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



15 



Islands, of which they probably are the continuation, but I have not found any fossils in 

 them. To judge from their petrographical resemblance to the rocks of the Virgin Islands, 

 one may find it very probable that they are of the cretaceous age. By a careful explo- 

 ration of the island there is also a great probability of finding an eocene formation. The 

 very slightly disturbed appearance of the miocene limestone strata and the strongly meta- 

 morphosed rocks below them evidently prove that the cretaceous rocks were bent and me- 

 tainorphosed before the miocene time, which has been here, as in most other parts of the 

 West-Indies, a long period of calm, undisturbed by volcanic eruptions. 



In the capital I have seen a fine collection of specimens of minerals from the is- 

 land, the property of Don Pedro Resano, a distinguished mineralogisk Among them were 

 gold, mercury, silicates and carbonates of copper, etc, which proves that a geological survey 

 of the island probably would discover many treasures in the high moutains of the interiör. 

 I sincerely regret that I could not find time to visit Sierra Luquillo as I intended, where 

 probably much would be found possessing considerable geological interest. 



Quebradillas Arecibo. 



S:n Juan . 



Aguadillas. 



Receut formation (Alluvium aud shell-sand). 



Miocene limestone. 



Unfossiliferous rocks (Bluebeache, Felsite etc. probably cretaceous.) 



III. S:te Croix*) or S:ta Cruz. 



This island situated at 17°, 44' 32" Lat., and 64° 41' Long. (at the capital), has an 

 elongated outline, extending from E. to W. 36 kilom., and is 10 kil. in breadth. The 

 northern part of the island is traversed from east to west by a mountain-ridge, of which 

 the highest peaks Mount Eagle (350 met.) and Blue Mountain (332 met.) are situated be- 

 tween the north-western corner and the town of Christianstced. East of Christianstsed the 

 ridge is not so high, but has still peaks of 183 — 260 meters. The south-western part of 

 the island is a flat, slightly undulating and well cultivated level country. The shores 

 around the island are surrounded by large coral-reefs except on the north-western coast, 

 where the bottom, quite near the shore, is first reached at a depth two thousand metres 



*) A description of its geology was given in 1839 by S. Hovey Sillim, Am. Journ. Vol. XXXV p. 64. 



