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Not much was said about the theory of volcanoes, but Debenham touched on American theories the melting out from internal magma. There was nothing much to catch hold of throughout, but discussion of such a subject sorts one's ideas. Saturday, June 17. Northerly wind, temperature changeable, dropping to -16°. Wind doubtful in the afternoon. Moon still obscured it is very trying.
Faiths melt; churches dissolve; morals fade; bonds fail; a universal magma of emancipated opinion seems to take the place of old-established dogma. The squires and the parsons of the period call them scribes or augurs wring their hands in despair, and cry aloud that they don't know what the world is coming to. But, after all, it is only the chrysalis stage of a new system.
It now remains for us to consider what may be the condition of the interior molten magma; and in doing so we must be guided to a large extent by considerations regarding the nature of the extruded matter at the surface. Now, observation shows that, as bearing on the subject under consideration, lavas occur mainly under two classes as regards their density.
In the majority of cases the lavas consist of a mass of crystals floating in a liquid magma, and the distension of such a mass by the escape of steam from its midst gives rise to the formation of the rough cindery-looking material to which the name of "scoria" is applied.
In crystallizing from the magma, they entrapped sufficient numbers of particles of the higher orders to give them the characteristics which you have observed. The impurities, however, are not sufficient in quantity to offer a point of attack to any ordinary reagent." "But how could such material possibly be formed?"
What's coming up now is just small debris from the nuclear blast. When the shock-waves get down far enough to crack things open, the gas'll come up, and then steam and ash, and then magma." "Well, even this was worth staying over for," the girl said, watching the screen. "You going on to Ullr on the City of Canberra?" Lourenço Gomes asked.
The universality of these phenomena all over the surface of our globe, in past or present times, indicates the existence of a general cause beneath the crust. On the other hand, the similarity of volcanic lavas over wide regions is strong evidence that they are drawn from one continuous magma, consisting of molten matter beneath the solid exterior crust.
"You must be aware," continued Cosmo, addressing them particularly, "that it has been demonstrated that the continents and the great mountain ranges are buoyed up, and, as it were, are floating somewhat like slags on the internal magma. The mean density of the crust is less under the land and the mountains than under the old sea-beds. This is especially true of the Himalayan region.
As time went on, and the heat radiated into space from the surface of the globe, while at the same time slowly ascending from the interior by conduction, the crust necessarily contracted, and pressing more and more on the interior molten magma, this latter was forced from time to time to break through the contracting crust along zones of weakness or fissures.
It was within the precincts of the City, at the metropolitan church of St. Paul's, that the articles of Magma Charta were first proposed and accepted by acclamation, the citizens binding themselves by oath to defend and enforce them with their lives. Nor was it for themselves alone that they were prepared to shed their blood.
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