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mined and carried away, keeping an upright face of some 6 or 7 feet ; when 

 this face reached the groins, the caissons, one by one, as far as the river 

 current affected them, dropped about 5 feet, but once down kept their position, 

 effectually canting off the river current, and once up to the groins the upright 

 face disappeared and the beach took a sloped form with a fall of about one in 

 fifteen ; and I am of opinion that these groins prevented the river from cutting 

 into Revell-street and destroying many valuable buildings. The drawing 

 shows the spit after the river had broken through it, but I have shown in 

 dotted lines the shape of the spit before this took place. It will be seen on 

 looking at the rain diagram, that the year during which the sea encroachments 

 took place is remarkable as having the least rainfall, and consequently the 

 effect of the sea on the river current would be at its maximum. 



The islands shown off' the two spits, in drawing (ISTo. 2), were banks of 

 shingle, which were afterwards driven on to the spits, and materially 

 streng-thened them. Tn December, 1867, during a heavy flood, the river again 

 broke through the north spit, running straight out ; this was caused by a 

 wreck (the " Gratitude ") which was lying on the north spit, on the river side, 

 about five chains from where the river turned southwards ; the river first ran 

 over in a very small stream to the north of this wreck, but its position causing 

 it to act as a groin, the whole river was very soon turned across the spit to 

 the northwards of it. The wreck had afterwards to be removed by blasting, 

 as it was causing the river to do a great deal of damage to the north point. 



I noticed after this that at low water the river was 3 feet lower than 

 before, and the floods were not so high by about 2 feet. The surveys of 

 February and May, 1869, show the gradual settling down of the form of 

 river mouth under the new circumstances. 



THE RIVER AND HARBOUR. 



The river brings down a great quantity of shingle, and thus causes 

 continual changes in the position of the channel. The banks generally are 

 composed of vegetable mould and sand, deposited by the river at different 

 times ; one of these layers, below the water level, has a great deal of sand in 

 it, and on this the river acts very quickly, undermining the bank above, which 

 often falls in where unprotected by some yards at a time. 



There is no large stone near the town such as would answer for protective 

 works, and to fetch stone from the Kanieri would, in the earlier time of the 

 diggings, have been too expensive ; works of that kind were therefore neces- 

 sarily formed of destructible material. The first part of the wharf was formed 

 with piles, driven 10 feet into the solid, sheeted behind with hoi'izontal planking, 

 tie piles being diiven 20 feet back, and timber horizontal ties connecting them 

 with the face ; the space behind the front face was then filled in to the level of 

 the cajjping with brushwood at bottom, and then gravel. The filling with 



