114 The Geology oj the Gold Fields oj British Guiana. 



former line of the Barima-Barama Road, is similiar in structure to that 

 of Arakaka, but the basic rocks are usually hornblende-schists. 



Little appears to be known regarding the geological structure of the 

 district between the Barima and Barama Rivers, with the exceptions of 

 the parts where the goldfields situated between Arakaka and Mazawini 

 landing are at present being worked. Judging from Sawkins and 

 Brown's report (page 36 of the "Geological Reports") on the district 

 traversed by them between Aranka, on the Barama and the Manarie 

 Creek which flows into the Barima River, the structure of the country 

 is similar to that of the Arakaka and Mazawini Goldfields. They noticed 

 that the "greenish chlorite-schist " occurred in many places and in 

 some localities is pierced by "grey trap dykes," while the soil dug up 

 by armadillos is "invariably of a fine red colour." Examinations of 

 the rocks collected by them show that their "greenish chlorite-schist" 

 is the more or less schistose-porphyrite characteristic of the district, 

 while their " grey trap " is diabase. As gold has been found and 

 worked in the placers on the Sarawara Creek and on the Marakaikuru 

 Creek, whilst we obtained colours of gold by washing the I'esidual clays 

 which form the hill at Koriabo, this line of country is probabl}' similar 

 to the Arakaka-Mazawini district in being more or less auriferous. 



Near the Woorie Creek gold-workings are being carried on success- 

 fully in a district of sericite-schist. 



A few small diamonds have been found in the southern part of the 

 district near lanna. 



