238 The National Geographic Magazine 



in all directions to the sea, except to- 

 ward the south, where its constructional 

 slopes meet those of Carbet and form 

 a neck of land. This general plan is 

 modified, however, by bold strokes of 

 nature's erosive carving, whereby the 

 surface is cut into numerous radial di- 

 vides and canyons. 



The crest is a steeper hill surmount- 

 ing larger piles composed of pumice. 

 The top was a truncated loaf, in the 

 summit of which is a bowl-shaped basin, 

 the floor of the old caldera, which has 

 existed since prehistoric time. Around 

 this rim bowl was a circle of pointed 

 hills, of which Morne La Croix, the 

 highest, stood about 200 feet above the 

 caldera floorupon its southwestern edge. 

 In the floor of the caldera was a lake 

 called L'Etang de Palmistes. It meas- 

 ured 150 meters in circumference, and 

 varied in volume. This floor of the 

 caldera was covered with pumiceous 

 soil, beneath which were mud and 

 boulders of pumice-stone. 



The perimeter of Pelee where it meets 

 the sea, except from the southern edge 

 of St Pierre to the mouth of the Riviere 

 Blanche to the northward, is everywhere 

 bordered by steep bluffs, as if it had 

 been encircled by a trimming knife. 

 The ten rivers which were their branch- 

 ing headwaters, originating almost at 

 the summit, diverged toward the sea 

 and cut the sloping surface into numer- 

 ous triangular segments. 



The surface of one of these segments 

 lying toward St Pierre is relatively of 

 lower altitude than those which sur- 

 round it, and does not bluff upon the 

 sea as the others do, although it is bor- 

 dered by steep cliffs on the north and 

 south of the Rivieres Blanche and 

 Mouillage respectively. The surface 

 of this lower-lying segment between the 

 opposing cliffs is in turn etched of sev- 

 eral other streams and presents within 

 itself a varied topography. 



The boundary cliffs run nearly from 

 the summit nearly to the sea, where 



they suddenly diverge at right angles, 

 parallel to it, leaving little strips of 

 beach between. This cliff-bound area 

 is a great natural amphitheater. Upon 

 one of these narrow lateral beaches at 

 the south end the principal part of the 

 town of St Pierre was built. In other 

 words, St Pierre lay within the southern 

 edge of the natural amphitheater, sur- 

 rounded by steep cliffs and closely built 

 against one of the latter. This is an 

 important fact, which, should the ex- 

 plosive theory prove true, would explain 

 much of the damage which has been 

 wrought. 



GEOLOGY OF MARTINIQUE* 



Nowhere in the rocks of Martinique 

 has there been discovered an}' evidence 

 of sedimentary rocks derived from a pre- 

 existing land, such as are found in Bar- 

 bados and the Great Antilles, and this 

 fact, which is also apparent in the 

 other volcanic Caribbees, strongly up- 

 holds the conclusion that these islands 

 were built up from the sea bottom solely 

 through the agency of piled-up volcanic 

 ejecta. 



The Island of Martinique is composed 

 almost entirely of volcanic material. 

 In addition to the volcanic rocks, there 

 are two other types of formations which 

 throw a great deal of light upon its 

 geological history. These are, first, ele- 

 vated estuary deposits of alluvial ma- 

 terial at the mouths of its rivers on the 

 west coast, and deposits of calcareous 

 oceanic sediment resting upon a base- 

 ment of older volcanic rocks eroding the 

 east coast. 



Along the southeast coast are some 

 calcareous benches composed of material 

 similar to that now forming off that 

 shore, which have been elevated above 

 the sea by epeirogenic movements. The 



* The geology of Martinique has been pub- 

 lished in detail by Moreau de Jonnes in 1814 ; 

 Ch. Sainte-Claire-Deville in 1843. Recently 

 Octave Hayot, of Martinique, published an 

 essay on the subject. 



