THE GUIANA UPLANDS. 9 



also accounts for the differences that have arisen between the Governments of 

 Great Britain and Brazil regarding- the limits of their respective domains about 

 the sources of the Essequibo and E-io Branco affluents. The whole of the dividing 

 zone sometimes takes the name of the River Parira, a word of Macusi origin, 

 vv^hich, according to Schomburgk, indicates the geological constitution of the 

 land — a ferruginous conglomerate. Above the water-parting rises a column of 

 trap formation, which is regarded as a sacred object by the surrounding Macusi 

 Indians. 



A few other isolated groups follow southwards as far as the neighbourhood 

 of the sources of the Essequibo, which stand at an altitude of about 820 feet. 

 Here the heights, glimpses of which are at rare intervals obtained from the river 

 banks across the dense foliage of the primeval woodlands, do not develop a con- 

 tinuous amphitheatre of rounded hills, but form a number of distinct ridges 

 sharply defined by deep transverse gorges. They constitute so many " huge 

 blocks, some of which have a length of about 90 miles, standing on very low 

 pedestals of plateau formation."* 



According to Coudreau, the loftiest summit in this region is Coirrit, or 

 Cuirrid Dekeuou (Brown's Acarai), the " Mountain of the Moon," which lies 

 near the sources of the Takutu, and attains an altitude of about 5^000 feet. It 

 is the culminating peak of a ridge with a mean elevation of some 3,000 feet, 

 which sweeps round in a vast bend first to the south and then to the east, as far 

 as Mount Aourriawa, where rise the headwaters of the Essequibo. Farther on 

 are developed the Curucuri heights, seen from a distance by Coudreau. Here 

 the water-parting coincides exactly with the crest of the mountain range. On 

 one side descend the streams flowing to the Essequibo, on the other those 

 flowing to the Trombetas affluent of the Amazons. 



The sierra falls in the direction of the east, where it forms the natural 

 boundary between Dutch Guiana and Brazil. According to Brown, the highest 

 summits rise scarcely 300 feet above the sources of the River Corentyne, which 

 forms the frontier line between Dutch and British Guiana. 



The Tumuc-Humac Raxge. 



Farther on the system again rises, and here takes the name of the Tumuc- 

 Humac range, a term of unknown meaning. .From its northern slopes descends 

 the Maroni, the chief watercourse of French Guiana. According to Coudreau, 

 its highest summit is Mount Timotakem (2,624 feet), which lies in the western 

 section of the range. Few of the travellers that have visited this mountainous 

 region have laid down accurate itineraries of their routes, and hitherto (1894) 

 Coudreau is the only explorer who has mapped the main range with any approach 

 to accuracy. It is all the more difficult to determine its exact form and trend 

 that all the slopes, as well as the intermediate valleys, are clothed with a con- 

 tinuous mantle of dense woodlands. 



^one of the Tumuc-Humac crests are lofty enough to rise above the zone of 

 * Henri A. Coudreau, la France Equinoxiale, 



