160 Transactions. 



rocks have a dip approximating 1 in 8 (7°) in a direction varying between 

 20° and 55° south of east. In the north-eastern part volcanic rocks rest 

 on an eroded surface of the marine beds and form the caps of the ridges. 

 The upper part of Saddle Hill, which is just outside the western border, 

 is composed of basalt. Beds of clay represent the principal deposit formed 

 since the cessation of volcanic activity. 



PREVIOUS OBSERVERS. 



The earliest reference to the Green Island area may be quoted from 

 Hutton (1875, p. 13) : " In January, 1862, Dr. W. Lauder Lindsay delivered 

 a lecture in Dunedin on ' The Place and Power of Natural History in 

 Colonization,' in which he mentions the volcanic rocks of Dunedin, Saddle 

 Hill, &c. . . . He considered the sandstones of Green Island and 

 Caversham to be either Tertiary or Upper Cretaceous." 



Hector first reported on the field in his " Departmental Report of the 

 Geological Survey of Otago " of 1864, and subsequently in the Reports of 

 Geological Explorations during 1871-72. 



Hutton (Hutton and Ulricii, 1875, p. 47) gave a brief account of the 

 geology, in which he placed the sedimentary rocks and coal-measures of 

 Green Island in his Oamaru formation. In his " Geology of New Zealand " 

 (1885, p. 206) he refers to the belemnites from Green Island, but maintains 

 that other palaeontological evidence argues for a Tertiary age for the rock 

 in which it occurs. 



McKay (1877, pp. 59-60) searched unsuccessfully in the vicinity of the 

 Chain Hills and Abbott's Creek for fossils. At Green Island he obtained 

 a number of fossils from a shaft sunk on Mrs. Shand's property. The 

 Brighton calcareous beds were also visited, and a collection made therefrom. 



Marshall (1906) describes the volcanic rocks of the area, and mentions 

 the Brighton beds as being Tertiary in age. 



Park (1910b ,pp. 90, 120-35) includes the belemnite bed in his Waipara 

 series, of Cretaceous age He describes and gives sections of the marine 

 and terrestrial rock exposed between Saddle Hill and Dunedin, classing 

 them in his Oamaru series, the coal-measures corresponding to the lowest 

 beds at Oamaru 



Morgan (1916, p. 14) argues that the coals of Brighton and Green Island 

 are of the same age — i.e., Cretaceous — and that in some upper horizon an 

 unconformity exists. 



TOPOGRAPHY. 



The chief point of interest is the evidence of elevation and depression 

 of the land in post-Tertiary times. The Kaikorai Stream indicates depres- 

 sion of the land, for it has a wide flood-plain and is tidal several chains 

 up-stream from its junction with Abbott's Creek. From Abbott's Hill and 

 Kaikorai Hill the slopes to the middle of the valley are in places fairly 

 steep ; waterfalls and rapids are found in the upper parts of the creeks. 

 Kaikorai Stream and the creeks to the west of Stony Hill show a mature 

 form in their lower reaches. Abbott's Creek is at sea-level where it crosses 

 the Main South Road, Christie's Creek reaches the level of the sea on 

 crossing the old Brighton Road, and the Kaikorai is at sea-level 10 chains 

 above the junction with Abbott's Creek From the Main South Road to 

 the sea the flood -plain of the Kaikorai has an average width of about 

 60 chains. Plains composed principally of gravel stretch far up the creeks. 

 Obviously, the physiography points to a depression of the land. 



Terraces about a chain wide and 15 ft. above sea-level occur on the 

 right bank of the Kaikorai Stream, about one mile and a half from the 



