362 Transactions. 



slopes of the Port Hills a few trees formed, a straggling connection with the 

 Riccarton Bush. In addition to this standing timber, fallen logs, mostly 

 of totara (Podocarpus totara), lay commonly among the tussocks till they 

 were gradually destroyed by grass-fires, thus indicating a former wider 

 extension of these forests. In the swampy areas round Lake Ellesmere and 

 on the low-lying eastern fringe of the plain there existed a great amount 

 of timber, chiefly white pine, or kahikatea (Podocarpus dacrydiodes), and 

 manuka (Leptospermum scopa/rium), some of which lay prone in the bogs, 

 while some formed the stumps of trees in position. Since kahikatea is a 

 timber which soon perishes on exposure to the weather, it is evident that 

 the destruction of these forests occurred somewhat recently. This was 

 attributed by the early settlers to the action of fire, but it is difficult to 

 understand how a water-logged swamp could have been thoroughly burnt 

 out, and it is extremely probable that this part of the forest of the plains 

 disappeared largely owing to the killing of the trees by water-logging due 

 either to depression of the land or to the flooding of land owing to the 

 changing course of rivers, itself perhaps partly due to depression, of which 

 there is entirely independent evidence. This is supported by the statement 

 of Mr. Dudley Dobson, Christchurch City Engineer, in connection with the 

 sinking of the sump for the Christchurch water-supply pumping-station at 

 the foot of the Cashmere Hills. While making this excavation he came across, 

 at a depth of 25 ft. beneath the surface, a fine specimen of a totara log, 5 ft. 

 in diameter. In close proximity to this was the stump of the tree with its 

 roots in proper position, extending 16 ft. across, and penetrating a layer of 

 clay, evidently the old land surface on which the trees grew. The level of 

 the roots was almost exactly that of high-tide mark, thus affording a clear 

 indication of the depression of the land. My attention has been drawn by 

 Mr. W. Wilson, of Auckland University College, to stumps in a similar 

 position near Pareora, south of Timaru, thus undoubtedly confirming the 

 existence of a downward movement of the land in the area immediately 

 south of the plains. Also, during heavy storms, pieces of submerged trees 

 are frequently washed out of the beds on shore just north of Timaru ; but 

 whether these are from drift material or from trees which are in position 

 it is impossible to say. This evidence of depression is supported as far 

 as this locality is concerned by the form of the shallow valleys cut in the 

 dolerite capping of the Timaru Downs, with their lower reaches occupied 

 by lagoons of brackish water ponded behind shingle bars, which were built 

 up by the pronounced northerly drift of shore material along the coast. 

 The drowned valleys of Banks Peninsula are evidence that a similar down- 

 ward movement of the land went on farther north. 



The instance cited on the authority of Mr. Dudley Dobson selves to 

 emphasize the existence of buried forests of large trees on the former sur- 

 face of the plains. The occurrence of timber, either drift or in position, 

 at great depth beneath the surface is widespread in this area. Not only 

 is it found in the artesian bores at all depths up to 450 ft., but it is met 

 with in making excavations for foundations in Christchurch itself, and also 

 in the gravel-pits opened on the plains both within and just without the 

 artesian area. In a pit at Hornby, about six miles west of Christchurch 

 and 90 ft. above sea-level, numerous pieces of the stems and roots of trees 

 are found 40 ft. beneath the surface — that is, to the depth of the excava- 

 tion. These are evidently of drift material, but they show that the totara- 

 trees from which they were derived flourished at higher levels on the plains 

 when the bottom of the pit formed the surface of the ground. Throughout 



