34: T. A. Jag gar — Initial Stages of the Spine on Pelee. 



Art. III. — The Initial Stages of the Spine, on Pelee; by 

 T. A. Jaogar, Jr., Cambridge, Mass. 



Dr. Hovey's interesting studies'* of the remarkable spine 

 which has been developed on the summit of the new cone ,of 

 debris on Mt. Pelee, in Martinique, recall to the writer certain 

 notes and photographs made soon after the first eruption in 1902. 

 These notes are of some interest in the light of Hovey's dis- 

 coveries, and they are presented here as representing what is 

 perhaps the first record made in the field of the process of 

 spine-growth. A theory of origin for such spines was crudely 

 framed at the time, but many details were obscure. Hovey's 

 article has cleared up some of these points, and an explanation 

 of the phenomenon is here suggested, partly at variance with 

 the theory of the French geologists. f 



The First Observed Spine. 



On May 21, 1902, the most distinctive features of the inner 

 cone were its low relief relative to the walls of the gorge, and the 

 material^ of which it was composed. It appeared to be a heap 

 of scaly or crusty bowlders, "smouldering" in appearance, 

 brown dust clouds rising from the crevices between the frag- 

 ments. The cone had a rounded crest and its height above its 

 apparent base was not more than 400 feet. The old rim of the 

 basin at the head of the Riviere Blanche rose above it ; the 

 diameter of this basin appeared to be about 800 feet. 



On June 27th, 1902, from Carbet, the cone was seen to have 

 grown to a height somewhat above the rim of the gorge. The 

 mountain at that time was almost continuously capped with a 

 rain-cloud ; for a few minutes that afternoon, however, it par- 

 tially cleared, and the detail of the cone's slope was seen with 

 a Zeiss binocular to consist of large fragments of brownish 

 angular material resting on a bed of apparently finer gravel. 

 The reddish dust 'cauliflowers' accumulated about every half- 

 hour and rolled down the gorge of the Riviere Blanche from 

 the cone. Sometimes this phenomenon was followed by a low 

 rumbling roar. This suggested that avalanches of loose rock 

 and gravel were falling, either from the rim of the crater or 

 the slopes of the cone. The basin had certainly caved in more 

 or less since May 21st, for it was much wider, and the cone had 

 gained enormously in both height and breadth. From the 

 Carbet beach, at night, a bright incandescent streak was seen 



* E. O. Hovey, The New Cone of Mont Pele and the Gorge of the Riviere 

 Blanche, Martinique. This Journal, October, 1903, p. 269. 



•j* Hovey, loc. cit. p. 276. Lacroix, Comptes Rendus, Oct. 27 and Dec. 1, 

 1902. 



