342 Transactions. — Geology. 



Some years ago I endeavoured to point out that Port Nicholson had 

 formerly been a fresh-water lake. Does not the occurrence of these pebbles 

 support that theory, supply direct evidence of lacustrine deposit which I 

 previously admitted we had not found, and show that the boundaries of the 

 lake were far outside those of the present b arbour ? 



I have reason to suppose that there are deposits of gravel high up on 

 the hills surrounding Port Nicholson. These may show the margin of the 

 ancient lake, while the sparsely deposited pebbles may show where these 

 were gradually distributed by waves or currents over the lake bottom. 



The theory involves great movements in the land, and a great sinking 

 in the direction of the Straits, but I do not see any other way out of the 

 difficulty. 



To obtain further proof of lacustrine deposit may be difficult, and will at 

 all events take much time. Should these deposits occur in the harbour 

 they must be overlaid by those of marine origin, and could only be found by 

 buring, but there are strata at Karori and Johnsonville, etc., lying on the 

 old rocks, which it might be well to study to see whether they are lacustrine 

 or marine. The talus on which that part of Wellington called Thorndon is 

 built might also yield some information, as also the lower parts of Te Aro. 



Art. XLV. — On Changes in the Hataitai Valley. 

 By James Coutts Crawford. 

 [Read before the Wellington Philosophical Society, 9th July, 1884.] 

 As I am rapidly bringing the Hataitai Valley into cultivation, and thereby 

 destroying geological landmarks, it may be as well to put on record what 

 will soon be lost to the eye. At present I refer particularly to the old 

 forest which at one time filled the valley, and whose stumps and logs are 

 apt to smash my ploughs. Doubtless the hills also were at one time 

 covered by forest, but all traces of this seem to have long ago disappeared. 



There are a series of sea-formed lakes, detached rocks, etc., showing a 

 depression of the land to the extent of about fifteen feet. This is the point 

 at which I propose to commence, as it would be desirable to fix some ap- 

 proximate date for this occurrence. 



The highest level of the land in the Hataitai Valley being now about 

 14 feet, it is evident that a depression of 15 feet would entirely submerge it. 

 We therefore find the valley to be filled with strata of sand and gravel, the 

 latter generally underneath, but also occurring in bars at various points ; 



* Geology of Otago, by Hutton and Ulrich. Dunedin, 1875, p. 40. 



