218 Mil. JUKES-BROWNE AND PllOF. IIAREIBON 



and is from 15 to 20 feet high ; it rests on white Eadiolarian earth, 

 and its basal bed is a very soft earthy limestone or marl like a friable 

 chalk. This is about 6 feet thick, and appears to be a true coral- 

 mud ; an analysis of it is given on p. 224, and its minute structure 

 is described by Mr. Hill (p. 247). This marl passes upwards into 

 a soft marly rock containing many broken pieces of coral, and this 

 in turn gradually changes upwards into a hard limestone. At 

 Codrington College, about 20 yards below the garden, there is only 

 a few inches of coral mud and sand below the coral-rock, and here 

 it rests on a soft yellowish ibraminiferal marl belonging to the 

 Oceanic Series. 



(d) The great Escarpment. — In the north-eastern part of the 

 island the raised reefs are cut off by erosion, and the line of their 

 intersection forms an abrupt escarpment, which is in some places a 

 line of clifis. This escarpment describes an irregular sigmoid curve 

 rouud the Scotland District, commencing near St. Mark's Church in 

 St. John's parish, where for a short distance it forms a little cliff 

 facing west; thence it curves round by Sealy Hall, and passes 

 northward to Codrington College, where the base of the coral-rock is 

 about 300 feet above the sea, facing north-east, and running at the 

 foot of a steep slope which terminates upward in a plateau at a level 

 of about 570 feet. Thence both the base and the summit-levels 

 rise steadily to the north-west, while the upper part of the steep 

 slope passes into a vertical cliff. 



The finest part of this escarpment lies between St. John's Church 

 (800 feet) and Castle Grant (107^^ feet) and includes the range of 

 Hackleston's Cliffs ; here there is a vertical face of from GO to 70 feet 

 of coral-rock, rising from a slope of broken and tumbled masses of 

 the same rock. Most of the cliff-face is covered with small shrubs, 

 ferns, and climbing plants, and much of the slope below is hidden 

 by i)alms, trees, and underwood, so that when viewed from the 

 railway it looks like a wall of foliage. 



At Castle Grant and Little Island the fallen masses of rock are in 

 some places banked to within 20 or 30 feet of the summit, but at 

 other parts there is a vertical face of 50 or 00 feet in dej^th. The 

 surface of the rock is very rough, being fretted and honeycombed by 

 the action of the rain, and in some places coated with sheets of 

 travertine derived from the solution of its upper portions. Perns, 

 llianas, and rock-plants of many kinds grow on these cliffs wherever 

 they can find loothold, and add to the picturesqueness of their 

 aspect. Great cracks and clefts occur in many places, and occasion- 

 ally after heavy rains a huge slice is detached and falls with an 

 avalanche of stones to the bottom. 



On the west part of Castle-Grant estate this bold line of cliff ends 

 in a somewhat abrupt manner; the thickness of the coral-rock rapidly 

 diminishes westwards against the slope of the older rocks, which 

 finally emerge from beneath the coral and form a distinct ridge 

 running northwards to Chimborazo at an elevation of between 1000 

 and 1100 feet. On the west side of this ridge, and separated from it 

 by the valley of a little watercourse, there is a narrow slope of 

 Eadiolarian earth, crowned by a miniature escarpment of coral-rock 



