JAMAICA 191 



By tacit consent, the innumerable eminences of the 

 plateau are called hills in Jamaica, to distinguish them 

 from the central mountains. The higher summits of the 

 plateau are found near the center of the island, one 

 of which, Mount Diablo, is reported to be 3053 feet in 

 altitude. 



The materials of the plateau and its outliers are soluble 

 white limestones like those of Cuba sheets of old cal- 

 careous oceanic sediments, now hardened into subcrys- 

 talline texture, which weather into ragged honeycombed 

 surfaces or dissolve away under the tropical rainfall into 

 a unique configuration of roughly serrated hills, basins, 

 and deep drainage-ways leading to the sea. Some of the 

 basins are called cockpits wonderful funnel-shaped sink- 

 holes, often live hundred feet or more in depth, with steep 

 acclivities ascending into pointed conical hills no less 

 a i mular than the pits. Then there are great basin-shaped 

 valleys, themselves an evolution of the cockpits, consist- 

 ing of deep holes with wide, flat bottoms, in which the 

 plantations are situated, inclosed by rugged limestone 

 walls which rise from twelve to twenty-five hundred feet 

 above them (the height varying in different localities) and 

 separate the valleys by wild and uninhabited uplands. 

 These valleys differ from one another chiefly in area. In 

 many cases, although well watered, they have no outlet, 

 while in others the barriers have been partially eroded, 

 and they are drained by rivers leading to the sea. 



The largest and most populous of these depressions are 

 those of St.-Thomas-in-the-Vale, the great Vale of Claren- 

 don surrounding the Clarendon Mountains, the Hector 

 River basin in northern Manchester, and the Niagara 

 River Valley along the boundary of St. Elizabeth and St. 

 James. Montpelier Valley, along Grea1 River in Han- 

 over, and Morgan's Out Valley in Westmoreland, are 

 similar basins which have had drainage-gaps cut through 

 their surrounding barriers. The latter now constitutes an 

 interior enibayment of the great plain of Savana-la-Mar. 



