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What must strike anyone flying over the country is the large number of arterial rivers and the complicated pattern of tributaries and branch streams, which make it appear that Guiana is truly a 'land of waters' and that no smallest part of the Colony is not served by a river of some kind. In fact the existence of rivers has always meant that there was a rough and difficult means of access to certain areas of the Colony. But only a few of the rivers are navigable, even to small boats, beyond a comparatively short distance, and what little development of the Interior there has been has always been governed by the degree to which the rivers were navigable.

In all the rivers there is no difficulty up to the points affected by the tide from the coast, but beyond these points travel is impeded by rapids and cataracts. A stretch of the Mazaruni, for instance, is more or less impassable for 120 miles almost immediately after the tide ceases to be effective. The largest of the falls is the celebrated Kaieteur, on the Potaro, which has a width in the rainy reason of 400 feet and a perpendicular drop of 741 feet. The Potaro descends 81 feet in three miles below the fall, by a series of very large cataracts. There has been talk for some years of harnessing the power of this superb fall, and if this is ever done it seems likely that the gorge through which the Potaro runs after its fall at Kaieteur will be dammed, so that the level of water in the gorge will be greatly increased; the power of this flow of water would be harnessed at the point where the Potaro emerges from the gorge. This would leave the extraordinary beauty of Kaieteur itself undisturbed.

The Essequibo, the largest river of the Colony, is navigable by large vessels as far as Bartica, and by boats for eighteen miles above Bartica. At this point there are rapids, and its course for much of the rest of its way is broken by falls and rapids. This difficulty has never completely dissuaded travellers into the Interior; at each fall the boats are unloaded and the goods carried to a point above the fall. The boats themselves are manhandled over the rapids, usually by a team of men hauling by rope. This operation is known to the river-men as a 'potash'a word derived from the French pronunciation of portage.

The Mazaruni has perhaps the most unusual course of all the Colony's rivers. It rises in the Merume Mountains in the area towards the point where the boundaries of Brazil, Vene

zuela and British Guiana meet. At its source it is 2,400 feet above sea-level. It flows south for some distance and turns first west and then north and produces its first large fall, the Peaima Fall. Then it suddenly turns south-east and approaches to within twenty miles of its own source, having described a rough oval. Soon it turns north-east and flows through comparatively level country to join the Essequibo at Bartica. It is on the first part of this north-eastern course that it passes through the diamond area. For most of its last stretch before joining the Essequibo it is a mass of fragmented islands at the heart of which is a complex of some fifty falls and rapids, some flowing parallel, others consecutive, to each other. To avoid this stretch of river a road had to be built from Bartica to Issano, on the Mazaruni at a point a few miles above where the fragmentation ends.

The Cuyuni rises in Venezuelan territory and for some of its way forms the boundary between Venezuela and the Colony. It flows to the east as far as the Tinamu Cataract and then turns south-east to join the Mazaruni a few miles above Bartica.

The Berbice is divided into two channels by Crab Island, the width there being about three miles from bank to bank. Even so its course through sand and clay belts means that no rapids are formed for many miles, and the Berbice is the most navigable of all the rivers. The steamer terminus is a short distance from the mouth of the Ituni, which is over one hundred miles from the mouth. During the rainy season, when high water means a freer passage for craft, the Berbice can be navigated by small boats as far as the rapids of Marlissa—which is the foot of the influence of the tides.

The Demerara is probably the best-known river in the Colony, and is commercially the most important. But compared with the Essequibo or the Berbice it is a small river. Its importance comes from the fact that its bar lies deeper than that of any of the other rivers of the Colony which flow into the sea, thus allowing the entry of larger vessels—although ships of greater draught than eighteen feet cannot pass the bar. It was for this comparative advantage that Georgetown was sited on the east bank at the mouth of the Demerara. The river rises in a mountainous offshoot of the Pakaraimas, and flows northwards roughly between the Essequibo and the Berbice. It is

navigable to steamers for eighty miles, and beyond this for small craft for another twenty-four miles, until the Malali rapids are reached, where, again, the influence of the tides ends. Above these rapids it is navigable again for fairly long stretches between rapids.

Most of the smaller rivers of the Colony, like the Pomeroon, Mahaica, Mahaicony and the Abary flow through the low-lying alluvial and clay and sand belts. They are navigable almost up to their sources and for the last fifty years or more they have proved useful as a means of transport to the various settlers who have taken up grants of Crown land on the riverain lands.

The other most prominent geographical feature of the Colony which strikes one when flying over it is the great central mass of flat-topped mountains-the Pakaraima chain, occupying most of the western portion of the Interior, and stretching southwards from the Cuyuni and eastwards to the Essequibo between the Potaro and Rupununi rivers. Most of this system is composed of series after series of terraces and broad plateaux, with frequent perpendicular sandstone escarpments, which gradually rise to form a large, undulating tableland about 3,500 feet above sea-level. At their climax these series reach the great plateau mountain of Roraima, which is a little over 9,000 feet. Its plateau of twelve square miles surrounded by a once apparently unscaleable escarpment inspired Conan Doyle to write The Lost World. It is a unique physical area, and from certain points it is possible to be surrounded by horizons containing these bold, flat-topped mountains of sandstone. It has been suggested that they once were cliff-faced islands in some ancient sea which then engulfed the land. Mount Roraima is the point where the boundaries of Venezuela, Brazil and British Guiana actually meet, and a stone stands on its summit, placed there by the International Commission in 1931.

The Pakaraimas are partly covered with forest, more especially in the valleys, but the plateaux formed by the range are usually savannas. The flat tops of the mountains themselves are expanses of dark, uneven rock with small areas of stunted vegetation not unlike miniature trees. Botanically these mountains, especially Roraima itself, are remarkable, possessing flowers of great rarity and often great beauty. On the escarpment and summit of Roraima, Rapatea, rare heathers, Sarra


cenia—a beautiful if rapacious pitcher plant-and the graceful bell-shaped Campanula can be found with no difficulty.

The Kanuku range divides the north and south Rupununi savannas. None of its peaks is more than 2,000 feet. The range begins at the Takatu river and continues eastward towards the Essequibo, being pierced halfway by the Rupununi river. The Kanukus are entirely covered with forest, and have not been completely explored. It is thought that the mineral possibilities may one day prove to be worth exploiting. It is an area rich in balata, a wild gum gathered by the Amerindians and used for golf-ball casings and the cases of marine cables. The value of true balata has decreased in recent years owing to the discovery of an adequate ersatz.

The savannas of British Guiana deserve a special geographical mention at this point. Apart from the large Rupununi savannas already mentioned and the small savanna areas formed by the Pakaraimas, there are the so-called Intermediate Savannas lying immediately behind the north-eastern coastlands in the Berbice District, and the Ituni savannas lying some sixty miles from the bauxite town of Mackenzie. During the last few years the Rupununi has received special attention from the Government, and experiments go on to improve the conditions for cattle-raising there. More recently a research station has been set up in the Intermediate Savannas also to look into the possibility of cattle-raising in an area much easier of access from the Coast. Mineral deficiency in the grass is the trouble with both the Rupununi and the Intermediate Savannas as cattle areas. The Ituni Savanna has grass of even worse quality and no attempt has been made to raise cattle here. It is entirely unoccupied, but the bauxite company at Mackenzie, which is always exploring the possibilities of further deposits, has thrown down a jeep trail into the savannas and is looking for bauxite in this area.

Geologists describe the Interior of British Guiana as one of the most 'stable areas' of the earth's surface. During hundreds of thousands of years the surface of the land has been slowly rising, and it is this gradual rise that has produced the rapids at the termination of the force of the tides. Except for the estuary of the Essequibo one is struck by the comparative narrowness of the rivers. This is because the rivers now flow

only along the deeper parts of the valleys and waterways which were originally eroded by much larger rivers. The rise in the land has brought about changes in contour which, in their turn, have altered the main lines of drainage. The river system has thus played a smaller part than one would have supposed in the formation of the alluvial coastlands, with their sands and clays and large areas of pegasse, a peat-like soil which I will describe more fully later. In his Principles of Geology Sir Charles Lyell says that these deposits have been laid not so much by the Guiana rivers themselves as by currents from the mouth of the Amazon.

The geology of the Colony in general is complicated, and I have thought it better to give here only a very general indication of the geological structure. I would refer readers who are particularly interested in this subject to Sir John Harrison's Geology of the Gold Fields of British Guiana (1908) which contains a general description that has never been superseded.

Since the days of El Dorado the Colony's mineral resources have been a source of hope and endeavour. Later in this section I describe various mining activities in some detail, but the following is a list of the important mineral resources of the Colony.

Bauxite (see pp. 177–83) is produced in the Mackenzie area, sixty miles up the Demerara, and at Kwakwani on the Berbice. Bauxite forms 90 per cent of the value of the Colony's entire mineral production.

Gold (see pp. 183–5) is found in the alluvial deposits of much of the northern part of the Colony, and in a few areas in the south. In the past it has been mined, particularly in the NorthWestern District, on a large scale by individual prospectors, but the alluvial deposits are nearly worked out and large-scale operations with dredgers have become necessary-as at Tumatumari, headquarters of British Guiana Goldfields Consolidated, a concern supported by the Colonial Development Corporation.

Manganese of low grade occurs at a number of points in the North-West, but at Matthews' Ridge, between the Barima and the Barama, a large deposit of good ore has been found and will eventually be worked on a large scale.

Diamonds are produced entirely from small workings,

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