How the outer islands of the Bocas had been formed, or were being formed, was clear enough.

But what about the inner islands?
Gaspar Grande, and Diego, and the Five Islands, and the peninsula--or island--of Punta Grande?
How were these isolated lumps of limestone hewn out into high points, with steep cliffs, not to the windward, but to the leeward?
What made the steep cliff at the south end of Punta Grande, on which a mangrove swamp now abuts?
No trade-surf, no current capable of doing that work, has disturbed the dull waters of the 'Golfo Triste,' as the Spaniards named the Gulf of Paria, since the land was of anything like its present shape.

And gradually we began to dream of a time when the Bocas did not exist; when the Spanish Main was joined to the northern mountains of the island by dry land, now submerged or eaten away by the trade-surf; when the northern currents of the Orinoco, instead of escaping through the Bocas as now, were turned eastward, past these very islands, and along the foot of the northern mountains, over what is now the great lowland of Trinidad, depositing those rich semi alluvial strata which have been since upheaved, and sawing down along the southern slope of the mountains those vast beds of shingle and quartz boulders which now form as it were a gigantic ancient sea-beach right across the island.

A dream it may be: but one which seemed reasonable enough to more than one in the boat, and which subsequent observations tended to verify..