MOUNT KnKAIMA IN BK1T18H GUIANA. 3 



JlijHHtmnec and Structure of lioritihta, and its Geographical Relations to the Moun- 

 tain-systems of South America. — Im Tliuni and Perkius, who made the first ascent on 

 December 18, 18S I, reached (he top under unfavourable conditions: they had ascended 

 that dav from their base-camp at 5100 feet, and only reached the summit in the 

 afternoon, when clouds almost invariably envelop it; they had no means of remaining 

 there, and were forced to return after a very short stay of three hours. Perkins speaks 

 of these clouds as impenetrable (Proc. Boy. Geogr. Soe. vii. 1885, p. 532)*; at all 

 events they limited the range of exploration, and the report was made that "the 

 vegetation on the summit is extremely scanty and insignificant, there being no trees, 

 only small hushes from three to six feet in height, growing at long intervals." It has 

 been reserved for McConnell and Quelch to ascertain that there exist in favoured 

 places trees which attain a height of no less than forty feet. 



Of the ascents of Dressel and Kromer I can glean no more than is in a brief notice in 

 • Timehri,' 1887, p. 330. Neither can have remained on the summit for more than a fevi 

 hours. 



The features of this summit are: — Blackened elevated ridges, irregularly terraced and 

 rugged; winding gullies which drain away the superabundant rain through shallow 

 pools ; patches of sand in their shelter with isolated small bushes ; clumps of vegetation 

 lodged in the most protected s]>ots ; piles of wind-cut rocks without a sign of plant-life, 

 rising into pinnacles ; no soil ; the keen northerly wind, and mists which gather at least 

 after noon on almost every day in the whole year. The highest pinnacle rises to 

 8740 feet ; the deepest gully may be 400 feet helow it. 



The known sides of the mountain which face north-east and south-easL, produce rocky 

 sivannah up to 5000 or 5100 feet, the rocks so numerous that Ajipun likens the country 

 to a grave-yard ; then forest to 7100 feet, dense below but stunted and more open above ; 

 and from this altitude rise the precipitous cliffs, which give to the whole the appearance 

 of a vast fortress with a tree-clad glacis slope. 



These precipices were deemed impossible of ascent by the travellers they had baffled 

 until AVhitely indicated, and im Thurn showed practicable, the one known ledge leading 

 to the summit. 



The rock is a quartzose sandstone interbedded with diorite. The topmost and thickest 

 bed of diorite comes to the surface where the dense forest is ; the lower beds make a 

 series of terraces down the lower slopes. These beds lie perfectly horizontal without 

 folding or other sign of any great disturbance. Diorite lends itself to the formation of a 

 soil f, the sandstone does not. 



Such sandstones as constitute Roraitna have a very wide extension in South America ; 

 they pass eastward into Surinam; Duida is made of them; they form the bed-rock of 

 the llanos of Venezuela, and appear in the Caripe mountains to the east of Caraeas ; 

 in Brazil the area occupied by them is immense. 



* Of. im Thurn in ' Timehri,' 1 885, p. 41. 



t The Indians prepare their provision-grounds on the diorite (see Brown & Sawkins, Reports, p. 17). ami those 

 living under the south-eastern face of ltoraima have placed them far up- the sister-mountain of Kukenaam, \\ 

 the diorite comes to the surface (Quelch. in ' Timehri,' 1895, p. 16 I I 



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