THE PHYSICAL HISTOEY OF THE FJORDS OF NE\V ZEALAND. 157 



interior depths (36 fiiis.) than are shown on the sand bar at 

 its mouth (it fins.). It would certainly appear that, weak 

 though the tidal currents of the outer sound may have 

 been, they were sufficient to carry sand and gravel and to 

 deposit it in the absolutely still water at the entrance to the 

 cove. Now had these phenomena resulted from the filling 

 of glacier excavated basins, similar basins, in the form of" 

 lakelets and tarns, would reasonably have been expected 

 above sea level, but so far as I know, such have not yet 

 been discovered. 



7. Form of entrance to the Soimds. — Another feature of the 

 fjord mouths, illustrative of the power and prevailing 

 direction of the winds and current, is apparent on inspection 

 of the chart. In nearly every case the north side of the 

 entrance has a tongue- like projection to the soutli or south- 

 west, Avhile the opposite southern side shows a concave 

 curve of erosion, as Avill be clear from the accompanying 

 sketch of the mouth of Bligli Sound. 



_ The only fjord of any size, the mouth of which has been 

 silted up, is Martin's Bay and its fjord continuation, Lake 

 McKerrow or Kakapo, and it is rather remarkable that this 

 is the only old valley which faced directly to the north-west 

 — or to the direction of the prevaihng wind. It was, more- 

 over, the first encountered by the coast drift in its southward 

 journey. It is clear that the sand drifted into the bay had 

 but little chance of escape against the prevailing wind, 

 and was piled up until it formed a bar tliree miles wide, 

 effectually ponding back the inner waters of the fjord, 



8. liocks lininfi the Sound. — The rocks in which the sounds 

 occur are eruptive granites and hard metamorjDhic gneisses, 

 both well calculated to withstand the onslaught of nature's 

 denuding agents for long ages. In Caswell 8ound, a bed 

 of marble, of poor quality, has been found. The restriction 

 of the sounds to the comparatively limited area mentioned 



