The daily morning journal and courier., 1902-06-05
THE MYSTERIOUS VOLCANO
4 VERT INTERESTING LITTLE
 LECTURE
By Very Competent Goologist Of
 Columbia.

| or Etna, the quleSCent but SlgnlnCant crater of Vesuvius, and the partially submarine vent of Santorin. There Is
 reason for thinking that much of the vivid imagery of the Book of ReVela- tlons was suggested to St. John because he witnessed from Patmos an outbreak
 of the lats named, which is barely nine ty miles away. Certain it ia that a recorded eruption times with his life on the little isle as closely as the ancient records enable us to reckon the equiva-
 Tents.
 But of all the historic eruptions none
 have sent abroad such a thrill of hor-
 TOT as those of the last two weeks in the Lesser Antilles. Nesuvius may have slain IS many thousands in the Pom pelian catastrophe, but weeks were re- quired to spread the tidings over even small part of the civilized world; whereas to-day, within a few hours, people all around the globe are aghast at the terrible happenings, and those
 who live near still active cones are won
 dering what dread possibilities may lie
 hidden within them. ...
 Volcanoes are closely bound up in
 their causes and action with the con-
 ditions which prevail in the interior of
 the earth While all geologists, who
 are naturally conservative in their
 thinking, realize the uncertainties of the problem, yet from various lines of
 evidence reliable conclusions have been
 drawn.
 Tn the first place, all the experience
 which has been gained in deep mines and by lowering self-registering ther- mometers into deep bore-holes goes to show that the temperature increases at pretty regular rate with descent. It varies in different regions On Kewec- naw Point, Lake Superior in the cop per mines, now between 4,000 and 5000 feet deep, the increase Is not far from one degree Fahrenheit for each 100 to 106 feet. This is the lowest rate vet measured In other places it is fifty feet or less for a degree, and a fair av- craze is perhaps sixty. If there are lava sheets under the surface. not yet cooled, the rate is abnormally high, and such exceptional cases must be reject ed.
 A simple calculation will show that, with an increase of one degree for sixty
 
 eighty-eight degrees. and within thirty miles it would be over 2,500 degrees, as temperature sufficient to melt ordinary lavas. Yet thirty miles is less than one per cent. of the radius of the globe
 An eruption seldom breaks out with out preliminary earthquake shocks emissions of steam from the crater, and minor explosions which serve as warnings. The earthquakes are prob ably produced by the upward move ment of the molten rock in the Assure. and by it's forcing it's way through plugged or narrow passages with at tendant explosions of steam. They may be due in part to earth-movements along the fssure-that is, by the slip ping down of one side; but this is less likely As the advance guard of the on- tide reaches the vent it's con- fined vapors go off with explosions and rise like clouds in the air Neighbor- ing masses of rock, both solid and liquid, are blown to dust and scattered abroad, coarser fragments are inter- and rain of pumice or scoria falls on the neighboring country. If the volcano is just beginning, it builds
  1t is an old one, a cone of bedded frag- ments, or radiating dykes, and of mingled sheets is already in existence, Finally, if the eruption is a very vio- lent one, some terrific explosion blows out one portion of the crater, or breaks q huge rent in it's side through which the hot, steaning tide courses to the Iowlands The outburst usually marks the continuation, and with still violent but waning force the explosions con- .inue until they die away, perhaps for good, perhaps for centuries, perhaps but few years or months. Not all follow just this course, but t is the rule
 The violence of an outbreak is in l most cases proportional to the preced ing period of quiescence. Thus, if a l cone which has been long inactive sud- 1enly breaks out, there will be more accumulated energy available than if t had gradually and more or less con- tinuously exhausted it's supplies. Ne- suvius for example, was quiescent from the period of the earliest historic rec 1rds until 70 A. D., an interval of at east 500 years. That is was an old | crater, however, no one could doubt. | Suddenly came the Pompeian eruption | ,f d degree of violence that has not l been attained since in nearly 1,S00 years l if almost continuous activity.
 Now let us apply these generalities to l he Lesser Antilles. We find on the l north and south sides of the Caribbean Sea the two lines of uplift represented II the first case of Cuba, Hayti, Porto | Rico and the Danish West Indies. An l ,ient eruptive rocks are not lacking, | put they are only subordinate portion | If the land The South American ! with it's mountains back l rom the coast, is another ancient line | if uplft. Connecting these two on the 1 ,ast are the Lesser Antilles, almost | without exception of volcanic rock and marking a line of vents. Since 1872 no | ,ruptive activity has been seen, and in he crater of Mount Pelee small ake existed. Suddenly after this period of quiescence arthquakes are felt, clouds of steam ssue from the crater, and later fine lust and comminuted rock are blown nj and descend in showers A flood of |