1 20 The Geology of the Gold Fields of British Guiana. 



but formerly called by the Bovianders " Come-and-see Hill." The 

 patli crosses this hill, and after passing near some placers situated on 

 the upper reaches of White Creek, ascends the Blue Mountain range, 

 passes over its flat top at about 700 feet above the sea-level, and leads 

 thence in a south-westerly direction over some of the lower spurs of 

 the hills to the Groete Creek landing which is situated about five miles 

 above the upper end of the Kamaria road on the Cuyuni River. The 

 only rocks exposed on this path are, in the part of it leading from the 

 Black Creek to the White Creek, chloritic and liornblendic schists 

 with concretionary ironstones and gravels. The higher hills consist 

 of hornblende-schist and of amphibolite varying in texture from fine to 

 moderately coarse. The sides and tops of the hills are covered with 

 ironstone-gravels, concretionary ironstones, and ferruginous sandstones 

 and conglomerates. On the Cuyuni side of the Blue Mountain, near 

 the foot of the hill, are exposures of well-foliated hornblende-schist and 

 of fine-grained amphibolite. These are metamorphosed rocks originally 

 of the gabbro-diabase type. 



7'he Cuyuni River. — At Kartabo Point, at the junction of the 

 Mazai'uni and Cuyuni Rivers, a broad expanse of rock is visible at 

 low tide ; while near the point are several exposures of rock on the 

 banks of the river, some of which have been worked as quarries. 

 The rocks consist principally of grey granite like that at the Penal 

 Settlement, but pegmatite or giant-granite is present in far greater 

 abundance. In places good specimens of graphic granite may be 

 obtained. Mica is present in the giant-granite, sometimes in large 

 plates, while here and there red garnets are fairly abundant in the 

 pegmatite-veins. A little to the westward of the road landing the 

 medium-textured light-grey granite is seen with a glistening darker- 

 coloured, fine-grained rock apparently intrusive in it. Both are traversed ' 

 by veins of coarse pegmatite, which in places contain garnets. 

 The fine-grained rock is seen, on microscopic exann'natiou, not 

 to be an intrusive igneous rock, but a clastic sedimentary rock caught 

 up in, and intensely metamorphosed by, the granite. 



For about a quarter of a mile west from the point the right bank 

 of the river shows here and there exposures of granite and of pegmatite, 

 the latter frequently in various stages of decomposition. The granite 

 is exposed at intervals for about two and a half miles up the Cuyuni 

 River. A little below Arian Island a ridge of rocks crosses the river, 

 and consists of square angular blocks of a very fine-grained light- 

 coloured aplite containing here and there small garnets. Between this 

 place and Batavia Island masses of the grey granite are exjDosed at 

 intervals. At the point below Little Batavia Island the gi-anite, 

 which is here coarse-grained and veined with quartz, contains caught- 

 up pieces of granitite-gneiss. The rocks below Batavia Island consist 

 of fine-grained granite, and are succeeded by a belt of coarse-grained, 

 while those at the lower end of Batavia Island are fine-grained. The 

 rocks exposed on the small islands near the lower landing of the 

 Kamaria Road are gneisses varying from hornblendic to feldspathic in 



