384 MEXICO, CENTEAL AMERICA, WEST INDIES. 



The southern extremity of the island terminates in the Portland Ridge pro- 

 montory, a crest of slight elevation now connected by a dejDression with the main- 

 land, but at one time forming a distinct island. The western extremity of Jamaica 

 also terminates in a bold promontory 3,500 feet high, which has been named the 

 ** Dolphin's Head," from a fancied resemblance to that cetacean. The whole mass 

 of which it forms the extreme point is almost completely separated from the rest of 

 the island by the depression through which flows the Great River. 



Although, like the other large West Indian islands, Jamaica has no active 

 volcanoes, old eruptive matter occurs near Spanish Town on the south side, and 

 earthquakes are by no means rare. Towards the end of August, 1883, prolonged 

 rumbKngs, like the sound of distant thunder, were heard in the Caj^man Islands. 

 It has been suggested that these sounds, which caused great alarm amongst the 

 natives, were an echo of the terrific eruption of Krakatau, propagated across the 

 globe from the Sunda Archipelago to the Antilles. 



For a distance of about 60 miles east of the Great River the northern slopes of 

 the hills are formed of calcareous rocks analogous to coralline reefs and pierced by 

 countless caverns and cavities through which the running waters escape. In many 

 places the surface of the rocks remains dry at all seasons, however copious be the 

 rains. This part of Jamaica is like Yucatan, but the resemblance is still greater 

 to Carniola, owing to the rugged character of the land. There are few regions of 

 the globe more rich in underground reservoirs and streams which again well up 

 to the surface all round the verge of the limestone district. Here and there the 

 subterranean rivers and their branches may be traced by the springs and fountains 

 in the caves occurring at intervals along their course. The slope of the hidden 

 watershed is often different from that of the surface. Lakes also are formed 

 either on the surface or in underground cavities above the rocky sills. 



Rivers. 



The Black River, which reaches the sea on the south-west coast, comprises in 

 its basin a large number of underground feeders. It is also the only river in the 

 island that is navigable for 30 miles by flat-bottomed craft. None of the others 

 are navigable at all, not even the Dry (Minho), or the Cobre, which are the two 

 largest. Both water the southern slope of the island, which is the most extensive, 

 but which receives the least quantity of rain, not being exposed to the moist trade 

 winds. During the floods the Cobre has occasionally a discharge of 80,000 cubic 

 feet per second, but its normal volume is only about 360, and at low water not more 

 than 100 cubic feet. Like the north-western streams, the Cobre has its underground 

 system of drainage. 



Climate, Flora, FaUiNA. 



The climate o- Jamaica resembles that of Cuba, presenting the same contrasts 

 between the northern and southern seaboard, between mountains and plains, 

 between the leeward and windward quarters. Although somewhat sheltered 

 from the moist rains by Cuba and San Domingo, it lies fully in the track both of 



