18 BULLETIN: MUSEUM OF COMPARATIVE ZOÖLOGY. 
The origin of this configuration, which is inextricably associated with 
the stratigraphic history and geologie evolution of the island, will be 
more fully explained in the later chapters of this report. 
The main mass of the island is an elevated region of rugose relief, 
consisting of a nucleal mountain range surrounded by a high dissected 
plateau. The higher region does not slope gradually to the sea, but is 
terminated near the coast by very abruptly truncated bluffs, steep slopes 
or benches, usually, but not everywhere, separated from the sea by a 
narrow strip of plain, as if the original coast margins of the mountainous 
upland once extended much farther seaward and had been horizontally 
planed away by the sea's encroachment. The abrupt sea face of the 
mountainous upland is a marked topographic peculiarity, which we shall 
call the back coast border. This narrow ribbon of coastal plain is not a 
continuous belt, but is interrupted, and constitutes an important feature 
of the Jamaican topography. The secondary features are interior basins 
and valleys in the summit of the plateau, certain coastal benches and 
terraces carved out of the margin of the back coast border, and the 
drainage valleys. 
Of these the interior mountains and the limestone plateau are by far 
the most conspicuous features, and will be first discussed. 
The relation of the plateau region to the interior mountains is that of 
an elongated mesa or bench completely surrounding a higher sierra, tho 
plateau having an outline somewhat like a child's bib, through the neck 
of which the mountains of the east protrude, surrounded by a narrow 
collar of plateau, while the main expanse or apron, which lies towards 
the west, presents occasional views of the buried mountain structure, 
through rents and holes made by water. The two types of reliof of the 
upland regions are readily distinguishable, even from a great distance, 
by the entirely distinct physiognomy of their slopes. The interior moun- 
tains are marked by deeply etched knife-edged salients (cuchillas) and 
angular re-entrants which present the aspect of a crumpled handker- 
chief picked up by the middle, —an illustration used by Columbus in 
describing the mountains of the Indies to Queen Isabella. These pe- 
culiar escabradurate ! slopes are shown in the illustrations on Plate VI. 
The corrugations of the Blue Mountain Ridge are plainly visible from 
Kingston. On the other hand, the hills of the limestone plateau, 
whether of peaked or flattened summits, present uncorrugated, densely 
wooded slopes. 
1 From the Spanish Escabradura, signifying the erosion scratches, — “ Bad- 
land," relief of American usage. 
