BY D. MAWSON. 449 



the north of Wuss, raised coral limestone encrustations appeared 

 along the shores at elevations of 12 ft. only. 



vi. Recent Fres h-w ater D eposit s.— On the banks 

 of the Atsone River, about two miles from the mouth, beds out- 

 crop quite 30 ft. in thickness composed of fresh-water drift 

 materialj mostly matted leaf-remains with fairly numerous fresh- 

 water .shells. Their deposit was formed prior to the latest 

 upheaval, which gave the river a chance to cut a channel through 

 its earlier sediments. Similar deposits are developed in greater 

 or less extent near the mouths of all the more important streams. 

 Along the valley of the Navaka for a considerable distance from 

 its mouth are great flood-deposits a quarter of a mile in width, 

 of volcanic boulders and pebbles brought down from the high 

 mountains to the north. 



Another deposit relatively unimportant is that of travertine 

 encrusting the beds of creeks which traverse limestone regions. 

 Leaves of trees, sticks and other matter happening to fall into 

 such streams are after a time, as they rot away, reproduced as 

 negative casts in travertine.* 



vii. Evidence of Faulting in S a n t o. — Along the 

 west coast considerable faulting has taken place, resulting in 

 much complication of the geology. 



The general features of the district south of Wuss suggest 

 peripheral faulting around Losobunu, developed most strongly in 

 a N.N. W. direction; crossing this series there appears to be radial 

 faulting, allowing the rivers a ready passage to the sea. An 

 example of this type is seen at Sauri'i, evidenced by the discord- 

 ance of the rocks on either side of the narrow^ river valley. A 

 further example is very noticeable crossing the agglomerates on 

 the cliffs a little north of Pareo. As indicated by the direction 

 of trend of the ridges on the eastern side of Losubunu, peripheral 

 faulting, no doubt, extends in that direction also. 



Dr. Guppy noted the same thing occurring in Solomon Island streams. 

 29 



