110 TJiA Gi'olo()y of f lie Gold Fields of Jiritish Guiana. 



The, Barama /i^ii'.?r.— -North-east of Aiiaturi, to its junction with 

 the Waini, the course of the Barama Kiver is through low swampy 

 alluvial land covered with dense forest, but having in places low forest- 

 clad hills, generally of red or ochreous gravelly clay, doubtless the 

 degradation-product of either epidiorite or of diabase. Examples of 

 such hills are those known as Captain Thompson's Hill and as KoV)i's 

 Hill. On the former hill are several blocks of white (juartz, and on 

 the lower ground to the south of the hill some enormous masses of 

 quartz are exposed in the forest. The quartz is glassy, with a bluish 

 tinge, and yielded no trace of gold upon assaying. 



Below Anaturi schistose rocks which are much decomposed are 

 exposed when the water in the river is very low. Between Anaturi 

 and Woori Creek quartz is exposed in several places along the course 

 of the river, the largest mass occurring a few miles above Anaturi, 

 where it is exposed not only in the bed of the river but in great masses 

 on the slopes of a low, forest-covered hill. The quartz is a quartz-schist, 

 probably a modification of an originally felsitic rock. 



Above the Woori Creek, and at intervals for about ten or twelve 

 miles along the course of the river, much-altered rocks occur which are 

 schistose in structure, light green in colour, and in places contain either 

 crystals or rusty casts of iron pyrite disseminated through them. The 

 rocks are highly metamorphosed and weathered porphyrite. The rocks 

 seen to the north of Caman's Short Cut near Torobaru Creek are, 

 as a rule, more schistose in character than those to the south of it. 

 In places near here the rocks are altered to sericite-schist. 



From near the Agawaris Creek to -near Urinambu the river bends 

 round the base of the Urinambu Hills. The rocks exposed in this 

 stretch of river consist of epidiorite, and probably the high country in 

 the neighbourhood is the same. 



From the western exposure of epidiorite to near Wynamu Creek 

 the rocks consist of more or less metamorphosed porphyrites, traversed 

 in places by dykes of epidiorite. 



From Wynamu to somewhat west of Cariacoo, near Kaikushie, 

 the river traverses, for a distance of about six miles, a district of 

 grey hornblende-granitite. Above this belt of granitite, as far as 

 Monossi, the country is one of more or less foliated porphyrite 

 and of schists derived from it. In places, as near Goring's Landing, 

 low hills of red laterite indicate where bands of more basic rocks 

 occur. 



A narrow belt of grey granitite crosses the river near Monossi 

 Creek. From this to a little beyond Mazawini Landing schistose 

 porphyrites again occur, The strike of the foliation of the schists 

 from Mazawini to Kaikushie varies from the north-east and south-west 

 to east and west, while the general strike below Agawaris Creek is 

 north north-west and south south-east. In many places the schists are 

 traversed by veins and reefs of quartz-rock and of quartz-schist, which, 

 as a rule, are not auriferous. Mazawini Landing is situated on a hill of 

 red laterite. This is probably the decomposition-product of an epidiorite. 

 The quartz-gravel in the laterite is auriferous. 



