THE BUILDING OF AN ISLAND. 



n 



three small hills, thus giving rise to the pieturesque appearance so greatly 

 admired by visitors to the island. Many residents must have noticed the great 

 blocks of rock that lie about the uppermost parts and back slopes of the 

 middle and eastern hills, as well as the fourth hill, still farther east, on which 

 "Blue Beard's Castle" stands. It is obvious that these blocks are from the 

 broken edges of a thick and hard stratum coming up at a moderate angle from 

 the south. The somewhat softer rocks below this bed have been cut away 

 where they crop out beyond it towards the north, so that a slight hollow has 

 been made there in each case, most marked behind the easternmost hill, where 

 it is occupied by the street known as " Polyberg." 



If we add to the above observations one from Professor Cleve's account 

 of St. Thomas, we are introduced to a repetition of the northern of the two 

 above named dips. The Professor writes of the blue-beach rock: "In the 

 harbour near the fort and on the small cay of Prince Ricpert the rock forms 

 regular strata of half a meter (nearly 20 inches) in thickness. Their strike is 

 S.S.E. N.N.W. and dip 30 degrees to E.N.E." Putting this observation 

 with those described above, we may illustrate the probable positions of the 

 strata in a rough way by the accompanying diagram (Fig. 27), in regard to 



Fig. 27. 



which it will, of course, be understood that only the position of the anticlinal 

 axis to the back of the town can be given with any approach to accuracy ; the 

 synclinal axis must come somewhere between the town and Prince Rupert 

 rocks, but cannot be more closely indicated, at all events not without fuller 



investigation. 



It seems then pretty clear that the ancient elevation of the rocky masses 

 in St. Thomas has been brought about by the same force as has raised the 

 ridges of the older rocks in St. Croix, and the possibility at once presents itself 

 that the force is the same as has at first pushed up the whole great east and 

 west axis. 



There was, no doubt, a recent lifting of St. Thomas at the same time as 

 the corresponding lifting of St. Croix, that is to say, after the deposition of 

 the limestones ; but as St. Thomas lacks these limestones, we can only judge 

 of the direction of the force from the form of the island, and the line of its 

 length would seem to justify the belief that the recent force of elevation has 



