428 Transactions. — Geology. 



Maau Hill, locally known as Tanna Hill, situated near the 

 University Mining School, has heen entirely overlooked. Here 

 we have a succession of rocks almost identical with that at 

 Waikouaiti North Head and at Kaikorai Valley. 



A few yards below Union Street Bridge, in the steep bank of 

 the Leith, is seen a bed of grey silts containing a few imperfect 

 leaf-impressions, numerous broken plant-remains, and a few 

 larger pieces of carbonised driftwood. The silts are not con- 

 tinuous for more than 25 yards, and, so far as they are 

 exposed, they thin out in both directions against a coarse 

 tuif-like sandstone. They exhibit characteristic current-bed- 

 ding. Overlying the plant bed there is a deposit of gravels 

 and sands composed principally of volcanic material. The 

 gravels in their turn are capped by the flow of rudely columnar 

 basalt which forms this well-known eminence. A deposit of 

 volcanic-ash rock rests on the undulating surface of the basalt. 

 In the bed of the stream, under the bridge, the plant silts are 

 seen resting on coarse volcanic breccia or agglomerate. 



The succession in this important and interesting section is 

 therefore as follows : — 



1. Surface clays and soil. 



2. Volcanic ash from 8 ft. to 15 ft. thick. 



3. Basalt-flow, about 25 ft. 



4. Gravels, about 18 ft. 



5. Grey plant silts, 5 ft. to 7 ft. thick, resting at ends 



agamst tuff-like sandstone of variable thickness. 



6. Coarse volcanic breccia. 



At Waikouaiti, Kaikorai, and Waitati the plant-bed series 

 rests directly on the Caversham sandstone, and at Te Manu 

 Hill on fragmentary volcanic ejecta. The lesson to be de- 

 rived from this is that Dunedin was situated within the 

 theatre of volcanic activity during the period of the earlier 

 ■outbursts. 



Te Manu Hill is a place of great geological value, and I 

 trust that the exigencies of the Univeisity will not require 

 its removal, but that it will be reserved for all time as a geo- 

 logical witness of the past history of Dunedin. Its destruction 

 would be an irreparable loss to geologic science, and cause 

 the obliteration of a geological record that could never be re- 

 placed.='= Apart also from its geologic and scenic value, Te 



• Mr. A. Hamilton informed me, after this paper was prepared, that 

 no interest had previously been attached to Te Manu Hill by geologists 

 because it was believed that the gravel and silt beds were of comparatively 

 recent date, and abutted against the basalt instead of underlying it. In 

 order to put this question beyond idl doubt I caused a pit to be sunk in 

 the floor of the old quarry facing the IMining School, and trenches to be 

 dug at the foot of ihe clil! on the l.eith Street side of the hill. In all 

 places the gravels were found below the basalt-fiow, as described above. 

 —J. P. 



