Why does not the great forest of the Oroonoco extend to the north, or the left bank of that river?
Why does it not fill that vast space that reaches as far as the Cordillera of the coast, and which is fertilised by various rivers?
This question is connected with all that relates to the history of our planet.

If, indulging in geological reveries, we suppose that the Steppes of America and the desert of Sahara have been stripped of their vegetation by an irruption of the ocean, or that they formed the bottom of an inland lake'-- (the Sahara, as is now well known, is the quite recently elevated bed of a great sea continuous with the Atlantic)--'we may conceive that thousands of years have not sufficed for the trees and shrubs to advance toward the centre from the borders of the forests, from the skirts of the plains either naked or covered with turf, and darken so vast a space with their shade.

It is more difficult to explain the origin of bare savannas enclosed in forests, than to recognise the causes which maintain forests and savannas within their ancient limits like continents and seas.' With these words in my mind, I could not but look on the Savanna of Aripo as one of the last-made bits of dry land in Trinidad, still unfurnished with the common vegetation of the island.

The two invading armies of tropical plants--one advancing from the north, off the now almost destroyed land which connected Trinidad and the Cordillera with the Antilles; the other from the south-west, off the utterly destroyed land which connected Trinidad with Guiana--met, as I fancy, ages since, on the opposite banks of a mighty river, or estuary, by which the Orinoco entered the ocean along the foot of the northern mountains.

As that river-bed rose and became dry land, the two Floras crossed and intermingled.