The whole of the land that has hitherto been cultivated in the province of British Guiana, and many millions of acres in addition, have been gained from the sea since the boundaries of the Atlantic Ocean were originally fixed. The accumulation of earthy particles and vegetable matter that form this land, is nearly 150 feet deep, close to the shore. At highwater, and especially during spring-tides, the sea still rises several feet above the ordinary level of the land, and would certainly overflow it to an extent of many miles, if it were not prevented by artificial embankments; we may therefore form some idea of the extent of the deposit; but it would be folly to offer any conjecture as to the ages that may have elapsed since the commencement of its formation.

The three great rivers which have given their names to the several colonies of the province, derive their chief sources from that chain of mountains which rises under the equator, near the mouth of the Amazon, in longitude 50°, and extends to the west, with an inclination northerly, to about 66° west of Greenwich, and which may be called the Lesser Cordilleras, as the Andes are the Greater. But as it is now certain that the River Essequibo has a communication with the Oronoko, and that the Oronoko communicates by the Rio Negro with the Amazon, it is no great stretch of the imagination to suppose, that part of the soil that forms the islands in the Essequibo, and which is considered the most fertile in the colony, may have been brought from a far greater distance.