rh>^ Plact'r Deposit. 201 



the river. The overburden is a reddish-yellow to a deep red clay, 

 varying in depth from eight to ten feet. The gravels consist near the 

 water-side of water-worn quartz pebbles, and at a distance from it of 

 aiigular to sub-angular fragments of quartz, with nodules of con- 

 cretionary ironstone. In places pieces of quartz, carrying more or less 

 free gold, are found in the gravel. The gravels yield from two and a 

 half to three and a half pennyweights of gold per cubic yard. A 

 nugget weighing ninety ounces was found in this district. 



The only jjlacers of importance which have been worked on the 

 Mazaruni Paver are the very productive ones on the Isenaro Creek, 

 st)me miles below the Peiamah Falls. The valley-placers consist of 

 more or less angular fragments of quartz, fragments of partially 

 decomposed granite and greenstone, with abundance of concretionary 

 ironstone, and much ilmenite-sand. The overburden is either yellowish 

 or red clay, and vai'ies in depth from a few inches to three or four feet. 

 The hillsides are coveretl thickly with ii'onstone-nodules, lying on a 

 deep-red laterite. Both the valley gravels and the laterite 3aeld gold. 

 The average 3deld at Isenaro has been about three pennyweights of 

 gold per cubic yard of j^ay-dirt. 



The Esxpqiubo, Fotaro, and Konawaruk Placers. — The most 

 northerly placers which have been worked in this district are the 

 veiy productive ones at and near Omai. 



The valley-gravels at Omai consisted of angular fragments of 

 (juartz, more or less rounded pebbles of concretionary ironstone, with, 

 here and there, pieces and small boulders of diabase, epidiorite, 

 chlorite rock, and quartz-porphyry. The gravels varied a good deal in 

 thickness, being from one to about three feet. Near the heads of the 

 ^■alleys and ravines their overburden was not more than a few inches 

 in thickness, whilst in the lower, more open, parts it was from four to 

 six feet. 



The laterite and the ironstone gravels on the hillsides are more 

 or less auriferous ; their non-auriferous overburden varies from seven 

 to eleven feet. 



The gold in the valley-gravels varied from fine dust to small nuggets. 

 !Some large nuggets were also found, one of which weighed eighty-foui- 

 ounces. The average yield from the placer gravels was about two and 

 a half pennyweights per cuVjic yard. 



About one thousand small diamonds were found whilst the gravels 

 in Gilt Creek were being worked. 



Tlie Potaro Placer Gravels. — The placer gravels towards the head of 

 the Tiger Cx-eek District are usually somewhat shallow, their overburden 

 of brownish-yellow and red clay and loam being about two and a half 

 feet in depth, and generally consisting of a mixture of angular whit« 

 quartz with concretionary ironstone in large proportions. In some of 

 the placers the gravels consist wholly of white angular quartz. Not 

 unfrequently large blocks of diabase, of quartz-jiovphyry and of 

 concretionary ironstone are found in the placer gravels. The average 



P 



