Volcanic Disturbances in West Indies 285 



noon the same day, and the following 

 day returned to Fort de France. On 

 Ma)' 31 the good ship sailed for home, 

 bearing, of your commission, Professor 

 Hill and myself, Commander Borchgre- 

 vink having previously started north- 

 ward on a passenger steamer. 



The morning we bade good-bye to 

 Consul Ayme, at Fortde France, dawned 

 unusually fair. There was not a cloud 

 in the sky except the vast columns of 

 steam rising from the still active crater 

 of Mont Pelee, which rose, as deter- 

 mined by angulation by Lieutenant 

 Bernadou, to a height of 15,000 feet. 

 On passing the site of St Pierre we had a 



last but distant view of the dead city. At 

 the end of a pleasant homeward voyage 

 the Dixie once more dropped her anchor 

 in the harbor of New York on June 6. 

 This hasty letter I trust will serve to 

 show the members of the National Geo- 

 graphic Society, at least in a general 

 way, the nature of the observations their 

 agents were able to make ; but I trust 

 it will in time be followed by a critical 

 discussion of the very characteristic ex- 

 plosive volcanic eruptions which deso- 

 lated such large portions of the other- 

 wise charming islands we visited. 



University of Michigan, 



June 20, 1902. 



VOLCANIC ROCKS OF MARTINIQUE AND 



ST VINCENT 



Collected by Robert T. Hill and Israel C. Russell 

 Described by J. S. Diller 



SOON after the disaster of St Pierre 

 the U. S. Weather Bureau sent to 

 the Geological Survey for exam- 

 ination a bit of volcanic dust collected 

 May 8, 1902, aboard the steamship Coy a, 

 185 miles southeast of Barbados. To 

 this was added later some of the vol- 

 canic sand which fell on Barbados, and 

 the source of the material, whether from 

 la Soufriere, on St Vincent, or Mont 

 Pelee, on Martinique, both of which were 

 in eruption about the same time, was 

 a matter of much interest. Therefore 

 when I received from Professor Hill for 

 study the material which he collected at 

 Martinique during his investigations for 

 the National Geographic Society, I an- 

 ticipated much pleasure in searching for 

 the source of the dust. 



Professor Hill's collection embraces 

 33 specimens ; 30 came from Martinique 

 and 3 from St Vincent. Of the Marti- 



nique specimens, 18 resulted from erup- 

 tions long antedating the present vol- 

 canic activity, 6 are ejecta of recent 

 date, and 6 are " fumarole deposits" 

 on the slopes of Mont Pelee. 



The rocks of Martinique are remark- 

 ably simple, and belong to well-marked 

 types of andesite, with normal variations 

 representing traces of earlier conditions 

 deep within the earth. The great vol- 

 canic belt along the axis of the two con- 

 tinents from Cape Horn through the 

 Americas to Point Barrow is composed 

 largely of this kind of volcanic rock, 

 which indeed gets its name from the 

 Andes Mountains, where it was early 

 discovered. 



In the prevailing rock of the collection 

 hypersthene is the characterizing ferro- 

 magnesian silicate, and it is commonly 

 associated with some augite. In closely 

 allied specimens hornblende comes in 



