25§ 



NA TURE 



[January 15, 1903 



were observed, and two were brought back to New York, 

 one of which is n iw on exhibition in the American Museum. 

 The large-it ejected block noted was one upon the surface of 

 the mud-flaw between the Blanche and Seche rivers, less than 

 200 yards from the sea-coast and about three miles from the 

 crater. Its dimensions are 30x24x22 feet, and it is of the 

 light grey ancient aniesitic lava, to be found in all places near 

 the sammit of the mountain. Many other great boulders, some 

 of which are of nearly half the dimensions of the one just 

 described, lie near by. 



Four ascents of Mont Pelee, in the course of which the crater 

 rim was traversed fr am the great chasm on the south-west along 

 the southern and eastern edge, abmt twj-thirds of the way 

 around the circle, and the remainder also of the rim was clearly 

 seen, the author was enabled to form a reasonably definite idea 

 of the centre of activity of the volcano and whit was going on 

 therein. The crater is somewhat oval in shape, with the longest 

 axis stretching north-east and south-west, and the highest point 

 of the rim is on the north-east, and is what is left of the peak which 

 isknjwnas Morne Lacroix. The average between the readings 

 of two barometers (me being in the hinds of Mr. Geirge C. 

 Curtis, the companion of the author) determined the altitude of 

 this peak as 4200 feet above the sea, the original height given 

 upon the chart being 4428. The lava bed, forming what m >y 

 be considered the rim of the crater on the south-east side of the 

 gash, is 3350 feet above tide, while the real bottom of the gorge 

 where it issues from the crater is 500 or 600 feet less in altitude. 

 From this lava bed the rim rises rapidly (30 to 35 ) to about 

 3750 feet above tide and then more gradually along the southern 

 edge, until 3950 feet is reached on the eastern rim. The north- 

 west side of the south-western gash is formed by a pinnacle of 

 ancient lava, which appears to be about 4000 feet above the sea. 

 From this point the rim drops somewhat toward the north, but 

 gradually rises again toward the east until Morne Lacroix is 

 reached again. This crater is estimated to be about half a mile 

 across. The breadth of the rim varies from a mere knife-edge 

 on the south, west, north and north-east sides to a sloping 

 plateau 50 to 100 yards wide, on the eastern side. This 

 plateau is the site of the shallow body of water known as Lac 

 des Palmistes. 



This lake basin was empty when visited by Prof. Heilprin on 

 June 1, but was filled with dust and ashes when the author 

 and Mr. Curtis visited the spot on June 18, 20 and 26. 

 The author considers that the body of water known as ittang 

 Sec, and not the Lac des Palmistes, was the real crater lake of 

 Mont Pelee. The eruptions of the year 1902 have been for 

 the most part from a vent which opened within the large crater 

 at the head of the great gorge in the side of the mountain and 

 just west of Etang Sec. The activity has built up a cone the 

 top of which at the time the author left the island;, July 6, 

 was not less than 4000 feet above the sea, indicating a growth 

 of 1600 to 1703 feet within the two months of volcanic action 

 which had then taken place. There was a crater visible in the 

 top of this inner cone the breadth of which can only be guessed 

 at as being about 400 feet. Measurements of the angle of slope 

 of the outer side of the cone determined it to be 38 to 40", but 

 there are precipitous portions. The material which rolls and 

 slides down the south-west side of this c me continues directly 

 into the cation of the Blanche river. Tne steep-sided valley 

 formed by the inner cone and the inner slopes of the great 

 crater is a continuation of the gorge of the Blanche and rises 

 rapidly from the south-western gash to the base of the rocky 

 precipice of M irne Lacroix, where it may be 800 feet in depth. 

 The valley probably continues round the northern side of the 

 inner cone, rising in a spiral, for it appears at an elevation of at 

 least 3600 feet on its eastern side between the inner cone and 

 the rim of the crater on the north-west side of the great gtsh. 

 Tnere seemed to be a second centre of eruption of considerably 

 less activity within the crater near the base of Morne Lacroix. 



The history of the present series of eruptions may be 

 epitomised somewhat as follows: the gradually returning 

 activity of the volcano began to make itself very manifest in the 

 latter part of April, since visitors to the crater found warm 

 water in the basin of the Etang Sec on the 25th of that m >nth, 

 and the lake was "deep.'' Calumnsof dust-laden steam rose 



torn an opening within the old crater on the east side of the 

 tang Sec and from one on the west side of the same basin, and 

 cones rose about these openings. Water in large quantity 

 collected in the old lake basin, assisted, perhaps, by a dam 

 formed across the gorge by the ejecta from the western crater. 



The water was heated by the action of volcanic forces. On May 

 5 the heated waters of the crater broke through this dam and 

 rushed, as a deluge of mud and boulders of all sizes, down the 

 gorge of the Blanche river, and overwhelmed the Guerih 

 sugar factory, which was situated at the mouth of the stream. 

 On May 8 began the series of great explosions which have sent 

 steam, laden with sulphurous gases, dust, ashes and stones, again 

 and again over the south-west slope of the moun'ain with the 

 violence of a tornado, several times reaching to St. Pierre and 

 beyond. The author would explain the blasts in the same 

 way as in the case of St. Vincent, but the great gash in the 

 side of the crater of Pelee and the position of the neighbour- 

 ing ridges concentrated the force of the explosions in a certain 

 direction and along a comparatively narrow zone— and the city 

 of St. Pierre with its 26,000 inhabitants and thousands of 

 refugees lay in an amphitheatre, a regular atl-de-sat, directly in 

 the path of the blasts. 



The ruins of the buildings in St. Pierre, the prone trees of 

 the city, the dismounted guns in the batteries of Morne d'Orange 

 and Pointe Ste. Marthe, the position of the iron statue of Notre 

 Dame de la Garde upon the edge of the bluff below and fifty 

 feet from its pedestal and many other circumstances, are the 

 evidences that a blast of tornadic violence swept over the city of 

 St. Pierre from the direction of the crater of Mont Pelee. The 

 degree of destruction diminishes from north to south, and the 

 amount of volcanic ash and stones deposited upon the city 

 becomes less and less in the same direction. 



The causes of death on Martinique were the same as on 



Fig. 3. -rQufll ter-inch ho Ler-iron tanks in a distillery in the Fort (Juartier 

 of St. Pierre, showing holes made by bombardment of stones from 

 Mont Pelee eruption. Photo by E. O. Hovey. 



St. Vincent, with the addition of crushing beneath falling walls 

 and other objects and cremation in burning buildings. In con- 

 nection with the eruptions of both volcanoes, the lack of 

 respirable air probably caused many deaths. 



The author came to the conclusion that there were no real 

 craters or centres of primary eruption anywhere on Mont Pelee, 

 outside of the great crater, though there has been much secondary 

 action along the lower portion of the Blanche, Seche, Falaise, 

 Grande and Piecheur rivers and other of the streams the sources of 

 which aiehighup upon the slopes of the mountain. The secon- 

 dary action was due, as in the Wallibou Valley and elsewhere on 

 St. Vincent, to the admission of water to the heated interior of 

 great accumulations of volcanic ash. Mud-flows and mud- 

 torrents have been very numerous down the gorges of these 

 streams and on the intervening plateaus. Some of these flows 

 have been due to the breaking of the temporary dams caused by 

 the quantities of loose ash thrown across the stream during 

 the secondary outbursts, but the most destructive, with the 

 exception of the one overwhelming the Guerin factory, have 

 been due to the saturation by rain of the accumulations of dust 

 on the inner and outer slopes of the crater rim, producing fluid 

 masses which have rundown the slopes of the mountain and the 

 radial gorges with the destructiveness of avalanches. 



The electrical displays in connection with each of the great 

 outbursts were on the grandest possible scale. Such displays 

 characterised the eruption of La Soufriere in 18 12 according to 

 contemporary reports. 



NO. 1733, VOL. 67] 



