THE THEORY OF VOLCANOES.

New Zealand Mail, 17 September 1902, Page 19

THE THEORY OF VOLCANOES.

■AT-The theory of volcanoes given by Dr. „ j ?; la j er > Professor of Geology in Harvard University, is that they are occasioned by steam, the water absorbed by various means from the sea, or lakes, or siu lace drainage becoming heated in contac". wdh the molten matter below the earth s crust. It is to be borne in inind unit, when extremely heated rocks containing water are penetrated by a fault, tffe expanding steam will force tile whole mass m movement towards the place of escape—as in tho instance. 9! douga, where t-'o^ yeast fermentation produces gas, the material creeps in the direction of least resistance. When the rocks start on their cnlorced journey they are probably solid, kept in that stale hyjhe vast pressure of tne beds above them, "but as they arrive near the surface they become softened, and finally, it may be, as liquid as molten glass. The evidence goes to show that the lavas and ashes which are poured from the greater volcanoes are often derived fiom locations hundreds of miles away ironi the vent by which they escape. Thus while the materials thrown out by Etna have probably amounted to a bulk of more than 1000 cubic miles, the foundations of the cone Lave gradually risen since ejections began, until now its base is some hundred feet higher than at the beginning. This clearly indicates the remote derivation of the erupted matter. As regards Martinique and St. Vincent, tfao conclusions drawn by the professor are as follow:

“While the accident appears to have been in a geological sense relatively unimportant, the position of the town in relation to the cone, the neighbourhood of sea which barred flight, and the somewhat unusual swiftness in the development of the outbreak, combined to make it a very great calamity. “There are certain lessons to be drawn from the disasters of Martinique and St. \ lucent. The first of these is that the neighbourhood of r. volcano that has been so recently in eruption as to retain its shape in a well-preserved state is not a fit place for a city or other important seat of man’s endeavours. - The second concerns the importance of systematic and extended observations of volcanoes, with a view to an effective foretelling of approaching eruptions. So far, observations of this nature have been limited and imperfect. There is reason to believe that it will neither be difficult nor costly to obtain data such as would have spared thousands who died in the recent disasters. It is clearly not in the power of man to prevent the activity'of volcanoes, as he well may the vastly more destructive plagues of war' and disease; but lie may, by his understanding, lessen the evils they inflict, as he does those of the hurricane or the earthquake. It is well to note, however, that the calamities which may thus be avoided, though in their, nature appalling, constitute but an insignificant part of the sum of death and destruction that comes to man. Though this earth beneath our feet is the seat of Titanic forces, it d c als gently with its living tenants—far more gently than they with one another. That life here is the result of at least a hundred million years of uninterrupted progress shows that the interference of the powers of the under earth with the course of life has not been serious.”