Yol. 62.] GEOLOGY OF DT7NEDIN (NEW ZEALAND). 383 



The surface of the Peninsula is hilly, in places almost mountainous. 

 The highest elevations are : Mount Charles (Moehau) 1340 feet, 

 Sandy Mount 1068 feet, and Harbour Cone 1044 feet ; but several 

 other elevations rise above 1000 feet. These elevations are sepa- 

 rated by deep V-shaped valleys, with steep thalwegs that terminate 

 in sandy flats on the ocean-coast, or at the apices of the mud-flats 

 running into the harbour-bays. 



With the exception of one or two small outcrops, the Peninsula is 

 built up exclusively of volcanic rocks. 



The Otago Peninsula is not different in structure from that part 

 of the mainland which is adjacent to it, nor from the coast-line 

 extending 4 miles to the south and 10 miles to the north. Yarieties 

 of volcanic rock similar to those that form the Peninsula are 

 found over all this extent, and they reach 8 miles inland. The 

 whole of this district is a geological unit, the nature and structure 

 of which are described in the following pages. 



The description of the physiographical features of the Peninsula 

 just given applies almost exactly to the rest of this district, although 

 in both its northern and southern portions the various natural 

 sections displayed in sea-cliffs and stream-valleys reveal a Kainozoic 

 sandstone lying somewhat unconformably beneath the volcanic rocks. 

 At the extreme limits of the district, the sandstone is seen to repose 

 with a highly-un conform able junction upon the metamorphic rocks. 



The coast-line immediately to the south of the Peninsula and 

 to the north of Waitati, exhibits features rather different from 

 those shown elsewhere in the district, for the Kainozoic calcareous 

 sandstones are intersected by vertical joints ; consequently, perpen- 

 dicular cliffs without fringing beaches, but with outlying stacks, 

 are frequent. North of the Peninsula, the sandy flats filling the 

 smaller inlets are as characteristic as on the Peninsula itself. 

 Murdering Beach, Kaikai's Beach, and Long Beach have an 

 appearance closely similar to Sandfly Bay and Te Onepoto on 

 the Peninsula. The larger inlets, again, have been converted into 

 extensive tidal flats, with a sand-flat nearly closing the entrance. 

 This is typically shown in Blueskin and Purakanui Bays. 



The north-western shore of Otago Harbour has the same general 

 characters as those mentioned in the description of the south-eastern 

 side. The Port-Chalmers peninsula projects in a southerly direction, 

 almost opposite the Portobello peninsula, which has a north-westerly 

 trend. The width of the harbour is here still further contracted by 

 the presence of two small islands (Quarantine Islands) between the 

 two peninsulas. This chain of peninsulas and islands divides the 

 upper from the lower harbour. The north-eastern entrance of 

 the harbour is, as in the case of the other large inlets, partly 

 closed by a sand-flat; but the tidal flow of water, assisted by the 

 discharge of the numerous streams that flow into the harbour, is 

 sufficient to keep a moderately-deep channel clear, so that vessels 

 of large tonnage can enter and leave at suitable states of the tide. 



The surface of this district is even more rugged than that of the 



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