Page:Transactions of the Geological Society, 1st series, vol. 3.djvu/246

 mile in breadth, and terminated by a cliff of coral rock, varying in elevation from twelve to more than twenty feet; sometimes indeed having a considerably greater height. Although these terraces are in general bounded by cliffs which run parallel to the line of the coast, yet they are not wholly uninterrupted, for here and there the high grounds advance towards the shore, and break their continuity for a short space, where the terraced form of the land is again taken up.

The rocky boundaries to each terrace are formed by broken pieces of madrepores of different species thrown about in great confusion, held together by a calcareous cement of greater or less hardness. Such are the madrepore with contiguous round cells, No. 1. and the meandritical madrepore bored by mytili, No. 2.

Near the garrison of St. Ann's, and to the eastward of it, the rocks bear the character of a dull compact chalky-looking limestone, with ramose Alcyonia, No. 3, while considerably to the westward, as in the parish of St. Peter's, the rock is more distinctly coralloidal: it contains also some natural caverns, from which very perfect organic remains may be procured.

In sinking a well at the Naval Hospital, a little to the north-east of St. Ann's, the following specimens were met with in the order in which they are enumerated, exhibiting in a striking manner the increasing compactness of the rock, in proportion to the pressure of the incumbent mass.

1. A madrepore with contiguous round cells.

2. A madrepore with detached round cells.

3. A hard porous mass with terebratulites and lenticular concretions, which are perhaps organic remains.

4. A limestone analogous to the preceding but much harder.

In no part of this district, including almost all the leeward or