16 bulletin: museum of comparative zoology. 



feebler amplitudes only are indicated in the perizonal continental 

 borders. 



The extreme length of the island is 144 miles, its greatest width is 

 49 miles, and its least width is 21^ miles, from Kingston to Annatto 

 Bay. The longest axis lies in east and west directions. The outline 

 of the island which encloses 4,207^ square miles,* about one eleventh 

 the area of Cuba and 500 square miles greater than Porto Eico, is an 

 elongated parallelogram whose corners have been obliquely truncated, 

 resultinij in a wide oblonor central area from whose east and west ends 

 project two broad peninsulas. 



At first glance, the outline does not appear to have any peculiar 

 meaning, but when analyzed in connection with the geologic structure 

 and adjacent submarine topography, it is of great significance. An in- 

 teresting feature of this outline is that, while the major trend of the 

 north coast and the island as a whole is east and west, nearly one half 

 the coast line is diagonal to this cardinal direction. The northwest and 

 southeast trends are survivals of the earlier days of Antillean history. 

 The predominant east and west directions are produced by a later 

 geographic revolution. 



Configuration. — The relief of Jamaica is dominantly mountainous, 

 for the interrupted Coastal Plain constitutes only a narrow fringe around 

 the island. The first distant view from the east skows a group of 

 mountain summits rising above the expanse of sea in a tangled mass, 

 apparently without systematic ridges or secondary types of relief fea- 

 tures by which its configuration can be classified. The higher summits 

 of this end are usually, if not alwaj's, veiled in clouds, so that only the 

 lower half of their slopes is ordinarily visible. The mists are appar- 

 ently forever present in tiie upper regions. As the coast is more closely 

 approached and the island encircled, the configuration resolves itself 

 into differentiated forms, pi'esenting four distinct and easily recognizable 

 major types and numerous secondary modifications, which will now be 

 explained. Its chief features are : (1) the interior mountain ranges 

 constituting the nucleus of the island ; (2) an elevated limestone 

 plateau which surrounds the interior mountains, and ends abruptly 

 towards the sea; (3) tljo coastal bluffs or back coast border of the sea- 

 ward margin of the plateau ; and (4) a series of low, flat coastal plains 

 around the periphery of the island between the sea and the back coast 

 border. The relation of these features is shown in the various profiles 

 and sections. 



* As given by the Jamaican Land Department. 



