East Valley Conclusion 



been designed and was on its way up the river from 

 Port Hutton. 



A light railway was also under construction from 

 Three Forks to the point where we had originally left 

 our launches at Base Camp, and a small town was 

 already growing up there. This would probably become 

 of some considerable importance, as it would be here 

 that the transhipment from barge to railway of all 

 goods intended for Three Forks would take place, and 

 consequently stores and warehouses would have to be 

 erected. 



In order to complete the preliminary survey of the 

 district round Three Forks we had still to explore East 

 Valley. It will be remembered that the sands at the 

 foot of that valley contained large quantities of the 

 mineral magnetite, from which we might conclude that 

 rocks of a basic character occurred higher up the stream. 



A careful examination of the sands showed that in 

 addition to quartz and magnetite they contained grains 

 of greenish chromite or chrome-iron ore. The presence 

 of this ore pointed to the occurrence of extremely basic 

 rocks, and about ten miles from the camp we came upon 

 exposures of rocks belonging to the ultra-basic division. 



In one of these, consisting for the most part of the 

 mineral olivine (Mg 2 SiO 4 ), there were masses of chromite 

 which appeared to have segregated out from the re- 

 mainder of the mass while cooling had been in progress. 



Chromite segregations in ultra-basic rocks, such as 

 that with which we were dealing, were known to us as 

 frequently containing some of the rarer metals, and we 

 consequently made a very careful examination of a large 

 quantity of the material. In two instances we found 



293 



