l l J4 CUBA AND PORTO RICO 



the elevation of the island above the sea. Some of these 

 are beautifully shown on the east side of Montego Bay, 

 where six distinct levels, or benches, separated by deep 

 slopes, rise above one another in stair-like arrangement. 

 At no other single locality are so many of these shown 

 in such close juxtaposition, but one or more of them can 

 be individually distinguished at many localities around the 

 island, some of them being as high as two thousand feet. 

 At a single glance these terraces in Jamaica do not present 

 the perfection of the allied phenomena exhibited on the 

 southeast coast of Cuba, but, nevertheless, they record a 

 similar geologic history. 



Naturally the integrity of these benches varies with 

 their relative age and altitude. The higher ones are more 

 fragmentary, because degradational processes have longer 

 been working upon them. Fragments of the lower 

 benches are better preserved, although much broken by 

 erosion, while none is as perfect in contour as are the 

 benches of the coastal plain. All have been cut across by 

 rivers, etched and dissolved by rainfall, and undermined 

 by encroachment of the waves ; but they are, nevertheless, 

 remarkable features. 



A narrow strip of low coast plain occurs here and there 

 interruptedly around the island, between the sea and the 

 back-coast border. In some places this is an old beach 

 only a few feet wide; in others it has greater width, and 

 indents the back-coast border for miles. These patches 

 of coastal strip are either elevated reef rock, like the 

 seborucco of Cuba, marginal stretches of white sea-sand, 

 or land- derived alluvium ; and they present minor features 

 of relief. 



The coastal plains and slopes covered with alluvium 

 are often extensive areas, especially on the south side of 

 the island. The largest of these is the plain of Liguanea, 

 upon which Kingston is situated. This plain is over 

 twenty-five miles in length, and its width, which averages 

 six miles, is greatest near its western end, in the district 



