and the floor of the crater lay nearly half a mile beneath. This floor, broken by lava-flows and cinder-cones, was as red and fresh and uneroded as if it were but yesterday that the fires went out.
To the south of the high plateaux of Utah are many minor volcanic mountains, now extinct; and as we descend towards the Grand Cañon of Colorado we find numerous cinder-cones scattered about at intervals near the cliffs.
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. Capt. C. E. Dutton. Sixth Ann. Rep. U.S. Geol. Survey, 1884-85. Dutton, loc. cit., chap. iv. p. 165. Amer. Jour.
But he, at the same time, clearly saw that there was no evidence of the occurrence of great deluges of lava along such fissures; he showed how the most remarkable plateaux, composed of successive lava sheets, might be built up by repeated and moderate ejections from numerous isolated vents; and he expressly insists upon the rapidity with which the cinder-cones around the orifices of ejection and the evidences of successive outflows of lava would be obliterated by denudation.
This mountain forms the culminating point of a wide volcanic tract, over which are distributed numberless vents of eruption. Scores of such vents generally cinder-cones are visible in every part of the plateau, and always in a more or less dilapidated condition.
The cinder-cones, the smallest over four hundred feet in height and the largest over nine hundred, seemed no more than puny little sand- hills, so mighty was the magnitude of the setting. Two gaps, thousands of feet deep, broke the rim of the crater, and through these Ukiukiu vainly strove to drive his fleecy herds of trade-wind clouds.
There was a gallop across a level stretch to the mouth of a convenient blow-hole, and then the descent continued in clouds of volcanic dust, winding in and out among cinder-cones, brick-red, old rose, and purplish black of colour.
Extensive lava-fields, surmounted by cinder-cones, occupy the plateau on the western side of the Grand Cañon; and, according to Dutton, the great sheets of basaltic lava, of very recent age, which occupy many hundred square miles of desert, have had their sources in these cones of eruption.
From their account we learn that the Isthmus of Auckland is one of the most remarkable volcanic districts in the world. It is characterised by a large number of extinct cinder-cones, in a greater or less perfect state of preservation, and giving origin to lava-streams which have poured down the sides of the hills on to the plains.
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