24 bulletin: museum of comparative zoology. 



the Central Mountains. The highest sumnoits of the plateau are found 

 in the crests surrounding the Clarendon basin, near the centre of the 

 island, which attain a maximum altitude of about 3,000 feet or less than 

 one half that of the highest Blue Mountain peaks. The highest of the 

 plateau remnants is Mount Diablo, which forms the divide between the 

 two coasts as well as between St. Thomas and Clarendon valleys. It is 

 reported to be 3,053 feet in altitude. Altitudes exceeding 2,000 feet 

 continue southward from the west end of the Clarendon Yallej almost 

 to the southern coast of Manchester and St. Elizabeth. Some of these 

 are given by the official surveys as follows : Mocha, 2,558 feet; Cabbage 

 Hall, 2,983 feet; Drayton, 2,210 feet; Sedburg, 2,269 feet; Mason's 

 Run, 3,000 feet; Craig Head, 2,619 feet; Aboukir, 2,019 feet; and 

 "Water Mount, 1,844 feet. Don Figuera Mountains, over 2,400 feet, 

 Mile Gully Mountains, 2,514 feet, and Carpenter's ]\Iountain of Man- 

 chester, 2,400 feet, are also remnants of this old plateau level, near the 

 south coast of the central region. On the east the John Crow Ridge 

 (alt. 2,110 feet), an elongated summit extending parallel to the coast, may 

 be either a remnant of the old summit level or the oldest and highest of 

 the base level plains cut out of its marginal topography. On the south 

 side of the Blue Mountain Ridge the highest summit of Yallahs Mountain 

 (alt. 2,254 feet) is the sole surviving remnant of the old summit topog- 

 raphy of that side of the island. These elevations indicate that the 

 region of maximum altitude of the plateau was in the widest part of the 

 island from near the south coast of Manchester to and just across the 

 boundary of St. Ann. 



In places along the south coast there are isolated white limestone 

 remnants of the plateau, which are separated from the main body by 

 the wide indentations of the lower lying Coastal Plains. The Port 

 Henderson and Healthshire Hills of St. Catherine, and the Braziletto 

 Mountains and Portland Ridge of Clarendon, are of this type. 



Tiie materials of the plateau and its outliers are soluble limestones, — 

 old sheets of calcareous oceanic sediments now chalky or subcrystalline 

 in texture, which were deposited upon and around the bases of the Cen- 

 tral Mountains and attained their present altitude by a subsequent ele- 

 vation. These white limestones are described elsewhere in this paper 

 under the names of the Montpelier, I\Ioncague, and Cobre formations. 

 The details of the configuration are largely due to the peculiar solvent 

 character of the limestone. These hills, especially in the interior, owe 

 their configuration largely to the agency of solution, while the forms of 

 the Central Mountains are due entirely to denudation. So important 



