. The geology of the goldfields of British Guiana. ble atshort intervals. Near Willis s Landing, at the northern end of thecurve, masses of very coarse hornblende-granitite occur, followedat about one hundred and fifty yards down the river by a narrowbelt of hornblende-schist trending east and west. The hornblende-schist is auriferous, and yields gold at the rate of two pennyweightsper ton of the rock. The placers near here are worked in fluviatilesands and gravels deposited at some former period by the river. Forhalf a mile north-east of Williss Landing the rocks in the river arehidden by san
. The geology of the goldfields of British Guiana. ble atshort intervals. Near Willis s Landing, at the northern end of thecurve, masses of very coarse hornblende-granitite occur, followedat about one hundred and fifty yards down the river by a narrowbelt of hornblende-schist trending east and west. The hornblende-schist is auriferous, and yields gold at the rate of two pennyweightsper ton of the rock. The placers near here are worked in fluviatilesands and gravels deposited at some former period by the river. Forhalf a mile north-east of Williss Landing the rocks in the river arehidden by sand-banks, while for a similar distance to Stout Fall,exposuies of coarse granitite occur at intervals. At Stout Fall the rapids are over coarse granitite with narrowveins of fine-grained, dark-coloured quartz-porphyry. From herethe river pursues a winding course to the north-east, the rocksseen being coarse gneiss and gneissose-granitite. These are crossedby elvans of fine-grained quartz-porphyry, which cause rapids in Tn fare pngo 171.] Plate TEMPLE BAR FALL OVER GRANITITE (iX RAINY season), KONAWARUK RIVER. Photo by H. I. Perkins. The Konatvaruk River. 171 the river about half a mile south-west of Long Falls. The seriesof cataracts and rapids, known as Long Falls, extend for abouta quarter of a mile, and along them coarse gneiss or gneissose-granitite is constantly exposed, a vein about twelve to fifteen inchesacross of black, fine-grained quartz-porphyry cutting through thegneiss at the head of the falls. The river follows a very windingcourse through coarse gneiss and gneissose-granitite, the bands of thelatter here and there giving rise to rapids. Tacuba Falls, another longseries of small cataracts and rapids, which extend for about fourhundred yards, are over coarse gneissose-granitite at the head, and overgrey gneiss of medium texture at the foot and lower parts. Below Tacuba Falls the course of the river is, compared to the upperreaches, free from sand-banks and fal
Size: 1774px × 1409px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, booksubjectgeology, booksubjectp
