. The geology of the goldfields of British Guiana. PAKATUK FALLS (THIRD CATARACT), UVER rOKPHYKITIC GRANITITE, POTARO RIVER. Photo hy H. I. FerJci Tt, fare p„(je 101.] Plate AMATUK FALL, OVER SANDSTONE,POTARO RIVER. Flwtu Jy //. /. Perlins. The Polar0 and Kuribrong Rivers. 161 one strikes across the river from east to west. Between these dykes andabove them exposm-es of altered porphyrite occur, and at a distance ofabout a [[uarter of a mile from the creek a very fine-grained compact felsiteis exposed, which has a red-chocolate colour, and much resembles theso-called jasper commonly found
. The geology of the goldfields of British Guiana. PAKATUK FALLS (THIRD CATARACT), UVER rOKPHYKITIC GRANITITE, POTARO RIVER. Photo hy H. I. FerJci Tt, fare p„(je 101.] Plate AMATUK FALL, OVER SANDSTONE,POTARO RIVER. Flwtu Jy //. /. Perlins. The Polar0 and Kuribrong Rivers. 161 one strikes across the river from east to west. Between these dykes andabove them exposm-es of altered porphyrite occur, and at a distance ofabout a [[uarter of a mile from the creek a very fine-grained compact felsiteis exposed, which has a red-chocolate colour, and much resembles theso-called jasper commonly found in placer-gravels. This is probablya quartz-porphyry altered by contact with diabase. It is traversed bya dyke of diabase trending north and south across the river, which hashere a local direction of east and west. For a distance of about oneand a half miles, to near Oewang Creek, quartz-poxphyry and poiphyrite,more or less altered, occur. Near Oewang Creek a l)road belt ofepidiorite is traversed by the river, and the rocks in ifc are coveredwith ironstone-conglomerate. Opposite Oewang Creek, and for abouthalf a mile south of it, epidiorite is seen at intervals, the gene
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectgeology, booksubjectp
