ON THE GEOLOGY OF THE NORTH-EASTERN WEST-INDIA ISLANDS. 



23 



coast the seacliffs are also composed of the same kind of stratified, metamorphic silicious 

 liinestones, but near the sea they are covered by a more recent formation of white gra- 

 nular limestone, in which I could find no fossils, so that the age of that rock is unknown. 

 In some places occur large masses of modern formations, detrital fragments of older rocks 

 carried down by rains or rivulets, and along the shores recent calcarious sand. The Dutch 

 town of Philipsburg is built upon a flat land covered by such modern deposits. The 

 hills west of the town consist chiefly of igneo-sedimentary rocks, old tufas and breccias 

 greatly resembling the rocks of S:t Bartholomew. Among the detritus at the foot of the 

 hills I have seen loose blocks of syenite-porphyry of the same kind as that rock in S:t 

 Bartholomew. I have seen nowhere in these mountains the same kind of gray limestone, 

 which occurs so plentifully in S:t Bartholomew, but I have no doubt that it may be found, 

 as near the French settlement I have met with some loose blocks of gray, härd and solid 

 limestone of the same petrographical character as the rock of S:t Bartholomew. 



The stratified beds of tufas and breccias in the hills west of Philipsburg strike N. E. 

 — S. W. and dip S. E. about 30° — 20°. On the southern coast, west of the same town, 

 the cliffs are composed of regular strata of metamorphic, silicious limestone, striking E — W 

 and dipping southwards 20° — 30°. These strata are often penetrated by dikes of green- 

 stone; they have a reddish colourand are interstratified with large beds of a black heavy 

 rock containing much manganese and constituting a kind of impure psilomelane. In cavi- 

 ties in the strata I have found a black crystalized mineral resembling Cronstedtite, epidote. 

 chalcedony, magnetic iron in octahedrons and specular iron. At Pelican Point the last 

 described strata are covered by beds of a härd, white limestone, withöut any other fossil 

 than some scarcely recognizable traces and casts of shells. This limestone has exactly the 

 same character as the surface-stratum of Anguilla, of which I suppose it may have been 

 the continuation. The stratum runs N. E. — S. W. and dips 15° to the N. W., and it is 

 incongruously imposed upon the elder 

 strata below. The western part of the 

 island around the French settlement of 

 Marigot is almost entirely covered by 

 recent shell-sand and detrital masses, ha- 

 ving only a few uncovered rocks of stra- 

 tified silicious limestone. I have not visi- 

 ted the northern part of the island, but 

 from the general configuration of that 



Recent formations (shells-and and detritus). 



Metamorphic (stratified) rocks (silicious lime- 

 stone.) 



Igneous or Igneo-sedimentery rocks (diorite, IKJJ+J 



tufas etc.) 

 White härd limestone (Miocene?) 



Map of S:t Martin. 



