PRESENT CONDITION OF MONT PELE 567 



In November the great spine was observed to be slowly rising again, a move- 

 ment which was checked in the latter part of the month. The official reports, as 

 published in the "Journal Officiel de la Martinique," from which the data printed 

 in this notice were obtained, are somewhat obscure, but it seems that there has 

 been a net loss of about 80 meters during the year. 



The valley between the new cone and the remains of the ancient crater, which 

 was estimated to be about 200 feet deep in March, 1903, has been greatly reduced 

 in depth by the debris thrown into t by the spasmodic partial demolition of the 

 rising dome. 



Frequently luminous points were observed in the dome at night, and the almost 

 constant gentle discharge of steam was varied at irregular intervals by explosions 

 of reddish or whitish dust-laden steam clouds. Some of these clouds descended 

 into the upper valley of the Riviere Blanche, others toward Precheur, and a few 

 expended their force toward the east, over the site of the Lac des Palmistes. On 

 April 26 the ascending column of steam sometimes attained an elevation of 3,000 

 meters. An equal altitude was attained by the steam clouds in the latter part of 

 September and again in November and December. 



The author discussed briefly the origin of the dome and spine, referring to the 

 three theories that have been advanced to account for it. He dismissed the idea 

 that it had been formed through the piling up of plastic fragments,* by calling 

 attention to 



(1) The shape of the mass and its component parts as not being those of an 

 exogenous cone ; 



(2) To the appearance of the whole, which was and is that of a relatively homo- 

 geneous though much rifted rock-mass ; 



(3) To the corrugated northeastern surface of the spine of 1902-1903, which pre- 

 served vertical striatums probably due to friction against the wall of the conduit ; 



(4) To the fact that the scores of major and minor eruptions which had been 

 observed had uniformly thrown their ejecta beyond the rim of the great crater 

 surrounding the dome or down the debris slopes into the valleys of the Blanche, 

 Claire, La Mare, and Precheur rivers. 



The author considers untenable the second theory also, which is that the dome 

 and spine are the elevated plug of ancient lava supposed to have closed the con- 

 duit before the activity of 1902 began. t The volcano of mont Pele is a composite 

 affair, made up of beds of solid lava and frag mental debris (tuff), the latter by 

 far predominating. 



It is entirely probable that some of the previous eruptions have been of the 

 character of the present outbreak and that some of the massive lava beds now in 

 evidence originated as massive solid exudations. 



The causes of the inception and cessation of volcanic activity are not sufficiently 

 well known to assert that a plug of solid lava necessarily fills the conduit of a 

 volcano at the quiescence of a vent. 



The total elevation of dome and spine, had no losses occurred, would probably 

 have amounted to not less than 6,000 feet above the bottom of the old crater. This, 

 according to the " elevated plug " theory, would predicate the presence of a stopper 

 of cold or, at any rate, solid lava at least 6,000 feet in vertical measuremeut. The 



*T. A. Jaggar, Jr.: The initial stages of the spine on Pelee. Am. Jour. Sci., iv, xvii, 39. Jan. 

 19(H. 

 t A Heilprin : The tower of Pelee. 1904. J. B. Lippincott Co. 



