44 



THE BUlLUlNf; OF AN' ISLAND. 



CHAPTER V. 



Arrangement of the "Blue-beach" Rocks. 



After having accumulated a good many observations in regard to the dip 

 of the blue-beach set of rocks, one of the first things we discover is that the 

 varied dips admit of being grouped into two great classes, namely, in the first 

 place, the dips which look to some point in the southern quadrant that is to 

 say, they are all included between southeast and southwest, and, in the second 

 place, the dips which look to some point in the northeast quadrant that is to 

 say, thev are all included between north and east. The accompanying diagram 

 makes this distinction clear at a glance. The dips of the blue-beach rocks but 

 very rarely pass beyond the limits here indicated for each class, and in continu- 

 ing our studies vve soon discover the great value of this classification. We 

 soon find that one or other of these two sets of dips extends itself continuously 

 over a considerable section of the island and becomes characteristic of that 

 section, while by-and-by we are furthermore able to make out the boundaries 

 between the various sections, and finally reach definite and most instructive 

 conclusions. 



Fk;. i6. 



Arrangement of the Rocks in the Western Oblong. 



In commencing our observations for ascertaining the arrangement of the 

 rocks of the blue-beach formation it is most convenient to begin with the 

 Western Oblong, where the points above mentioned are illustrated in a clear 

 way and on a large scale. The highly inclined strata whose edges cross the 

 high-road to Frederiksted, and may be seen for a considerable part of the way 

 between the works at Lower Concordia and those at Wheel of Fortune, have 

 already been mentioned, and it was also pointed out in what an interesting wav 

 the presence of these strata is revealed, even where their edges are covered by 

 road material or by soil and vegetation. 



