. The geology of the goldfields of British Guiana. ite contains smallcrystals of iron and copper pyrites. Near the second cataract fromthe foot, a narrow dyke of a porphyrite runs through the granitite,while a bxoad el van of quartz-porphyry traverses the granitite, whichis here very porphyritic, at the third cataract. Al)ove the cataractsis a series of small rapids, where in places the quartz-porphyryis traversed by veins of granite. A little more than two miles from the top of the cataracts theriver crosses a narrow d3^ke of epidiorite, trending from north-east to south-west; and in the neig
. The geology of the goldfields of British Guiana. ite contains smallcrystals of iron and copper pyrites. Near the second cataract fromthe foot, a narrow dyke of a porphyrite runs through the granitite,while a bxoad el van of quartz-porphyry traverses the granitite, whichis here very porphyritic, at the third cataract. Al)ove the cataractsis a series of small rapids, where in places the quartz-porphyryis traversed by veins of granite. A little more than two miles from the top of the cataracts theriver crosses a narrow d3^ke of epidiorite, trending from north-east to south-west; and in the neighlwurhood of Ekureparu Creek,about four miles south-west from the head of Pakatuk, the manyrocks which are exposed on the banks and in the river consist ofepidiorite. Near the mouth of the Ekureparu Creek the river flowsfor about three miles from the north-west, and about two hundredyards north of the mouth of the creek a dyke of dial)ase trends northeast and south-west, while about one hundred yards further another Tlate 20. [To face pnr/e 1(».. PAKATUK FALLS (THIRD CATARACT), UVER rOKPHYKITIC GRANITITE, POTARO RIVER. Photo hy H. I. FerJci Tt, fare p„(je 101.] Plate 21.
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectgeology, booksubjectp
