. The geology of the goldfields of British Guiana. ular, and show no signs of having travelled far from their places oforigin. The quartz pebbles in the gravels of the lower reaches, andthe flats of the creeks and streams, are also more or less angular and,as a rule, only slightly water worn. As the river is apprt»ached thepebbles become more water-worn. In the higher placers the gold in the gravels is coarse and in manyplaces nuggety, while in the lower ones it is usually in line grains,although fair-sized nuggets have been found in them. The largestnugget found in these districts weighed abo
. The geology of the goldfields of British Guiana. ular, and show no signs of having travelled far from their places oforigin. The quartz pebbles in the gravels of the lower reaches, andthe flats of the creeks and streams, are also more or less angular and,as a rule, only slightly water worn. As the river is apprt»ached thepebbles become more water-worn. In the higher placers the gold in the gravels is coarse and in manyplaces nuggety, while in the lower ones it is usually in line grains,although fair-sized nuggets have been found in them. The largestnugget found in these districts weighed about ten ounces. The placers in the higher parts of the Barima River, near theFive Stars and Jimbo Creeks have given high ^^ields of gold. Thecharacters of the placer deposits resemble those of the lower districts,but great boulders of epidiorite and of hornblende-schist occur in gold-bearing gravels on the average are about two and a half feetin thickness. The gold found in them is usually coarse and nuggety. [To face page 19S. Tlate P LAC E R WO R Kl N G. USING A TOM. Phofo hy H. I. PerHiif. The Placer Deposits. 199 and is very irregularly distributed through them. Very large nuggets,one of which weighed 333 ounces, have been found from time to timein this district. The placers in the Barama River Districts usually have from twoto as much as eight feet of yellowish to bluish clay over the the flatter and lower parts of the district, as near lanna and HoorieCreeks, in place of the clay, white quartz sand and whitish sandy claysand sericitic earths are found, their thickness being from three to fourfeet. The gravels consist, as a rule, of coarse, sub-angular white andbluish-white quartz pebbles, and along some of the creeks are accom-panied by boulders of hornblende-schist. The gravels vary in depthfrom one to four feet, whilst their yield of gold varies from two anda half to four pennyweights per cubic yard, the metal beingusually coarse. The Groete Cre
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