256 Transactions. 



depth was one fathom under the bow of a small steamer of eighty tons, and 

 thirteen under her stern. There are no strong currents or tides in the remote 

 recesses of the Sounds to sweep away detritus far from the river-mouth, 

 so the angle of repose is extremely steep. Very fine particles must be carried 

 some distance, as dredgings show that the floors of the Sounds are almost 

 invariably composed of mud. In some cases, such as at the head of Milford, 

 shoaling is very rapid over the area of deposition : at one place, where 

 twenty years ago a depth of fourteen fathoms was recorded, mud-flats 

 covered with driftwood, and exposed at half-tide, now exist. Apart from 

 these, the beaches in process of formation are of extremely limited extent, 

 and if subjected to subaerial erosion would last but a short space of time. 

 Their absence at higher levels, noted by Hector, is therefore no proof that 

 the land did not suffer a depression with subsequent elevation. Captain 

 Hutton noted marine-cut terraces in certain places, particularly at the 

 entrance to Doubtful Sound on Secretary Island, and they are very well 

 marked near Puysegur Point, in the south-west of the area, so that it is 

 probable that a submergence took place, probably posterior to the glacia- 

 tion ; but the question does not seem to be connected in any way with the 

 cause of that glaciation. 



The main landscape-forms of this area, as has already been pointed 

 out by Andrews (1, 2), are produced by the modifpng effect of glaciation 

 on a well-developed stream-valley system. His conclusions can in general 

 be heartily indorsed. There are, however, one or two features which may 

 be further noticed. The first of these is the general orientation of the main 

 valleys. Although small valleys can be found running in all directions, 

 the general disposition of the main valleys seems to depend on some general 

 underlying cause. An examination of the map shows that the main arms 

 of the Sounds, and the lakes on the eastern border of the region, usually 

 lie parallel to two main directions, one running north-west and the other 

 south-west, thus cutting one another at right angles. This arrangement is 

 difficult to explain in the light of our present knowledge, but it is possible 

 that the formation of the valleys was dependent in the first case on lines 

 of crust-fracture, that the arms grew along these lines, and, in spite of 

 valley-forms being modified, the main directions were always preserved. 

 The smaller valleys running in irregular directions would be subsequent, 

 and determined largely, if not altogether, by the way in which streams 

 eroded the surface. It has been pointed out by J. W. Gregory that fiords 

 are found on the margins of fractured earth-blocks, and it is extremely 

 likely that this is the case here, although there is no positive evidence of 

 their presence. There seems, however, to be considerable difficulty in ex- 

 plaining the origin of the submarine valley of Wet Jacket Arm, and the 

 narrow Acheron Passage, running for miles behind Resolution Island, and 

 almost exactly at right angles to the Arm. The passage is deep throughout 

 its whole length according to the somidings on present charts, and there is 

 little rounding of the corners where it joins with Wet Jacket Arm. The 

 soundings do not reveal that it has been formed by the degradation of 

 a divide by ice erosion. It can be most easily explained as being the result 

 of a cross-fracture. Similar valleys on a less pronounced scale are found 

 connecting Daggs Sound with Doubtful Sound, though it is possible that 

 these may result from the destruction of a ridge by stream and glacier 

 action. 



It seems fairly certain that on the east side of the area an enormous 

 fault with a downthrow to the east or an upthrow to the west follows the line 



