Eruptions on Martinique and St Vincent 433 



great amount of water contributed to the 

 atmosphere as steam, and, second, the 

 vast amount of dust blown into the air, 

 each particle of which serves as a center 

 for condensation. The process of fash- 

 ioning the topography throughout the 

 extensive areas from which all vegetation 

 has been removed is greatly accelerated. 

 This more rapid erosion will, no doubt, 

 continue until the surface is again plant- 

 clothed. 



The volcanic eruptions have claimed 

 so much immediate consideration from 

 the several geologists and geographers 

 who have visited the stricken islands 

 that the indirect geographical changes 

 resulting from them have not received 

 the attention they deserve. Not only 

 the pulsating streams of steaming water 

 and their occasional great discharges of 

 hot mud demand detailed study, but the 

 way in which the undermining of banks 

 of loose debris leads to landslides, the 

 development of consequent and subse- 

 quent streams, the manner in which 

 streams develop and rapidly pass from 

 youth to old age, etc., deserve to be 

 carefully recorded. The streams are not 

 only eroding but depositing. Deltas are 

 being formed and additions made to the 

 land. The final resting places of the 

 fresh debris which fell on the islands 

 will be in the adjacent sea, where great 

 quantities of fragmental volcanic mate- 

 rial is being spread out to form stratified 

 tuffs. 



Waves in the Sea. — Reports have ap- 

 peared in the newspapers, from time to 

 time since early in May, of so-called 

 tidal waves. As is well known, the 

 waves referred to have no connection 

 with the tides, but are similar to those 

 occasionally accompanying earthquakes. 

 So far as can be judged, however, the 

 unusual waves that have recently broken 

 on the shores of Martinique and St Vin- 

 cent have not been due to movements 

 in the earth's crust, such as commonly 

 produce earthquakes, although some of 

 them may have been of that nature. 



The waves referred to have been caused, 

 in most instances, by the disturbances 

 produced in the water of the sea by the 

 blasts of dust-laden steam that have 

 swept down from the craters of Mont 

 Pelee and Da Soufriere. Similar waves 

 have also been generated by the entrance 

 into the sea of stupendous mud flows, or, 

 perhaps more properly, avalanches of 

 rock debris and water, like the one 

 which destroyed the Guerin sugar fac- 

 tory on May 5. Again, landslides have 

 occurred in the loose deposits on the 

 Caribbean shores of both Martinique and 

 St Vincent, and similar slides, as indi- 

 cated by the breaking of telegraph ca- 

 bles, have probably taken place on the 

 steep submerged slopes of the mountains 

 whose summits form the islands men- 

 tioned. In these several ways, waves in 

 the sea appear to have been generated, 

 but in all instances they have been low 

 and but little damage from them has 

 resulted. The earthquake shocks that 

 accompanied the recent eruptions have 

 been comparatively light, and, so far as 

 can be judged, not of such a nature as 

 to cause large waves in the adjacent sea. 

 The earthquake shocks, however, may 

 and probably did bring about the descent 

 of some of the landslides on the margin 

 of the sea and on the steep submerged 

 slopes, and in this way are indirectly ac- 

 countable for some of the sea waves. 



Landslides. — The landslides just re- 

 ferred to occurred principally on the 

 west side of St Vincent, to the north 

 of Chateaubelair, where strips of nearly 

 flat alluvial land, adjacent to the sea, 

 have disappeared, leaving fresh bluffs 

 of loose debris some thirty or forty feet 

 high. It has been suggested that this 

 disappearance of land, and in one in- 

 stance of the site of a village, was due 

 to movement along a fault — that is, the 

 subsidence of the rocks on one side of 

 a deep fracture in the earth's crust — 

 but the evidence does not seem to sus- 

 tain this hypothesis. The lands that 

 have disappeared, as shown by the es- 



