Geology 



basalt of a later date, which ran nearly at right angles 

 to the older set and were unaffected by any metamorphic 

 changes. 



In one place was a clear section of the great thrust- 

 plane, and the gneisses could be seen beneath it, the 

 later basalt dykes being cut off by the thrust. Thus 

 clearly the forces which produced the metamorphism 

 were not the same as those which caused the thrust- 

 plane, the sequence of events having been 



(a) Formation of the igneous complex of granites, gabbros, and of 



the ancient sediments with dykes of dolerite or basalt. 

 (ft) Metamorphism of the above to form the gneisses and schists. 



(c) Intrusion of the later basalt dykes. 



(d) Production of the thrust-plane. 



The ancient crystalline rocks are often very rich in 

 minerals, and it therefore behoved us to keep a sharp 

 look-out for signs of anything of value. 



An examination of the river to the north of the 

 thrust-plane showed that it divided into three branches, 

 none of which was likely to prove navigable. They 

 were very rapid, and appeared to carry a large amount 

 of gravelly matter, which they were depositing in huge 

 spreads and terraces before entering the open valley up 

 which we had travelled. 



The fact that the rivers were no longer navigable 

 necessitated our travelling on foot as, of course, no 

 horses were available in these wilds, and indeed in many 

 parts the country was so rough that they could scarcely 

 have travelled. 



Accordingly a camp was established near the parting 

 of the streams and called Three Forks Camp, the canoes 



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