Geology and Mineralogy. 313 



lives commissioned by the National Geographic Society to inves- 

 tigate the phenomena attending the cataclysms. The number is 

 enriched by the notes by J. S. Diller on the volcanic rocks collected 

 by Hill and Russell; by a chemical discussion by W. F. Hille- 

 brand of analyses of ejecta from the two islands, and by a com- 

 pilation by James Page of the reports of vessels as to the area over 

 which the dust from the eruptions was distributed. The number is 

 well illustrated with four maps and nineteen photographs. Four- 

 teen of the latter are from excellent negatives taken by Russell. 

 Hill's report opens with a brief general statement of the geog- 

 raphy and q;eology of the whole chain of the Windward Islands 

 or Lesser Antilles, which are almost entirely volcanic in charac- 

 ter, with the exception of Barbados. He holds that the volcanoes 

 of these islands date back to Eocene time, at least; that the 

 greater masses of the present volcanic heights were piled up 

 before the Pliocene, and that "the present craters are merely 

 secondary and expiring phenomena." In discussing the present 

 eruption, after relating the premonitory events of the preceding 

 fortnight. Hill gives in detail the history of the great outburst of 

 May 8 as derived from the accounts of eyewitnesses, and then 

 elaborates his personal observations, which were made between 

 May 21 and 30. He holds that the eruption which destroyed St. 

 Pierre came from a crater low down on the southwest slope of 

 Mt. Pelee, two miles from the northern limit of the city and a 

 mile and a half from the sea, which he calls the " Soufri^re " or 

 " Etang Sec " crater. He considers the mud-flows to be primary 

 phenomena of the eruption and to have come from this crater 

 and from several "mud-craters" on the slopes of the mountain, 

 the sites of some of which had long been known as thermal 

 springs. 



Hill calculates that only 12*5 square miles, or one-twentieth of 

 the total area of Martinique, have been seriously affected by the 

 eruption. Ko great geological changes have been brought about, 

 but the configuration of the summit and the outline of the sea- 

 coast have been changed somewhat. He says, " There have been 

 no lava flows whatsoever. . . . No true bombs have been ejected 

 or molten rock in any form." His conclusion is that conflagra- 

 tion and death in St. Pierre may ultimately be explained by either 

 of two theories : 



(1.) The heat-blast theory. This hypothesis assumes that the 

 lapilli, gases, and steam of the ejected cloud were sufficiently hot 

 to have inflamed the city and destroyed the people by singeing, 

 suffocation, and asphyxiation. It does not account for the forces 

 exerted radially and horizontally, nor for the flame. 



(2.) The aerial-explosion theory. The explosion of gases within 

 the erupted cloud after their projection into the air would account 

 for all the phenomena observed. 



Russell's report takes the form of a letter to the Society. He 

 does not subscribe to the opinion that the inhabitants of St. Pierre 

 were asphyxiated by noxious gases or killed by a gas explosion. 



